Letters

Elizabeth A Hender,* Jeremy Raftos† * Scientific Officer, Hazardous Substances Section, Department of Human Services, PO Box 6, Rundle Mall, Adelaide, SA 5000; † Director, Paediatric Emergency Department, Women’s and Children’s Hospital, Adelaide, SA. Elizabeth. HenderATdhs.sa.gov.au To the Editor: We read with interest the study of Kisely et al,1 which showed a decrease in admissions for poisoning with paracetamol, but no coincident increase in use of other agents, as a result of the paracetamol recalls. We had noticed there was an unusually high number of presentations (18) to the Paediatric Emergency Department at the Women’s and Children’s Hospital, Adelaide (WCH), for poisoning with aspirin in 2000, compared with one presentation in 2001 and one in 2002. We wondered if the presentations in 2000 were temporally associated with the paracetamol recalls. We extracted all WCH presentations with a primary diagnosis of paracetamol poisoning (ICD-9 code 965.4), aspirin poisoning (965.1), nonsteroidal anti-inflammatory drugs (965.6) and poisoning with all other drugs (960–979.9) for the two recall periods (16 March 2000 to 21 May 2000; 6 June 2000 to 23 August 2000)2 and the same periods in 2001 and 2002. It could not be determined whether an over-the-counter preparation of a nonsteroidal anti-inflammatory drug had been taken. The results are shown in the Box. Presentations (P) and admissions (A) for poisoning with paracetamol, aspirin, NSAIDs and other drugs at the Women’s and Children’s Hospital, Adelaide 2000 restricted 2001 available 2002 available P A P A P A Aspirin 15 13 1 0 0 0 Paracetamol 23 6 34 13 34 14 NSAID 3 1 0 0 1 0 Other drugs 86 43 89 35 60 23 NSAID = non-steroidal anti-inflammatory drug. These data show that the number of paracetamol poisoning presentations and admissions was lower during the recalls than in the same period in subsequent years, but there was a higher number of presentations and admissions for poisoning with aspirin. All the aspirin poisoning presentations and admissions during the period when paracetamol was recalled were during the second recall (affecting SmithKline Beecham products). The other three aspirin poisoning presentations in 2000 occurred within 10 days of the end of the second recall. All but one of the 18 patients with aspirin poisoning who presented during 2000 were adolescents (17 females). Most of these exposures were likely to be due to intentional self-poisoning. Although it is not possible to reach any definite conclusion from these observations, we share the concerns of Balit et al2 that limiting the availability of paracetamol could result in an increase in poisonings with potentially more acutely dangerous agents such as aspirin, particularly for adolescents. There needs to be further consideration of the motivation of patients in choosing paracetamol and the source of the drug when taken for intentional self-poisoning before measures are taken to restrict access to paracetamol.

Elizabeth A Hender · Jeremy Raftos

Stephen R Kisely,* David Lawrence,† Neil J Preston‡ * Professor of Health Outcomes, Department of Psychiatry, Dalhousie University, Canada; † Post-doctoral Fellow, Institute for Child Health Research, Perth, WA; ‡ Research Psychologist, Fremantle Hospital and Health Service, Fremantle, WA. stephen.kiselyATcdha.nshealth.ca In reply: Balit et al raise the problem of distinguishing between intentional and unintentional ingestions. As stated in our article, we did look at deliberate and accidental poisonings separately, but space restrictions, not limitations of our dataset, prevented us from presenting the results.1 Of 2266 paracetamol poisonings, 1731 (76%) were coded as deliberate, 433 (19%) were accidental and in 103 (4.5%) the intention could not be determined. Restricting the analysis to the deliberate cases yields almost identical results. Our dataset may have contained poisonings with liquid or combination formulations of paracetamol that were not recalled. This factor would have operated before, during and after the recall and would only serve to reduce the magnitude of any effect, rather than accentuating it. We considered 2663 admissions for over-the-counter analgesic poisoning,1 as opposed to 143 in the NSW study.2 We did not look at telephone calls, as reliance on data from calls to a poisons information centre raises far more concerns about data quality than hospital statistics do. How reliable was the informant? How serious was the poisoning? Do telephone data contain less serious cases that do not require admission? Hender et al report the findings of an observational study restricted to a single paediatric emergency department attached to the Women’s and Children’s Hospital, Adelaide. Unfortunately, data for only three years are presented, with no information for the years before the recall. Neither do we know how many were intentional or unintentional. By definition, their data exclude adults. As they state themselves, it is not possible to reach any definite conclusions from their observations. We should not prematurely dismiss the possible benefits of restrictions on the availability of paracetamol. If there are concerns that restricting the availability of paracetamol might increase the use of other over-the-counter analgesics in poisonings, we should be investigating the effectiveness of restrictions on the availability of these as well. Who precisely benefits from continued sales of over-the-counter analgesics in catering pack sizes?

Stephen R Kisely · David Lawrence · Neil J Preston

Barbara M Miflin,* Kevin L Forbes† * Lecturer in Teaching and Learning Development, † Deputy Head, Years 3 and 4 MB BS Program, School of Medicine, University of Queensland, Herston Road, Herston, QLD 4006. barbara.miflinATuq.edu.au To the Editor: All established disciplines that have contributed to medical curricula in the past should play, as Weedon1 argued recently for pathology, a pivotal role in contemporary medical curricula. Indeed, students should be able to acquire better knowledge of a discipline through a problem-based learning (PBL) approach than through traditional teaching methods. The crux of the PBL approach is that knowledge, skills and the other professional attributes are learnt in a way that puts them into context and thus makes them meaningful and better remembered by medical students. The trouble is, as Weedon pointed out, the number of academics in the discipline of pathology is dwindling. The scarcity of academic pathologists, combined with the increased workloads of private pathologists, means that their input into designing and developing curricula and into pathology teaching may be increasingly inadequate. Pathology is not the only discipline to be underserved in today’s medical schools. In response to concerns about the medical curriculum, the Royal College of Pathologists of Australasia and other Colleges and interest groups have developed core syllabuses for use in medical programs. These developments are most welcome in view of the diminishing resources available for teaching in universities. In a PBL-oriented curriculum, teaching staff work in a multidisciplinary team in which the aspirations and limitations of each group are acknowledged, respected and acted upon in the context of realistic expectations of what is possible and what is necessary for medical graduates in the 21st century. Currently, in Queensland, a series of pathology modules for students to use during their clinical rotations would be well received. The use and interpretation of pathology tests are already built into PBL case studies, and could be extended into a module set as prerequisite learning for an attachment to a public or private pathology laboratory. Pathologists may also be able to use the syllabus to guide their teaching in mentorships for the elective components of medical programs. The needs of disciplines such as pathology will be best achieved through genuine understanding of the aims of medical schools to ensure appropriate, realistically achievable learning for students. When students are motivated to acquire knowledge of a discipline because they can see its relevance to solving patients’ problems, their enthusiasm for the discipline will be enhanced and they will learn well.

Barbara M Miflin · Kevin L Forbes

Donald D Beard Surgeon, 134 Beulah Road, Norwood, SA 5067. To the Editor: The issues raised in the editorial by Weedon1 are a sad reflection on current medical education. Weedon voiced the serious concern of the Royal College of Pathologists of Australasia regarding the downgrading and marginalising of the teaching of pathology because of the ascendancy of problem-based learning, to the detriment of the basic sciences pathology, physiology and anatomy. Weedon reminded us of Virchow’s pronouncement that applying the doctrines of pathology “helps to deepen biological knowledge, and to light up still further that region of the unknown which still envelops the intimate structure of living matter”. That statement also applies to anatomy and physiology. It could not have been said better. Some years ago, while I was on the Curriculum Committee of the University of Adelaide, the Committee agreed to recommend that the basic sciences continue to be taught throughout the medical course. Unfortunately, the recommendation was not accepted, and now the position is even worse. I find it very difficult to understand the priorities of the current medical curricula and who is making the recommendations. I feel the excitement of the study of medicine is disappearing, and hope it is not too late to reverse the current trend.

Donald D Beard

H Reginald Magee Vascular Surgeon (retired), “Alexandra”, 201 Wickham Terrace, Brisbane, QLD 4000. reginaldmATbigpond.com To the Editor: I was most interested in Weedon’s editorial on the teaching of pathology in the present medical curriculum.1 I have lamented the demise of anatomy teaching in undergraduate courses and regret that pathology is going the same way. In my view, anatomy, physiology and pathology are fundamental to understanding the disease process. They enable physical symptoms and signs to be interpreted in a logical manner so that a provisional diagnosis can be made. Once this has been done, it is reasonable to progress to ancillary aids to confirm or refute the original diagnosis. When doing operative surgery I used to ask my assistants questions, usually on anatomical features that were being exposed. Many, including some who possessed the primary surgical fellowship, could not identify simple structures such as the sartorius muscle when the popliteal artery was being exposed. Questions on structures in the neck were even less well answered. The present medical curriculum is directed towards problem-solving methods and the patient’s condition in relation to the environment and other conditions. But how much thought goes into the mechanism of disease and understanding physical findings? I consider medicine and surgery to be applied pathology, and therefore knowledge of the basic facts is essential. Future doctors may be proficient in the general and social aspects of medicine, but it would seem that their knowledge of the basic facts of anatomy, physiology and pathology and their understanding of the mechanism of disease may be no better than that of a “medicine man”.

H Reginald Magee

Colleen T Bruce,* Margaret M Sanger,† Paul S Thomas,‡ Jonathon R Petkus,§ Deborah H Yates¶ * Research Assistant, ‡ Senior Lecturer, Faculty of Medicine, University of New South Wales, Randwick, NSW; † Deputy Medical Director, Concord Repatriation General Hospital, Concord, NSW; § Medical Student, ¶ Senior Lecturer, Faculty of Medicine, University of Sydney. Correspondence: Dr Deborah H Yates, Department of Respiratory Medicine, St Vincent’s Hospital, Darlinghurst, NSW 2010. deborahy88AThotmail.com To the Editor: The demands of practising medicine can have significant effects on general health, work satisfaction, professional and non-professional life.1 We conducted a survey among senior medical staff in a metropolitan teaching hospital. The survey explored the pressures of work, social and family demands on consultants, and whether there was a difference between sexes. Participants completed a self-reported questionnaire on quality of life, levels of stress and feelings of work satisfaction, using previously validated questions and scoring from the General Health Questionnaire (GHQ-28, a 28-question subset of the GHQ)2 and Specialist Doctors Stress Inventory (SDSI).3 (Questionnaire available from authors on request.) Respondents answered anonymously and gave informed consent. Fifty-seven per cent of consultants (54/94) returned surveys, of whom a third (18/54) were women. The response rates were comparable to those of other physician surveys.4 On average, consultants had been employed at the hospital for 10.8 (SD, 8.0) years, had been qualified for 22.2 (SD, 9.6) years, and were working 47.7 (SD, 14.0) hours per week. Eighty-one per cent (44/54) were married, 74% (40/54) had children and 54% (29/54) lived in a double-income household. Half (27/54) reported an unreasonable ratio between work hours and leisure time, and 50% (27/54) reported feeling stressed. Despite this, 65% (35/54) believed they had or would achieve their ideal medical career. Female consultants worked fewer professional hours, but more hours in unpaid domestic work, than male consultants. Furthermore, female doctors were more likely to have had their career modified by family or social factors; more likely to use paid support to cope with their domestic workload; and, if they had children, more likely than men to have modified their careers to look after dependants (see Box). Consultants who reported feeling stressed were more likely than other consultants to report an unreasonable ratio between work hours and leisure time (74.1% [20/27] v 48.1% [13/27]; P = 0.05). Forty-one per cent (22/54) scored above 4 on the GHQ-28, indicating that a high level of stress and psychiatric “caseness” (ie, clinically significant levels of psychiatric disturbance) is experienced by senior doctors. This result is similar to that of a UK study in which 46% (30/65) of senior doctors reported experiencing high levels of stress.5 From our data there appears to be a significant relationship between stress, psychiatric “caseness” and hours worked (P < 0.001). Our study and others have identified potential reasons why women work fewer hours in medical work and have a shorter working life. These include having and caring for children, stress, dual-career marriages, personality and social expectations.6 Our survey highlights the fact that female consultants in Australia face undue pressure in balancing their medical and domestic roles compared with male consultants. There is a continuing need for flexibility in workplace and training environments for women in medicine to ensure equal career choice, balance between work and domestic commitments, and professional satisfaction. Comparison of self-reported factors between female and male consultants (n = 54) Female consultants (n = 18) Male consultants (n = 36) P value Mean age in years (SD) 45.3 (10.5) 47.7 (8.1) 0.43 Mean hours in medical work per week (95% CI) 33.4 (28.5–38.4) 54.7 (51.5–58.0) < 0.001* Mean hours in unpaid domestic work per week (95% CI) 22.9 (8.0–37.8) 10.6 (7.6–13.5) 0.02* Uses paid domestic support 14/18 (78%) 18/36 (50%) 0.05* Has children 11/18 (61%) 29/36 (81%) 0.12 Expects to achieve future medical goals 12/18 (67%) 24/36 (67%) 0.78 Has had career expectations modified by: Workplace 8/18 (44%) 22/36 (61%) 0.25 College/training 4/18 (22%) 7/36 (19%) 0.81 Family/social factors 12/18 (67%) 14/36 (39%) 0.05* Illness 1/18 (6%) 4/36 (11%) 0.51 Has had career opportunities modified by care for dependants 9/11 (82%) 10/29 (34%) 0.02* Reports partner is inconvenienced by respondent’s career goals 10/18 (56%) 9/36 (25%) 0.03* Mean score on GHQ-28 (95% CI)† 2.24 (1.81–2.68) 2.10 (1.95–2.26) 0.45 Psychiatric “caseness”‡ 8/18 (44%) 14/36 (39%) 0.30 Median job satisfaction score§ 3 (range, 3–4) 3 (range, 1–4) 0.15 Median life stress score§ 2 (range, 1–2) 1 (range, 1–3) 0.13 GHQ-28 = 28-item General Health Questionnaire. * Difference between men and women significant. † Minimum score = 0; maximum score = 28. ‡ ie, Clinically significant psychiatric disturbance (GHQ-28 score > 4). § Minimum score = 1; maximum score = 4. Data were analysed by Pearson’s χ2 test, Student’s t-test or the Mann–Whitney test and stratified by sex.

Colleen T Bruce · Margaret M Sanger · Paul S Thomas · Jonathon R Petkus · Deborah H Yates

Patricia A Figgis,* Allan R Glanville,† John L Harkness‡ * Thoracic Registrar (currently, Senior Registrar, General Intensive Care, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW, 2050); † Head of Thoracic Medicine, ‡ Director of Microbiology, St Vincent's Hospital, Darlinghurst, NSW. patriciafiggisAThotmail.com To the Editor: A previously well 57-year-old man presented to the emergency department with a 3-day history of severe dyspnoea. Six weeks earlier he had noticed coryzal symptoms with subsequent lethargy, reduced appetite with weight loss, and a non-productive cough. He then developed ankle swelling and increasing abdominal girth. He had a background of excessive alcohol consumption, but had abstained for 10 years. On examination, he was febrile and in respiratory distress, with a respiratory rate of 35 per minute, pulse rate of 130 bpm, and blood pressure of 130/85 mmHg. Chest auscultation revealed bilateral diffuse coarse crackles. The chest x-ray is shown in Box 1, and results of additional investigations in Box 2. Despite treatment with broad-spectrum antibiotics (intravenous ceftriaxone, dicloxacillin and erythromycin), the patient’s condition deteriorated rapidly, and he required intubation within 24 hours of presentation. Trap sputa contained abundant thin, partially acid-fast, beaded, branching filaments, suggesting Nocardia asteroides, which was later confirmed on culture using conventional biochemical testing. Several blood cultures taken on admission also grew N. asteroides. All cultures for mycobacteria were negative. The patient was treated with intravenous trimethoprim–sulfamethoxazole for a total of 5 weeks and oral minocycline for 14 weeks. He spent 6 weeks in hospital. Liver biopsy, performed because of persistently abnormal hepatic function at follow-up 8 weeks after hospital discharge, showed central fibrosis and non-caseating granulomatous hepatitis (Box 3). The patientn received no further treatment and remained well 18 months later, with almost normal hepatic function and a clear chest x-ray. Nocardia bacteraemia is rare, although the incidence appears to be increasing in the immunosuppressed. Nocardia spp. are seldom isolated in blood cultures, with one study finding that blood was the source of only 8% of all Nocardia isolates.1 Up to 30% of patients with Nocardia bacteraemia have coexistent infection with gram-negative bacteria.1,2 There has been one previous report of Nocardia pneumonia associated with positive blood cultures and liver disease. However, this patient had documented end-stage chronic liver disease at presentation, was taking prednisolone, and developed nocardiosis after prolonged hospitalisation with gram-negative sepsis.1 Granulomatous reactions are well described in Nocardia infection. Although granulomatous hepatitis is also described in sarcoidosis, it is rare and usually presents with itch and obstructive abnormalities of liver function.4 In our patient, acute N. asteroides infection was the most likely cause of both the pulmonary infiltrate and the granulomatous hepatitis. Not only were results of modified acid-fast stains consistent with Nocardia spp., but cultures from multiple trap sputa and blood specimens also grew N. asteroides, suggesting a large load of this organism. No other organisms were isolated despite prolonged incubation of cultures, and the patient recovered after specific treatment directed at Nocardia spp. Furthermore, he remained well with no further treatment at 18-month follow-up, with near-normal hepatic function and no new abnormalities. We conclude that N. asteroides infection can present as a fulminant community-acquired pneumonia with bacteraemia in the absence of immunosuppression or coexistent infection. Our case illustrates the potential hepatic sequelae of Nocardia bacteraemia. 1: Chest x-ray of a patient with Nocardia asteroides pneumonia Chest x-ray taken on admission to hospital, showing widespread non-symmetrical interstitial and airspace infiltrates. 2: Results of investigations Result Reference range At presentation Arterial blood gases* pH 7.37 7.35 –7.45 pCO2 (mmHg) 43 35 – 45 pO2 (mmHg) 60 75 –105 Bicarbonate (mmol/L) 24 24 – 31 Base excess 0 − 3 to 3 White cell count Total (x 109/L) 31.5† 4 –11 Neutrophils (x 109/L) 30.2 2 – 7.5 Lymphocytes (x 109/L) 0.7 2 – 4 Follow-up at 8 weeks Liver function tests‡ Bilirubin (μmol/L) 9 < 18 Alkaline phosphatase (U/L) 124 30 –100 γ-Glutamyl transferase (U/L) 153 < 35 Iron studies Serum ferritin (μg/L) 446 30 – 400 Serum iron (μmol/L) < 3 10 – 30 Transferrin (g/L) 1.9 2.0 – 3.5 Transferrin saturation < 6% 15%–50% Vitamin B12 (pmol/L) 376 > 126 Immunological tests HIV antibodies Negative Hepatitis B and C§ Negative Autoantibody screen¶ Negative Complement C3 (g/L) 1.07 0.82 –1.45 Complement C4 (g/L) 0.25 0.15–0.45 * Breathing 10 L/min oxygen. † Occasional myelocytes, toxic granulation. ‡ Levels of alanine and aspartate aminotransferase were in the reference range. § Including hepatitis B surface antigen and hepatitis C antibody. ¶ Including antinuclear, extractable nuclear antigen, double-stranded DNA and antineutrophil cytoplasmic antibodies. 3: Liver biopsy in a patient with Nocardia asteroides pneumonia Core biopsy of liver, showing a granuloma within the central portal triad (arrow); the portal ducts are expanded and fibrosed with a patchy lymphocytic infiltrate (original magnification x 40; haematoxylin and eosin stain).

Patricia A Figgis · Allan R Glanville · John L Harkness

Sam L S Yuen,* Bruce McGarity† * Medical Registrar, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050; † Physician, Bathurst Base Hospital, Bathurst, NSW. lsyuen_98ATyahoo.com To the Editor: A 71-year-old man was admitted to hospital in 2002 with nausea, abdominal discomfort and myalgia. He was dehydrated and had mild right upper quadrant tenderness. No muscle tenderness was noted. Five weeks previously, an infected right femoropopliteal gortex graft had been surgically removed. Methicillin-resistant Staphylococcus aureus was present on culture. Therapy with fusidic acid (250 mg three times daily) and rifampicin (600 mg daily) had been commenced, and the patient’s condition improved. Fusidic acid therapy was continued because of unsatisfactory wound healing. On presentation he had been taking fusidic acid for 4 weeks. He had been taking simvastatin (40 mg nightly) for 8 years. The patient had a history of generalised vascular disease and multiple bypass procedures. He had a background of paroxysmal atrial fibrillation, myocardial infarction, left ventricular failure, hypertension, hypercholesterolaemia and chronic airways limitation. His other medications were metoprolol, irbesartan, frusemide, warfarin, paracetamol and narcotic analgesics. Test results showed the following biochemical concentrations: aspartate transaminase, 1618 U/L (normal range, < 40 U/L); alanine transaminase 657 U/L (normal range [NR], < 35 U/L); alkaline phosphatase 133 U/L (NR, 25–100 U/L); total bilirubin, 29 μmol/L (NR, < 20 μmol/L); γ-glutamyltransferase, 37 U/L (NR, < 50 U/L); urea, 24.7 mmol/L (NR, 3.0–8.0 mmol/L); creatinine, 0.35 mmol/L (compared with previous creatinine concentration of 0.11 mmol/L [NR, 0.06–0.12 mmol/L]). Drug hepatitis, secondary to fusidic acid was suspected, and therapy with this drug was ceased. The following day, the patient’s clinical status declined, with generalised muscle pains and weakness, significantly impairing his mobility. The serum creatine kinase concentration was elevated at 66 710 U/L (normal range, 60–220 U/L), with a normal troponin I concentration. Myoglobinuria (567 200 ng/mL) was detected. Simvastatin therapy was ceased, and there was prompt clinical improvement, with recovery of renal function and a gradual fall in the concentration of serum creatine kinase. On discharge 14 days after admission, his serum creatine kinase concentration was 1153 U/L and creatinine concentration was 0.12 mmol/L. Transaminase concentration readings fell rapidly in line with the creatine kinase concentration, suggesting they were of muscular rather than hepatic origin. Three other cases of rhabdomyolysis have been reported as a result of interaction between an HMG CoA-reductase inhibitor and fusidic acid,1-3 but there have been no previous reports from Australia. Fusidic acid, like simvastatin, undergoes extensive first-pass metabolism in the liver (over 98%). Simvastatin is metabolised via the cytochrome P3A4 enzyme system. It is known that, if given concomitantly with inhibitors of this system (eg, macrolides and azole derivatives), statin concentrations can become elevated and lead to an increased likelihood of adverse effects.4 Fusidic acid is not known to be an inhibitor of this system (Peter Hobbs, Manager of Medical Affairs, CSL Limited [manufacturers of fucidin], personal communication), although our case is suggestive of such an interaction. This case demonstrates the interaction of fusidic acid with simvastatin resulting in rhabdomyolysis. The extensive use of statin therapy in patients with vascular disease makes it important for doctors to be aware of this interaction when prescribing fusidic acid.

Sam L S Yuen · Bruce McGarity

Andrew G Marsden Occupational Physician, Unit 6, 125 Melville Parade, Como, WA 6152. To the Editor: Modern air travel lends itself to aerosol transmission of viral infection. Infected individuals in modern aircraft represent a significant risk for other travellers during long journeys. In September 1999, a person with an influenza-like illness joined other workers returning by aircraft to an isolated mine in north-western Australia. He was identified as unwell by a mine supervisor in the airport lounge but was allowed to board the BAe 146 aircraft (a 75-seat passenger jet aircraft). The flight lasted 3 hours 20 minutes. On landing in the evening, most workers were transported to their quarters in a 10-minute bus trip, but some, including the affected worker, travelled independently. They then went to their individual rooms. The next day, the affected worker reported sick immediately on going to his work site and did not work for 4 days. The other workers undertook 12-hour shifts operating machinery or in offices, relatively isolated from other people. However, they may have mixed socially. Over the next 3–4 days, 15 other workers presented with an acute influenza-like illness, with fever, cough, nasal congestion, anorexia and prostration. No serological tests were undertaken because of the remoteness of the mine. All other workers on the flight were contacted by telephone 6 days after the flight. Five more were identified who had significant upper respiratory tract symptoms and were taking simple analgesics, but had continued to work. The airline reported that no staff from the aircraft had reported sick over the next week or so. The seating positions of the affected workers on the aircraft, which was full, are shown in the Box. The index patient sat in seat 11G. Most of the other affected workers appeared to sit in a “plume” around him. The only affected workers who sat further away were the supervisor who assessed the index patient in the airport lounge (seat 3A) and a person who conducted a raffle during the flight and walked the length of the aircraft collecting money and ticket stubs (seat 1F). In aircraft such as the BAe 146, air is circulated and filtered, entering the passenger compartment through continuous vents just beneath the overhead lockers, circulating downwards and exiting from continuous vents under the seats. Air therefore tends to flow in two contrarotating circles, from ceiling to floor on either side of the aircraft. Infection could well have been transmitted by aerosol droplets to passengers behind the index patient, as he coughed and sneezed throughout the flight. The immunisation status of the passengers was not recorded; most were aged 20–45 years. This outbreak was relatively confined, as the passengers were in an isolated community, and those affected were managed in their rooms. However, the implications for the spread of airborne infection in passenger aircraft and into the wider community are obvious. It must be stressed to the travelling public that people with this type of illness should not fly. Airport authorities at passenger check-ins should be encouraged to identify and formally assess potentially infected individuals, and should have the authority to take precautions against spread. Aircraft seat allocations of index patient and affected passengers I = index patient. F = passenger developed influenza-like illness. M = passenger developed mild upper respiratory tract illness.

Andrew G Marsden

John M Weiner Allergist, Department of Respiratory Medicine, St Vincent’s Hospital, Fitzroy, VIC 3065. jmweinerATallergynet.com.au To the Editor: Any doubts that many Australian doctors are prescribing inhaled fluticasone for asthma at inappropriately high doses are dispelled by the three reports in the 3 March issue of the Journal.1-3 Fluticasone has a flat dose–response curve for efficacy and a steep dose–response curve for adverse effects;1 individuals with asthma are receiving high doses of inhaled fluticasone;2 and there is a potential for the effects to be lethal.3 Each of these reports restricted its advice to negative recommendations about drug treatment (DON’T overtreat, BACK-titrate), but this is the right time to also promote positive recommendations about asthma management. All individuals with persistent asthma requiring daily therapy should have either skin testing or in-vitro testing to determine the presence of specific IgE antibodies to inhalant allergens.4 This might allow the option of allergen avoidance. In some studies, dust mite reduction was found to ameliorate asthma symptoms in sensitised individuals (National Health and Medical Research Council Level II evidence), although those findings are not supported by a meta-analysis. Repeated low-dose exposure to cat allergen in cat-allergic individuals with asthma leads to increased non-specific bronchial hyperreactivity (Level II evidence).5 Allergen desensitisation in carefully selected cases with consultant supervision can lead to a significant reduction in medication requirement, and reduced specific bronchial hyperreactivity (Level I evidence).6 Treatment of concomitant rhinitis can itself lead to easier asthma control. A checklist of the “A,B,C...” of asthma triggers does not take long and often yields useful tertiary prevention strategies: Allergy (seasonality, dust, pets), Bronchial infection, Cold air/exercise, Drugs, Emotion/stress, Food and food additives, Gastro-oesophageal reflux, Hormones and pregnancy, Irritants including cigarette smoke, and the Job. Inhaled anti-inflammatory treatment using cromolyns or corticosteroids, with or without consideration of oral montelukast, remains the cornerstone of asthma control when the disease is frequent or persistent. However, the search for allergic and other triggers by healthcare workers, individuals with asthma, and their carers can instil into the entire group a culture of prevention, which naturally leads to a brake on overtreatment. Such a culture is firmly entrenched in continental Europe and the United States. In Australia, there has been outstanding research into the epidemiology and immunology of asthma, but it’s at the coalface where the individual with asthma gets advice. A diligent search for triggers, with appropriate management, should start at the first consultation, as the pen (or mouse) is poised to prescribe.

John M Weiner

Jill S Butty Quality Facilitator, Werribee Mercy Hospital, 300 Princes Highway, Werribee, VIC 3030 jbuttyATmercy.com.au To the Editor: It was refreshing to see the report by South et al, describing a simple, inexpensive intervention which resulted in a positive effect on the appropriate prescribing of antibiotics and a cost saving for the organisation.1 In the current climate, it has been much more fashionable to suggest computerised prescribing as the cure-all for medication and prescribing errors. As demonstrated by Newby et al,2 computerised prescribing has inherent problems, including an increase in repeat ordering of antibiotics. The Australian Council for Safety and Quality in Healthcare suggests computerised prescribing as one of several strategies to reduce medication critical incidents.3 However, the costs of establishing such a system in smaller hospitals and community health centres can prove prohibitive. This can lead to an attitude of “too expensive” so do nothing. Other strategies and interventions can be introduced at minimal cost to the organisation and yet prove effective in reducing both inappropriate prescribing and the number of critical incidents or errors. The provision of easily accessible standardised protocols and guidelines, the review of medication charts and their ease of use, changing the times of daily medication administration to maximise access to clinicians, and empowering patients to be more aware and responsible for their medications are just a few. In summary, other strategies need to be developed and their success or failure reported. There should also be awareness that familiarity with procedures can lead to errors and reinforcement is required for all interventions. Computerised prescribing should not be viewed as the solution to all medication adverse events, but one of several strategies that healthcare organisations can use in their battle with medication errors.

Jill S Butty · Saji S Damodaran

Saji S Damodaran Associate Professor, Department of Psychological Medicine, Monash University, and Clinical Director, Monash Medical Centre, 246 Clayton Road, Clayton, VIC 3168 saji.damodaranATmed.monash.edu.au To the Editor: Australia has a high rate of antibiotic use. Increasing antibiotic resistance, spiralling pharmaceutical cost, need for evidence-based practice, public awareness, and widespread variation in prescribing practice, which may lead to quality and safety issues, are reported as the drivers for improving antibiotic use and prescribing. South et al are to be commended for the introduction of a laminated card for doctors as a simple intervention to improve prescribing practices.1 Despite the passive nature of the intervention, they found significant improvement in the appropriateness of prescribing. The authors acknowledge that they are not claiming that their intervention “is the cause or only cause” for change in practice. Areas like antibiotic prescribing and physician behaviour are highly complex and require a series of systematic approaches. Doctors are only one of the multiple stakeholders involved in this process. The level of experience, training background, and awareness of the public health and clinical implications of such interventions vary widely among doctors. Improvement of South et al’s methodology from a passive mailout to gathering systematic baseline information about the medical staff involved, clarifying the purpose of the initiative and finding the proportions of uptake among junior and senior staff would have made the intervention more robust. One of the fundamentals of any change process is to instil a sense of urgency and develop a coalition to drive and lead it. Development and evaluation of quality initiatives need more than just passive information provision. It has been suggested that any such quality and safety initiative should have set priorities, and these priorities should be developed using a systematic evaluation process with explicit criteria.2 Various systemic strategies that involved systematic methodology and evaluation processes, such as antibiotic decision support systems (both computer and manual) and drug utilisation reviews, reported sustainable changes in prescribing practices.3 The intervention by South et al is a welcome initiative, but it is important to realise that simplifying a complex problem like drug prescribing may lead to setting up wrong priorities for action and trivialise the problem and solution. Such initiatives will suffer the fate of the many quality programs that we hear about in hospital corridors but which fail to make a sustainable change.

Stephen C Due Editor, AMPI, Geelong Hospital Library PO Box 281, Geelong, VIC dueATbarwonhealth.org.au Readers interested in medical history may like to know about the Australian Medical Pioneers Index (AMPI), which is the first major Australian medical history website, and the first published encyclopaedia of Australian medical biography. AMPI aims to provide basic personal and professional information on every doctor resident in Australia, or professionally connected with Australia, up to the year 1875. This includes medical officers on immigrant and convict ships, doctors who practised in Australia, and doctors who pursued other occupations here. Over 3000 pioneer doctors are listed. In addition to biographical data, the website provides interesting material on the medical profession in colonial times, including a picture gallery containing rare images of pioneer medical life (Box). There is also a section on sources of information about early doctors. The original compiler of AMPI was Dr David Richards (1937–1998) of Nottingham, England, whose card file was computerised at the Geelong Hospital Library. The website was developed in conjunction with the State Library of Victoria as a community service. Anyone with additional data about a particular doctor is encouraged to contribute to the project. Colonial medical transport. Dr S R Robinson adopted this modern mode of transport when most of his colleagues still kept horses and buggies. (Geelong Heritage Centre — reproduced with permission.)

Stephen C Due

Mai Maddisson General Practitioner, Mitcham North Clinic, 188 Mitcham Road, Mitcham, VIC 3132. mmaddisson.nmcATwdgp.com.au To the Editor: I read with interest McFarlane’s article on post-traumatic stress disorder and debriefing,1 which reminded me of a long-term patient. Over a decade ago, I discovered that this patient was a Vietnam veteran, and expressed concern that he had not told me previously. His reply came thus (although, of course, I no longer remember the exact words): “How would you know what it feels like to be, by sheer chance, the only man left alive in a group of soldiers?” I acknowledged that he was correct, that I had no idea. With that poignant remark in mind, I planned his care. He is doing OK. Can we really address an abstraction that we cannot conceptualise, or predict the resulting obstacles in a person’s journey through life? This is equally valid at the beginning of the journey or anywhere along its course. Perhaps the notion of debriefing at an appropriate time is not the problem; perhaps it is the formula we use.

Mai Maddisson

Peter J Collignon*, Dianne E Dreimanis† and Wendy D Beckingham† *Director, Infectious Diseases Unit and Microbiology Department; †Clinical Nurse Consultants, Infection Control; The Canberra Hospital, PO Box 11, Woden, ACT 2606. peter.collignonATact.gov.au To the Editor: Single-use devices (SUDs) are in common use, and many are reprocessed.1-7 When examined, these devices are frequently not clean and have residual biological material on or within them.2-4,6 This material may contain viruses or other infectious agents. SUDs are usually made from plastics or other heat-sensitive materials resulting in less effective means being used for sterilisation than can be used for more robust materials — chemical disinfectants can be ineffective in the presence of organic material, and have poor penetration compared with heat (eg, an autoclave). In 1994 we found that, of 168 Australian hospitals reviewed, 68% were reprocessing SUDs used in sterile sites.1 We repeated this survey (using a similar questionnaire) in 2001, in acute-care hospitals with more than 45 beds. The questionnaire was sent to 461 hospitals — 181 private hospitals (117 with fewer than 100 beds, 59 with 100–300 beds, and five with more than 300 beds) and 286 public hospitals (115 with fewer than 100 beds, 116 with 100–300 beds and 55 with more than 300 beds). Responses were received from 189 (see Box 1). Not all respondents answered all questions and many responded anonymously. Reuse of SUDs still occurred in all states and territories, but compared with 1994 the rate had dropped to 15% (28 hospitals). Large hospitals reused more often than smaller hospitals (see Box 1). Reuse was slightly lower in private hospitals than in public hospitals (13% v 16%). Rural hospitals reused SUDs less often than metropolitan hospitals (12% v 16%). The commonest SUDs reused were diathermy pencils. Given their low cost ($5), the labour costs of reprocessing would exceed the cost of replacement. Diathermy pencils (Box 2) have spring-loaded buttons, which inevitably become contaminated with blood during surgical procedures. Thus, the potential exists to contaminate the surgeon's fingers during subsequent procedures. We believe that reusing such relatively inexpensive items is inappropriate from both financial and infection control perspectives. An Australian National Health and Medical Research Council (NHMRC) report stated that, after reprocessing and packaging in hospitals, almost all SUDs were contaminated with foreign material (including blood), and several pacing electrodes had damaged insulation.6 Other studies have shown that blood persists on cardiac ablation catheters when structural abnormalities (which occurr frequently and early) are present.3 The reuse of these devices has been reviewed by the NHMRC and important changes have been recommended.6 Reuse of SUDs has been common in many countries. In the United States, reprocessing is frequent (eg, 2.5 million devices by one commercial reprocesser).5 In 2000, the US Food and Drug Administration issued a policy that, for practical purposes, should abolish the practice of reprocessing SUDs in hospitals.4 In Australia, the Therapeutic Goods Administration recently announced that reprocessing of SUDs will be regulated.7 This should have a similar effect. As the methods and response rates of our two surveys were similar, we believe that the reuse rate has decreased. However, proportionately, fewer large public hospitals responded (only 13 of 55, or 24%, compared with 41% overall), even though they have the highest reuse rate (54%). Therefore, we are likely to have underestimated the actual rate of reuse. Also, those who are reusing may be less likely to admit to this practice, and thus less likely to respond. Reuse of SUDs in sterile sites remains common practice in Australian hospitals (although the rate is lower than it was in 1994). Most SUDs appear to be unsuitable for reuse as they cannot be adequately cleaned and sterilised. We strongly advise against further reuse of these items. 1: Number and types of hospitals reusing single-use medical devices Number reusing devices / Number respondents Bed numbers Type of hospital Unknown < 100 100–300 > 300 Total respondents Unknown 0/1 0/2 1/4 1/1 2/8 (25%) Public 0/1 5/41 4/44 7/13 16/99 (16%) Private 4/40 6/36 0/2 10/78 (13%) Combined public and private 0/2 0/2 0/4 Total respondents 0/2 9/85 (11%) 11/86 (13%) 8/16 (50%) 28/189 (15%) 2: A diathermy pencil

Peter J Collignon · Dianne E Dreimanis · Wendy D Beckingham

Clifford F Hughes Head, Department of Cardiothoracic Surgery, Royal Prince Alfred Hospital, Suite 304, 100 Carillon Avenue, Newtown, NSW 2042 clifford.hughesATemail.cs.nsw.gov.au Comment: The letter by Collignon, Dreimanis and Beckingham about reuse of single-use medical devices (SUDs) in Australian hospitals again brings in to stark contrast the issue of safety and quality of medical devices and the pressing need to provide affordable services to the Australian public. Seven years ago, Collignon and colleagues showed an unacceptably high reuse of SUDs in Australia, especially in public healthcare institutions.1 Since then, the National Health and Medical Research Council (NHMRC) has produced an expert panel report on these devices2 and the Therapeutic Goods Administration has promulgated detailed device regulations.3 There has been continued debate in both the scientific literature and lay press, and the United States Food and Drug Administration has had extensive comments published on this matter.4,5 Given the intensity of this debate, it is surprising that so few hospitals completed the questionnaire. It is also surprising that, despite the overall reduction in the reuse of SUDs, there has been no apparent reduction in their use in large public institutions, 50% of which continue the practice. Collignon and colleagues have not investigated the quality control mechanisms in place in these hospitals. That could well be a subject for further research. Not so obvious to the casual user is the effect of resterilisation on the materials of the device. The authors allude to the potential for degradation during sterilisation. There is inevitable pressure to use less effective (chemical) means for re-sterilisation. On the other hand, the waste of an enormous resource that, if safe, could be readily reused must be recognised. The costs of devices are easy to quantify. The costs of resterilisation, not to mention quality control, less so. Collignon et al suggest one example of false economy in the reuse of a low budget but commonly used item — diathermy pencils. They make a strong case for mandated reporting of resterilisation protocols for all single-use items. Informed consent must be a prerequisite. Tracking systems could well provide beneficial information on the safety and efficacy of procedures for particular devices. Furthermore, clinical audit would provide an early warning mechanism should resterilisation prove inadequate. These are among the main recommendations of the Report of the NHMRC Panel.2 Extensive regulations and controls have been applied to the use of biological products such as dura mater, heterograft and cardiac valves, among others. There is, however, reluctance to apply similar stringent controls to devices which may be contaminated by more pervasive but less obvious biological hazards. There are only three options: cease this practice wherever a viable alternative is available until there is incontrovertible proof of the safety of reuse; mandate detailed protocols which include audit and surveillance mechanisms coupled with appropriate informed consent whenever SUDs are reused;2 and develop a research and evidence base for improvements in design and materi-al technology so that the "cost efficiencies" of single-use devices could be translated to "nondisposable items". All three must be adopted.

Clifford F Hughes

Graeme H Johnson*, Donna B Mak†; *Acting Public Health Medical Officer; †Former Public Health Medical Officer, Kimberley Population Health Unit, Derby, WA 6728. graeme.johnson@health.wa.gov.au To the Editor: In their study of a SAFE-style trachoma control program (which included Antibiotic treatment, Facial cleanliness, and Environmental improvement, but not Surgery) in a remote Australian community, Ewald et al suggest that no systematic SAFE trachoma control program exists in Australia.1 In the Kimberley region of Western Australia, the Kimberley Public Health Unit (KPHU) has coordinated a trachoma control program since 1989. The World Health Organization SAFE strategy has been implemented since 1996, as described in the Kimberley regional trachoma control guidelines and a peer-reviewed publication.2,3 The trachoma control program in the Kimberley has been delivered by a variety of environmental health, health promotion, community and clinical health professionals employed by State and local governments, and by community-controlled and other non-government organisations. We believe a coordinated regional approach is mandatory, because of the numerous organisations involved in program delivery. The trachoma control program in the Kimberley continues to achieve good results. The prevalences of follicular trachoma during annual screening of school-aged children in the Kimberley have been published annually in the KPHU Bulletin.4 Since 1996, in accordance with the WHO SAFE strategy, communities with trachoma prevalences of less than 5% were not screened in subsequent years and did not contribute to regional prevalence data. Thus, the observed decrease in trachoma prevalence between 1996 and 2001 is likely to be greater than that shown in the Box. We believe the Kimberley region is well placed to achieve the WHO aim of eradicating blinding trachoma by 2020.5 However, it is a concern that other regions of Australia with endemic trachoma infection may not conduct disease control activities in a coordinated manner because of lack of leadership in trachoma control or insufficient resources, or both. The community described by Ewald et al borders the Kimberley region and has strong cultural links with several Kimberley groups. The achievements in trachoma control in the Kimberley cannot be sustained in the long term without a nationally coordinated approach. We believe that it falls within the statutory responsibilities of State and Territory departments of health to ensure that environmental and clinical health services are coordinated to achieve trachoma control in Australia. Trachoma in Kimberley children Point prevalence of follicular trachoma among children in the Kimberley region aged 5–15 years at annual trachoma screening, 1991–2002

Graeme H Johnson · Donna B Mak

Andrew C Laming,* Bart J Currie† * Advisor, Federal Minister for Health and Ageing, Parliament House, MG 48, Canberra, ACT 2600; † Professor in Medicine, Northern Territory Clinical School and Menzies School of Health Research, Darwin, NT. andrew.lamingAThealth.gov.au To the Editor: The important article by Ewald et al shows that offering azithromycin treatment to 70% of a remote community may be inadequate to control hyperendemic trachoma, even when combined with a health promotion campaign.1 Yet, significant short-term gains in similar locations have been achieved with as little as 20% of the population receiving azithromycin, where administration to children with trachoma and their household contacts was directly observed by health staff.2 In that study,2 we reported a 6-month follicle resolution rate in schoolchildren of 72%, followed, however, by a return of trachoma prevalence towards baseline levels over 12 months. The critical factors for short-term success with azithromycin appear to be appropriate selection of cases and contacts, plus, where possible, directly observed therapy to minimise reinfection from untreated cases. Sustainability of initial reduction in trachoma prevalence is problematic, and issues of how extensively and how often to screen and/or treat need to be determined in the Australian context. Similar sustainability considerations have arisen in community scabies programs.3 Ewald et al are correct to identify population mobility as a major issue, with trachoma likely to be reintroduced by untreated children entering a community where a treatment program has occurred. Hence the need for a coordinated regional approach. However, a regional approach to trachoma control does not necessarily mean a uniform approach, and it is vital to tailor programs to suit the capacity of communities and their degree of commitment to labour-intensive treatment and health promotion. Our study suggested that directly observed twice-yearly azithromycin therapy, with a health promotional component, is likely to be preferable to an annual program.2 Mathematical modelling supports this more frequent dosing and, unlike in Africa, the cost of azithromycin should not be a constraining factor in Australia.4 Regardless of the strategy selected, if, after treatment, the prevalence remains hyperendemic (> 20%), then the outcomes from concurrent health promotion are compromised. Appropriately targeted and directly observed azithromycin therapy can help create conditions favourable for health promotion campaigns, which in turn prolong those gains by reducing trachoma transmission.5 Major issues for trachoma control in Australia are (i) who to screen and treat (with directly observed azithromycin therapy); (ii) how often to screen and treat; (iii) how to plan trachoma programs as regional initiatives; and (iv) who will fund, coordinate and implement trachoma programs.

Andrew C Laming · Bart J Currie

Dan P Ewald,* Gillian V Hall,† Christine C Franks‡ * Senior Research Fellow, Centre for Remote Health, Flinders University, PO Box 4066, Alice Springs, NT; † Lecturer, National Centre for Epidemiology and Population Health, Australian National University, Canberra, ACT; ‡ Educator, Health Development, Health and Community Services, Alice Springs, NT. dan.ewaldATflinders.edu.au In reply: These letters reinforce a number of important points about control of trachoma (and other endemic infections) in Australia. The questions of whom and how often to treat need refining through Australian experience. Long-term control needs multifaceted, intersectoral collaboration to alter environmental and behavioural conditions against disease transmission. Strategies should be sustained, regional (large as practicable); acknowledging, and guided by, Aboriginal kinship networks; and recommend observed drug treatment (which was negotiated for the final treatment in our study). A non-uniform approach could include more frequent treatment in hyperendemic communities, probably leading to less net use of antibiotic treatment. Reports from the Kimberley Population Health Unit show a very mixed picture, with wide year-to-year fluctuations in prevalence in many communities. While hyperendemic communities remain in a region, the prevalence of trachoma may increase unnoticed in communities no longer screened because their prevalence has dropped below 5%. If not looked for, it is unlikely to be noticed. Further analysis, such as the graph provided by Johnson and Mak, is to be applauded in the context of a thorough analysis. When this happens, it will greatly strengthen the case for active trachoma control in other regions. For trachoma prevention, and for many other reasons, we believe environmental health interventions are critical. These remain difficult to evaluate given the high mobility of people in Aboriginal communities. Reliable, long-term, regional environmental health and mobility data are needed as part of this broad issue.

Dan P Ewald · Gillian V Hall · Christine C Franks

Richard X Davey Chemical Pathologist, Melbourne Health Shared Pathology Service, Pathology Department, Western Hospital, Footscray, VIC, 3011. richard.daveyATwh.org.au To the Editor: Stone and colleagues must be complimented for their study of gestational diabetes mellitus (GDM) published recently in the Journal.1 Although the study was comprehensive, in that it linked two pertinent records for 99.3% of the women delivering in Victoria in 1996, their analysis was necessarily limited to the parameters recorded in those two data sets. Stone et al do not refer to relevant recent work from Toronto, Ontario,2 and Sunshine, Victoria,3 which has already determined the maternal risk factors for GDM: increasing age, racial origin, family history of diabetes mellitus, and pre-pregnancy body mass index. Data on the latter two of these four factors were specifically noted as not available to Stone's group, but could have been mentioned as established risk factors to consider in patient management. The findings of Stone et al regarding age are similar to those previously reported. However, the relative risk for GDM in the Sunshine cohort increased from 25 years of age (odds ratio, 1.9; 95% CI, 1.3–2.7).3 Recasting the all-Victorian data1 with "< 25 years" as the reference datum would most likely produce a similarly significant result to that found in the Sunshine study. Again, the Victorian data on racial origin are but the Sunshine data writ large. Stone and colleagues had to choose a reference datum for this parameter, but have not avoided a problem that bedevils all such work in the "New World": there is as yet no definitive Australian reference datum available for racial origin. For example, the designation "Australian" may be used, but parents who are themselves second or third generation Australian-born may have, say, pure Maltese ancestry, giving them a high risk of GDM and thus distorting the reference datum. I have argued this case in more detail elsewhere,4 and took measures to circumvent the problem in the Sunshine study.3 Among their findings, Stone et al confirm that there is a significantly increased incidence of macrosomia in GDM-affected infants. I agree. Their work is unquestionably the definitive statement of Victoria's GDM-related macrosomia status (as at 1996), but it lacks one vital ingredient: it defines macrosomia, but does not cite the source of the data used as the study's benchmark. To enable comparisons with their work in future years, could we please have that benchmark referenced so that others may use it too?

Richard X Davey

Christine A Stone,* Kylie A McLachlan,† Jane L Halliday,‡ Peter Wein,§ Christine Tippett¶ * Epidemiologist, Prevention and National Health Priorities, ‡ Epidemiologist, Birth Defect Registry, Perinatal Data Collection Unit, Public Health Division, Department of Human Services, 17th Floor, 120 Spencer Street, Melbourne, VIC 3001; † Research Fellow in Endocrinology, Department of Endocrinology and Diabetes, St Vincent's Hospital, Fitzroy, VIC; § Senior Lecturer, Department of Obstetrics and Gynaecology, University of Melbourne, East Melbourne, VIC; ¶ Director, Maternal Fetal Medicine, Monash Medical Centre, Clayton, VIC. christine.stoneATdhs.vic.gov.au In reply: We thank Davey for his comments, which provide us with the opportunity to highlight the benefits and limitations of reports using population-based data. The value of population-based data is that the reported incidence, risk factors and outcomes reflect current practice in the whole of Victoria and are not subject to bias introduced by local referral patterns or clinical practice. Our study1 shows that, in addition to established risk factors for gestational diabetes mellitus (GDM), the reported incidence varies according to hospital size and geographic location, demonstrating the type of bias that can occur. In addition, the large number of subjects in our study (over 60 000) enables more accurate analysis of subgroups. A limitation, already highlighted in our discussion, is that we are restricted to the parameters available within the data sources used. Davey and Hamblin's article2 demonstrates the difficulty of obtaining individual patient data on body mass index, racial grouping, and family history of diabetes. Even working at the hospital level, they had to extrapolate from population-level data to derive an estimate of these risk factors among the control subjects.2 Given that their study population is a subgroup of ours,1 it is no surprise that the two studies showed similar results. An important implication for providers of health services is that, with increases in the age at which mothers give birth and in the number of births to Asian-born mothers,3 we predict that the prevalence of GDM in Victoria will rise. Davey correctly points out that our article does not refer to a relevant 1997 study by the Toronto group.4 However, we do actually refer to a later publication by the same group.5 The problem of ethnicity and migration arises in studies of conditions that are not only polygenic but also a result of complex interactions between a person's genes and his or her environment. Lastly, the source of information on macrosomia was 1996 population data. We have since produced a percentile chart of weight (g) for gestational age (weeks) based on 15 years of Victorian data.6

Christine A Stone · Kylie A McLachlan · Jane L Halliday · Peter Wein · Christine Tippett

Michael Copeman Paediatrician, Department of Paediatrics, Manly and Mona Vale Hospitals, Darley Road, Manly, NSW 2095. mcopeman@bigpond.net.au To the Editor: Law and Batey1 rely on a flawed study for their conclusion that needle/syringe programs (NSPs) have saved lives and money. The study in question2 compared the incidence of HIV and hepatitis C virus (HCV) infections in cities round the world and concluded that cities with NSPs had achieved reductions in HIV incidence that were not seen in cities without NSPs. However, interestingly, no similar reduction in HCV incidence was reported. Detailed reading of the study shows that a third of the cities (22/67) without NSPs were in Thailand — a country in which, unfortunately, there are many other reasons why HIV incidence is increasing rapidly. Given the large proportion of Thai cities included in the study, it is plausible that the rapid rise in HIV incidence in these cities biased the overall results of the study, leading to an erroneous conclusion that NSPs themselves were associated with a reduction in HIV incidence in cities worldwide. Further reading of the study shows that HCV incidence was not measured in any studies in Thailand. So, the reported lack of effect of NSPs on HCV incidence depends on comparisons between cities with and without NSPs from other parts of the world, perhaps less affected by some of the problems in Thailand. In conclusion, if Thai cities had been excluded from the study, it seems likely that no change in the incidence of either HCV or HIV might have been found in association with NSPs. The original study needs urgent re-analysis to see if this is in fact the case.

Michael Copeman

Matthew G Law,* Robert G Batey† Statistician, National Centre in HIV Epidemiology and Clinical Research, University of New South Wales, 376 Victoria Street, Darlinghurst, NSW 2010; † Clinical Chair, Division of Medicine, John Hunter Hospital, Newcastle, NSW. mlawATnchecr.unsw.edu.au In reply: Copeman's criticism of the report Return on investment in needle and syringe programs in Australia1 is essentially that the comparison of the effectiveness of needle/syringe programs (NSPs) is confounded by other factors. This point, and its implications for the results, was extensively discussed in that report. Copeman suggests that the estimated reduction in HIV due to NSPs might largely be attributable to the inclusion of data from many cities in Thailand that do not have NSPs. This criticism is not supported by the data. A sensitivity analysis including only cities from developed countries was performed at the time of the report (see Methods, Section 3.1.2, page 131), but was not included among the report's results because of space constraints and because it didn't alter the main findings. The analysis of cities in developed countries showed an overall mean reduction in the annual rate of change in HIV seroprevalence of –30.0%, compared with –24.7% based on all cities, albeit with lower statistical significance (P = 0.105 v P = 0.057), reflecting the loss in power through exclusion of cities. Copeman's assertion that the report indicated that NSPs had no effect on rates of hepatitis C virus (HCV) infection is incorrect. The report estimated that, following the introduction of NSPs, HCV prevalence among injecting drug users declined by 2% per annum, compared with no introduction of NSPs (P < 0.001). The report is freely available on the Internet,1 and we encourage readers to look at it for themselves.

Matthew G Law · Robert G Batey

Peter J Goadsby Professor of Clinical Neurology, Institute of Neurology, National Hospital for Neurology and Neurosurgery, Queen's Square, London, WC 1N 3BG, United Kingdom To the Editor: Gebski and Keech describe with clarity and accuracy the important basic concepts of statistical analysis for physicians.1 I would like to draw attention to two issues. Firstly, the authors refer to common measurement scales that are used in medicine. It is crucial to understand the limits of a measurement to begin to appreciate results from any study. They describe the continuous scale and offer blood pressure and temperature measurements as examples. This scale refers to data determined such that the distance between any two points is known and measureable. Siegel used the term "ratio scale" if there was a true zero point to the measurement.2 This contrasts to an ordinal categorical scale, in which the intervals are not constant. The scale referred to can be transformed, and is anchored with respect to the measurements to some reproducible point. The term "ratio" for this scale seems preferable, as the world is, in essence, discrete when measured, in the quantum sense. Certainly, the measured world is not continuous, at least as far as we can determine it. Secondly, the authors do not mention resampling methods.3 These can be very powerful and are attractive in biomedical research when the distribution may not be defined. While I realise these methods are relatively new, they do seem unreasonably ignored in undergraduate medical education.

Peter J Goadsby

Val J Gebski,* Anthony C Keech† * Principal Research Fellow, † Deputy Director, NHMRC Clinical Trials Centre, University of Sydney, Locked Bag 77, Camperdown, NSW 1450. valATctc.usyd.edu.au In reply: While one can view the world as being "discrete", the assumptions underpinning most common statistical methods in analysis of clinical studies are "continuous" distributions. In fact, statisticians go to enormous lengths to approximate discrete systems as continuous ones (lifetime analysis, normal approximations, etc). The measurement scale by which study outcomes are assessed needs careful consideration (to ensure consistent precision and units of measurement). However, both practical and statistical considerations allow for the more common definitions of continuous and discrete measurements to be just as effective for statistical comparisons. Indeed, there is frequently little loss of statistical efficiency when "continuous" variables are appropriately categorised into ordinal groups.1 Resampling methods randomly sample the data repeatedly to estimate the underlying population distribution parameters (eg, mean, standard deviation, etc). They can be very useful in solving specific problems in which the underlying properties of the data used to make treatment comparisons are unknown and using other statistical approximations is deemed to be inappropriate. However, these are specialised computer-intensive techniques for use by trained biostatisticians, rather than commonly used analysis methods. Problems arise with resampling techniques (eg, obtaining confidence intervals), which require specialised statistical expertise.

Val J Gebski · Anthony C Keech