Volume 169 Issue 4

Interval breast cancers in an Australian mammographic screening program Mary T Rickard, Richard J Taylor, Mohamed A Fazli and Nadima El Hassan MJA 1998; 169: 184-187 For editorial comment, see Rodger & Kavanagh Abstract - Introduction - Methods - Results - Discussion - Acknowledgements - References - Authors' details - - ©MJA1998 Abstract Objective: To determine the incidence of interval cancers which occurred in the first 12 months after mammographic screening at a mammographic screening service. Design: Retrospective analysis of data obtained by crossmatching the screening Service and the New South Wales Central Cancer Registry databases. Setting: The Central & Eastern Sydney Service of BreastScreen NSW. Participants: Women aged 40-69 years at first screen, who attended for their first or second screen between 1 March 1988 and 31 December 1992. Main outcome measures: Interval-cancer rates per 10 000 screens and as a proportion of the underlying incidence of breast cancer (as estimated by the underlying rate in the total NSW population). Results: The 12-month interval-cancer incidence per 10 000 screens was 4.17 for the 40-49 years age group (95% confidence interval [CI], 1.35-9.73) and 4.64 for the 50-69 years age group (95% CI, 2.47-7.94). Proportional incidence rates were 30.1% for the 40-49 years age group (95% CI, 9.8-70.3) and 22% for the 50-69 years age group (95% CI, 11.7-37.7). There was no significant difference between the proportional incidence rate for the 50-69 years age group for the Central & Eastern Sydney Service and those of major successful overseas screening trials. Conclusion: Screening quality was acceptable and should result in a significant mortality reduction in the screened population. Given the small number of cancers involved, comparison of interval-cancer statistics of mammographic screening programs with trials requires age-specific or age-adjusted data, and consideration of confidence intervals of both program and trial data. Introduction The principal aim of a mammographic screening service is to reduce mortality from breast cancer. As this outcome cannot be measured effectively for many years after the establishment of screening, and as it applies to spatially defined populations, a range of interim measures are used to evaluate screening services and to determine the likelihood of mortality reduction. Interim measures include screen-detected cancer rates and the rates of prognostic indicators for these cancers, such as size, nodal status and grade.1 Another interim measure of screening performance is the interval-cancer rate.2,3 As survival among women with interval cancers is similar to that among unscreened women, then as the incidence of interval cancers approaches that of the underlying incidence of breast cancer the benefit of screening disappears.3 Interval-cancer rates can be compared with background or underlying rates to better assess the effectiveness of screening. Further, comparing the rate of interval cancers with the underlying rate allows comparison between different screening programs in populations with different incidences of breast cancer. Our aim was to evaluate first-year interval breast cancers after screening at the Central & Eastern Sydney Service of BreastScreen NSW (a mammographic screening and assessment service). We report the incidence and proportional incidence of interval breast cancers during the 12 months after both the first and second rounds of screening, over five years. Methods The Central & Eastern Sydney Service of BreastScreen NSW is located in inner Sydney, and started screening in March 1988 as one of the first pilot mammography screening programs in Australia. Any woman aged 40 years or more was eligible to attend, although during the study period only 50-69-year-old residents in the Central Sydney Area Health Service were actively recruited for two-yearly screening. Since the progressive introduction of systematic, government-funded, population-based screening from 1991, the Service has become a regional component of BreastScreen NSW and BreastScreen Australia.4The study population comprised women who attended the Service for mammographic screening between 1 March 1988 and 31 December 1992. These women were all screened by two-view mammography. The technical quality of the Service's screening mammograms met all requirements for accreditation by BreastScreen Australia.5 All films were read independently by two radiologists and were reported as "normal" for routine rescreen or as "suspicious" and requiring assessment. The design of the screening and assessment Service has been previously described.6 Screen-detected cancers The definition of primary breast cancer used for this study includes invasive cancer and ductal carcinoma-in-situ (DCIS), but excludes lobular carcinoma-in-situ.5 All cases of primary breast cancer diagnosed by the screening and assessment Service in women attending for the first time were classified as prevalent (first-round) screen-detected cancers. Cancers in women attending for their first routine rescreen after two years were classified as second-round screen-detected cancers. Data were analysed according to age at first screen, by 10-year age groups (40-49, 50-59 and 60-69 years). Interval cancers We reviewed the data for interval cancers, defined as primary cancer of the breast diagnosed up to 12 months after a first-round or second-round screening mammogram in women aged 40-69 years at the time of screening. The date of diagnosis of these interval cancers was taken as the date of histological confirmation of cancer. Cases in which clinical and imaging findings were consistent with breast cancer but no surgery had been performed were included in the study and the date of diagnosis was taken as the date of cytological confirmation of cancer. Data were analysed by women's age at their first screen. Some interval cancers were reported to the screening Service and others were identified by linking the Service's screening database with the NSW Central Cancer Registry (NSW CCR), which has operated since 1972 as a population-based registry. Notification of malignant neoplasms has been a statutory requirement for all NSW public and private hospitals, radiotherapy departments and nursing homes since 1972, and for pathology and outpatient departments since 1985. The date of diagnosis used by the NSW CCR was defined as "date of first definitive treatment for cancer" during the period covered by this study, although incidence was designated mostly on the basis of the first notification (usually the biopsy report). We matched records of the screening database with the NSW CCR in late 1994 with the aid of probabilistic linkage7,8 using Automatch.9 Equivocal matches were investigated by individual examination of all details available, and by active follow-up by the screening Service. Positive linkages between the screening database and the cancer registry were investigated by the screening Service to ensure that all data on those interval cancers diagnosed in the first year after a negative screen were available for inclusion in the study. Statistical analysis The age-specific incidence of interval cancers was determined by dividing the number of interval cancers found in women screened between 1988 and 1992 by the age-specific (age at first screen) number of women screened over the same period. Age groups were 40-49, 50-59 and 60-69 years, although the latter two age groups are aggregated for reporting purposes. The underlying incidence of breast cancer from 1988 to 1992 was obtained by dividing NSW reported cases (as reported by the NSW CCR.10,11) by the State female population for the same three 10-year age groups. To express the interval-cancer incidence as a proportion of the underlying breast cancer incidence rate, an indirectly age-standardised incidence ratio12 was calculated using the State age-specific incidences as the standard. Because of small numbers of cases, 95% confidence intervals were derived by the Poisson method.12,13We compared our findings with those of studies from Sweden,3 the Netherlands14 and the United Kingdom15 using the 12-month interval-cancer data from the first two screening rounds for all studies except the UK study, for which only the first-round data were available. Confidence limits for interval-cancer rates from comparison populations were calculated from the published data using the same Poisson method as above. Results During the study period, the Central & Eastern Sydney Service carried out 39 988 first-round and second-round screens on women aged 40-69 years, and 226 screen-detected cancers were diagnosed. In the prevalent (first-round) screens, the screen-detected cancer rates per 1000 screens were 3.0 for women aged 40-49 years, 6.2 for 50-59-year-olds and 9.6 for 60-69-year-olds. Second-round rates were 3.5, 4.2 and 4.6, respectively. Eighteen interval cancers occurred in the first 12 months after screening. All of these interval cancers were invasive. The 12-month interval-cancer incidences are shown in Box 1. The underlying annual breast cancer incidences were 13.8 per 10 000 for the 40-49 years age group and 21.2 per 10 000 for the 50-69 years age group (19.4 for 50-59 years and 23.2 for 60-69 years). The interval-cancer incidences as a proportion of these underlying incidences are shown in Box 2, in which they are compared with those of the Swedish Two-County Study.3 The proportional interval-cancer incidence for women aged 50-69 years in the Central & Eastern Sydney Service (22.0%; 95% CI, 11.7%-37.7%) is compared with that for similar age groups from international studies3,14,15 in Box 3. The proportional interval-cancer incidence point estimate for the Central & Eastern Sydney Service was higher and had wider 95% confidence intervals than that of the Swedish Two-County Study (13.2%; 95% CI, 8.4-19.9), but was lower than that of the UK (31.4%; 95% CI, 24.9-39.1) and Dutch (39.5%; 95% CI, 20.4-69.0) studies. Discussion The screen-detected cancer rates achieved by the Central & Eastern Sydney Service exceed the National Accreditation Requirements and compare favourably with those reported from the Swedish Two-County Study and the other Australian mammographic screening services.5,16,17Our findings indicate that the first 12-month interval-cancer rate (as a proportion of underlying incidence) for women attending the Central & Eastern Sydney Service is higher than that of the Swedish Two-County Study,3 but lower than the rates reported from Nijmegen (the Netherlands)14 and North West Region UK.15 However, there is considerable overlap of 95% confidence intervals, and the conclusion must be that the Central & Eastern Sydney proportional first-year interval-cancer rate is not significantly different from that in these other studies. As a proportion of interval cancers occur because an abnormality has not been detected at the time of screening, the first-year interval-cancer rates reflect the proportion of false negative screens in the screening episode. The Central & Eastern Sydney results therefore indicate acceptable screening sensitivity and, as they are not significantly different from the results of the Two-County Study, they would be expected to indicate a similar future mortality reduction. The interval-cancer data presented in this study are not affected by significant ascertainment bias. Restricting our analysis to interval cancers occurring within the first year after a screen eliminates the difficulties of accurately differentiating interval cancers and screen-detected cancers diagnosed around the 21-27-month rescreen interval. We directed considerable attention to the linkage with the NSW CCR to ensure that no interval cancers were missed. The underlying rate of breast cancer is reliable. This was determined in a population that included the women who were screened. However, during the study period, the Central & Eastern Sydney BreastScreen Service was one of only two pilot mammographic screening and assessment endeavours in New South Wales, and screened a small fraction of the State's female population. Its clientele was not limited to the immediate geographic area. For the busiest years in this period (1991 and 1992) less than 5% of breast cancers in NSW were detected through these two mammographic screening services.18 Completeness of enumeration is difficult to determine precisely for cancer registries, but the standard indicators suggest reasonably good completeness for the NSW CCR,10,19 and its data are accepted for inclusion in Cancer incidence in five continents.20 Comparisons of the Central & Eastern Sydney Service and another pilot mammographic screening service with the NSW CCR for the period 1988-1992 showed 100% enumeration of invasive breast cancer by the NSW CCR (R T, NSW Cancer Council, unpublished data). The design of the Australian mammographic screening program and the comparison studies in this paper differ. The Swedish Two-County Study employed single-view mammography and double reading. The Dutch and UK studies used single-view mammography and single reading. Double-view mammography and double reading, as used in Australia, would be expected to produce better results and fewer interval cancers in the first year than the comparison studies. The confidence intervals of the proportional interval-cancer rates from the Swedish Two-County Study and those reported for North West Region UK do not overlap, and direct statistical testing has shown a significant difference between these rates.15 The authors of the UK article15 and those of the accompanying editorial21 expressed concern that the screening sensitivity in the British National Health Service program may not be sufficient to achieve mortality reduction targets. They noted the increased sensitivity resulting from two-view mammography, good film quality and two independent film readings. These features are part of BreastScreen Australia and of the Central & Eastern Sydney Service. Even when data are collected over reasonable lengths of time, the numbers of interval cancers in many screening services are often small because of the size of the base populations. In the 50-69 years age group, there were 23 interval cancers in the Swedish Two-County Study, compared with 12 in the Nijmegen study and 13 in our study. However, performance can still be evaluated through calculation of interval-cancer rates, provided that interpretation is qualified by consideration of confidence intervals based on exact or Poisson methods. Australian mammography screening services are evaluated by comparison with National Accreditation Requirements standards.5 The point estimate of the Swedish Two-County Study has come to be regarded as a standard, as this study achieved significant mortality reduction. However the Two-County Study did not involve large numbers, and its interval-cancer rates must be interpreted in relation to their statistical confidence intervals. That is, standards cannot be derived from point estimates alone as they emanate from real studies in real populations. Further, comparison of the performance of screening services with such standards also requires that the confidence intervals of the screening service data be taken into account. Evaluations should not be based on point estimates of rates which derive from small numbers with considerable stochastic variation. The standard for Australian National Accreditation Requirements is less than six interval cancers per 10 000 screens occurring in the first 12 months. However, no age range or standardisation is specified, and confidence intervals are not considered. Another consideration in setting performance standards for mammographic screening services is the difference in results from experimental and operational studies. Randomised trials and other specially constructed studies usually attract significant financial resources and interested investigators. It may be more reasonable to derive standards from studies of operational mammographic screening services whose data, when sufficient studies have been reported, could be assessed to determine performance standards which could reasonably be expected. However, until operational mammography screening services have been shown to produce reduced breast cancer mortality in the screened populations, the results of successful trials must set the gold standard. Acknowledgements The Central & Eastern Sydney Service of BreastScreen NSW and BreastScreen Australia is jointly funded by the Commonwealth and the NSW State Governments. The NSW Central Cancer Registry, which is administered by the NSW Cancer Council and funded by the NSW Health Department, provided valuable assistance with data linkage. References Duffy SW, Tabar L, Fagerberg G, et al. Breast screening, prognostic factors and survival -- results from the Swedish two county study. Br J Cancer 1991; 64: 1133-1138. Day NE, Williams DRR, Khaw KT. Breast cancer screening programmes: the development of a monitoring and evaluation system. Br J Cancer 1989; 59: 954-958. Tabar L, Fagerberg G, Day NE, Holmberg L. What is the optimum interval between mammographic screening examinations? An analysis based on the latest results of the Swedish two-county breast cancer screening trial. Br J Cancer 1987; 55: 547-551. Australian Health Ministers' Advisory Council. Breast Cancer Screening Evaluation Committee. Breast cancer screening in Australia: future directions. Australian Institute of Health, Prevention Program Evaluation Series No. 1. Canberra: AGPS, 1990. National Program for the Early Detection of Breast Cancer -- national accreditation requirements: March 1994. Canberra: Commonwealth Department of Human Services and Health, December 1994. Rickard MT, Lee W, Read JW, et al. Breast cancer diagnosis by screening mammography: early results of the Central Sydney Area Health Service Breast X-Ray Program. Med J Aust 1991; 154: 126-131. Fellegi IP, Sunter AB. A theory for record linkage. J Am Statistical Assoc 1969; 64: 1183-1210. Jaro M. Advances in record linkage methodology as applied to matching the 1985 census of Tampa, Florida. J Am Statistical Assoc 1989; 84: 414-420. Jaro M. Automatch. Generalised record linkage system. Silver Spring, Md: Matchware Technologies Inc, USA, 1994. Taylor R, Smith D, Hfyer A, et al. Breast cancer in New South Wales 1972-91. Sydney: NSW Central Cancer Registry and Cancer Epidemiology Research Centre, NSW Cancer Council, September 1994. Coates M, Day P, McCredie M, Taylor R. Cancer in NSW, incidence and mortality 1992. Sydney: NSW Central Cancer Registry and Cancer Epidemiology Research Centre, NSW Cancer Council, 1995. Armitage P, Berry G. Statistical methods in medical research. 3rd ed. Oxford: Scientific Publications, 1994. Lentner C, editor. Geigy scientific tables. Volume 2: Poisson distribution. Basle, Switzerland: Ciba-Geigy, 1982: 152. Peeters PHM, Verbeek ALM, Hendriks JHCL, et al. The occurrence of interval cancers in the Nijmegen screening programme. Br J Cancer 1989; 59: 929-932. Woodman CBJ, Threlfall AG, Boggis CRM, Prior P. Is the three year breast screening interval too long? Occurrence of interval cancers in NHS breast screening programme's north western region. BMJ 1995; 310: 224-226. Rickard MT, Donnellan M. Diagnosis of small sized invasive breast cancer by an Australian mammography screening service: surrogate end points for mortality reduction. Aust N Z J Surg 1998; 68: 426-429. Robinson JI, Crane CEB, King JM, et al. The South Australian Breast X-Ray Service: results from a statewide mammographic screening programme. Br J Cancer 1996; 73: 837-842. Smith D, Oudod V, Supramaniam R, et al. BreastScreen NSW. Statistical Report 1991-1995. Sydney: NSW Cancer Council, 1996. Coates M, McCredie M, Armstrong B. Cancer in NSW, incidence and mortality 1993. Sydney: Cancer Control Information Centre, NSW Cancer Council, 1996. Parkin DM, Muir CS, Whelan SL, et al, eds. Cancer incidence in five continents. Volume VI. World Health Organization (WHO), International Association of Cancer Registries (IACR), International Agency for Research on Cancer (IARC). Lyon: IARC, 1992. (IARC Scientific Publication No. 120.) Field S, Michell M J, Wallis MGW, Wilson ARM. What should be done about interval breast cancers? BMJ 1995; 310: 203-204. (Received 7 Aug 1997, accepted 3 Apr 1998) Authors' details BreastScreen NSW, Central & Eastern Sydney, Sydney, NSW. Mary T Rickard, FRACR, MPH, Director and Radiologist; Mohamed A Fazli, BScEng, ME, Database Manager; Nadima El Hassan, BEc(Hons), Computer Consultant. Department of Public Health and Community Medicine, Faculty of Medicine, University of Sydney, Sydney, NSW. Richard J Taylor, FAFPHM, FRCP, Associate Professor in Public Health. Reprints will not be available from the authors. Correspondence: Dr M T Rickard, BreastScreen NSW, Central & Eastern Sydney, PO Box 1535, Strawberry Hills, NSW 2012. E-mail: MaryATces.bci.org.au - Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au>". <URL: http://www.mja.com.au/>

Mary T Rickard · Richard J Taylor · Mohamed A Fazli

Acupuncture in Australian general practice: practitioner characteristics Gary Easthope, Justin J Beilby, Gerard F Gill and Bruce K Tranter MJA 1998; 169: 197-200 For editorial comment, see Komesaroff See also Acupuncture in Australian general practice: patient characteristics Abstract - Introduction - Methods - Results - Discussion - Acknowledgements - References - Authors' details - - ©MJA1998 Abstract Objectives: To ascertain the extent of the use of acupuncture and the characteristics of general practitioners using acupuncture. Design: Secondary analysis of 1996 Health Insurance Commission data on claims by all non-specialist medical practitioners for Medicare Benefits Schedule items for an attendance where acupuncture was performed by a medical practitioner. Main outcome measures: Use of acupuncture by general practitioners and the practitioners' sex, age, place of primary medical qualification, and the socioeconomic disadvantage index of the practitioners' practice. Results: 15.1% of general practitioners claimed for acupuncture. Acupuncture was more likely to be provided by male practitioners, by those aged 35-54 years, and by practitioners who have an overseas primary medical qualification. The socioeconomic index of the practice did not significantly affect the number of claims for acupuncture. Conclusion: Acupuncture is used by about one in seven general practitioners. Its use is associated with middle-aged practitioners, who presumably have more clinical experience. This level of use by experienced doctors suggests that a critical review of the appropriate role of acupuncture in general practice should be considered. Introduction There is interest among general practitioners (GPs) in therapies that are not part of traditional medical practice: alternative or complementary therapies.1-4 A recent MJA editorial stated that: "If 50% of Australians are using alternative treatments each year, it is essential that doctors recognise this fact and be prepared to discuss such use with their patients in a non-judgemental manner",4 while American physicians are exhorted "to begin now to integrate some aspects of alternative medicine into family practice".5General practitioners are heeding this exhortation; alternative treatments are used by 16% of GPs in Britain6,7 and Canada,8 and by 30% in New Zealand.9,10 In Germany, which has a tradition of incorporating alternative therapies into orthodox medicine, 95% of GPs use them.11 Even doctors who do not use such therapies refer patients to medical and non-medical practitioners, at rates ranging from 41% of doctors in Israel12 to 80% in New Zealand.9,10 Non-medical practitioners report that about 10% of their patients are referred from doctors.13 Acupuncture is frequently reported in studies of GPs' use of alternative therapies overseas.6,9,10-12 Meta-analyses on acupuncture,14 homoeopathy15 and spinal manipulation16 do not provide evidence for their efficacy, apart from acupuncture for adult postoperative and chemotherapy nausea and postoperative dental pain,17 and spinal manipulation for lower-back pain.18 Other explanations for adoption of these therapies by doctors must therefore be sought. The fact that medicine is a profession in which clinical judgement is considered paramount is important. Interviews with doctors using alternative therapies in Queensland found they justified such use on the basis of clinical experience.19 We studied use of acupuncture to examine doctors' use of alternative therapies. The primary reason for selecting acupuncture was that information on use was available from Medicare data; a specific item in the Medicare Benefits Schedule (now, item 173; before 1991, item 980) has been used at any attendance where acupuncture was performed by a medical practitioner since 1984. Other alternative therapies do not attract a rebate or are not clearly specified. Acupuncture is of interest in that its cost to Medicare is calculable. Methods The Health Insurance Commission (HIC) provided data on all acupuncture claims by GPs in Australia in 1996. Information was provided on the GPs' sex, age, HIC classification (Box 1) and whether their primary medical qualification was Australian or not. The postcode of each GP's major practice was also identified. To ensure no individual was identifiable, the postcode data were classified into 62 categories (later consolidated to 12 for presentation) derived from an Australian Bureau of Statistics list which allots each postcode an index of socioeconomic disadvantage (SDI).20 The postcode data are used as a surrogate measure of patient characteristics in relation to socioeconomic disadvantage on the assumption that patients generally visit doctors in their home area. Our data include the total population of GPs, and therefore any differences between categories are substantively significant. A logistic regression model was constructed using SPSS.21 Fifty-eight GPs who could not be classified either as vocationally registered or as non-vocationally registered were excluded from the logistic regression analysis. The HIC also provided data on the number of acupuncture claims made each year since 1984, and further data were extracted from the statistics on general practice provided by Medicare.22 The University of Tasmania Human Research Ethics Committee approved the study. Results Since acupuncture became a Medicare benefit item in 1984, claims have risen from 655 000 in the financial year 1984-85 to 960 000 in 1996-97 (Figure). Medicare reimbursements have increased from $7.7 million to $17.7 million. In 1996, 2997 (15.1%) of the 19 783 GPs in Australia claimed at least once for acupuncture, and 62 (0.3%) had acupuncture as their major claimed therapy (Box 2). However, acupuncture claims constituted only 0.7% of all claims by vocationally registered GPs22 and pertained only to 1.2% of patients. Doctors who provided acupuncture had a higher number of non-acupuncture claims than non-providing doctors (population mean, 5029; acupuncture providers' mean, 6632; non-providers' mean, 4743). Non-vocationally registered GPs were less likely than vocationally registered GPs to claim for acupuncture (odds ratio [OR], 0.5), while acupuncture providers were more likely to be men (OR, 1.7), aged 35-54 years (OR, 1.7) and hold primary medical qualifications from outside Australia (OR, 1.6) (Box 3). There was no significant linear or quadratic association between the odds of providing acupuncture and the SDI of the doctor's major practice. The sex and age differentials persisted, with marginally different odds ratios, when GPs were distinguished by whether they provided acupuncture infrequently (less than 1% of services), frequently (1%-25% of services) or extensively (25%-100% of services). However, for frequent and extensive providers, there was no significant difference in the odds of providing acupuncture between those qualified in Australia and those in another country. Discussion There were 960 000 Medicare claims for acupuncture in the 1996-97 financial year, costing $17.7 million in reimbursements. As the HIC data do not include acupuncture services funded by agencies such as Workers' Compensation and the Department of Veterans' Affairs or services provided in public hospitals, these figures understate the total use of acupuncture in Australia. In 1996, 15.1% of GPs in Australia claimed for acupuncture. The proportion of GPs using acupuncture in Australia is comparable to the proportion of German (15%)11 and New Zealand doctors (18%)9,10 who provide this service, but much higher than in the United Kingdom (3%).6 Acupuncture may be more accessible to patients in Australia than these results suggest because about 70% of GPs work in group practices.22 A survey of general practices in Hobart found that, although only 15% (27) of the GPs provided acupuncture, it was available in 31% (20) of practices.23 Interestingly, British research found that the use of alternative therapies was more likely in single or one-partner practices than in group practices.7 This difference between the United Kingdom and Australia may be a function either of the 10-year gap between surveys or of different payment systems. In the United Kingdom doctors are paid a set capitation fee; in Australia a fee-for-service model operates. Choice of therapy is independent of patient demand in the United Kingdom, whereas in Australia patients can "shop around". In Australia, offering a choice of conventional and alternative treatments in group practices may simply be good marketing, so that patients can select one or the other but the practice will not lose income. Doctors who provided acupuncture had a greater provision of all other medical services. This suggests that acupuncture is associated with a propensity to provide more services and a greater variety of services. Whether this means acupuncture is associated with practices that have a more complex mix of patients or presenting complaints can only be resolved by a detailed study. Men were more likely than women to provide acupuncture, and this was not a function of age (the difference remained at each age category except the eldest). In this, as in other respects, women appear to practise medicine differently from men.24 The greater likelihood of doctors aged 35-54 years providing acupuncture may be a function of experience. These practitioners may have had many patients with complaints that have not responded to conventional treatment. Given this experience, they are able to try other therapies and trust their clinical judgement as to efficacy. Those older than 65 years may have been less willing to try alternative therapies, or may have decided such therapies are not effective. There are a number of possible reasons why GPs qualified outside Australia may be more likely to provide acupuncture. These doctors may have studied acupuncture as part of their initial medical training, they may have practices in immigrant areas with high patient demand for acupuncture, or they may be subject to less peer pressure to conform to orthodox practice. Without a more detailed study no one explanation can be confirmed or disproved. Previous reports on consumers of alternative therapies suggest these therapies are the choice of young (aged 25-35 years), well-educated and financially secure people, particularly women.25 If acupuncture is an index of the use of alternative therapies, it should be provided in areas of least disadvantage (SDI categories 11 and 12). This is not the case: there was no clear difference between SDI categories (the least-disadvantaged areas, 11 and 12, having only seven frequent or extensive providers). One explanation may be that acupuncture is not claimed through Medicare in these areas. A survey of acupuncture-providing practices in Hobart suggests this is likely, as most providers (60%; 26) and practices (85%; 20) were in relatively affluent suburbs.23 Residents of such areas may also be receiving acupuncture from non-medical practitioners. Additionally, acupuncture may not be a reliable index of use of alternative therapies because it is available on Medicare. Low-income patients may try acupuncture in preference to orthodox treatments, such as physiotherapy, that they would have to pay for. Acupuncture services in Australia have risen steadily since 1984, and 2997 GPs are using acupuncture throughout Australia. Given this level of use, a study of the appropriate role of acupuncture in Australian primary care medical practice should be considered. Acknowledgements The researchers wish to thank the Government Employees Medical Research Fund, which provided funds to conduct the research. References Wardwell WI. Alternative medicine in the United States. Soc Sci Med 1994; 38: 1061-1068. Paterson C. Complementary medicine [letter]. Br J Gen Pract 1996; 46: 440. Murray RH, Rubel AJ. Physicians and healers -- unwitting partners in health care. N Engl J Med 1992; 326: 61-64. Shenfield GM, Atkin PA, Kristoffersen SS. Alternative medicine: an expanding health industry [editorial]. Med J Aust 1997; 166: 516-517. Gordon JS. Alternative medicine and the family physician. Am Fam Physician 1996; 54: 2205-2212. Wharton R, Lewith G. Complementary medicine and the general practitioner. BMJ 1986; 292: 1498-1500. Anderson E, Anderson P. General practitioners and alternative medicine. J R Coll Gen Pract 1987; 37: 52-55. Verhoef MJ, Sutherland LR. Alternative medicine and general practitioners. Opinions and behaviour. Can Fam Physician 1995; 41: 1005-1011. Hadley CM. Complementary medicine and the general practitioner: a survey of general practitioners in the Wellington area. N Z Med J 1988; 101: 766-768. Marshall RJ, Gee R, Israel M, et al. The use of alternative therapies by Auckland general practitioners. N Z Med J 1990; 103: 213-215. Himmel W, Schulte M, Kochen MM. Complementary medicine: are patients' expectations being met by their general practitioners? Br J Gen Pract 1993; 43: 232-235. Borkan J, Neher JO, Anson O, Smoker B. Referrals for alternative therapies. J Fam Pract 1994; 39: 545-550. Fulder SJ, Munro RE. Complementary medicine in the United Kingdom: patients, practitioners, and consultations. Lancet 1985; 2: 542-545. ter Riet G, Kleijnen J, Knipschild P. Acupuncture and chronic pain: a criteria-based meta-analysis. J Clin Epidemiol 1990; 43: 1191-1199. Kleijnen J, Knipschild P, ter Riet G. Clinical trials of homoeopathy. BMJ 1991; 302: 316-323. Shekelle PG, Adams AH, Chassin MR, et al. Spinal manipulation for low-back pain. Ann Intern Med 1992; 117: 590-598. Acupuncture. NIH Consensus statement online 1997 November 3-5 [4 February 1998]; 15. In press. Ernst E. Complementary medicine -- doing more good than harm? Br J Gen Pract 1996; 46: 60-61. Eastwood H. General medical practice, alternative medicine and the globalisation of health [doctoral thesis]. Brisbane: University of Queensland, 1997. Castles I, Information paper: 1991 census. Socio-economic indexes for areas. Canberra: AGPS, 1994. (Catalogue no. 2912.0.) SPSSx statistical package for the social sciences [computer program]. Chicago, Ill: SPSS Inc, 1997. Commonwealth Department of Health and Family Services. General practice in Australia: supplementary tables 1997. Canberra: AGPS, 1997. Bombardieri D. Convergence between orthodox and alternative therapies in Hobart, Tasmania [Honours thesis]. Hobart: University of Tasmania, 1997. Britt H, Bhasale A, Miles DA, et al. The sex of the general practitioner: a comparison of characteristics, patients, and medical conditions managed. Med Care 1996; 34: 403-415. MacLennan AH, Wilson DH, Taylor AW. Prevalence and cost of alternative medicine in Australia. Lancet 1996; 347: 569-573. (Received 7 Jan, accepted 17 Apr 1998) Authors' details Department of Sociology and Social Work, University of Tasmania, Hobart, TAS. Gary Easthope, MA, PhD, Associate Professor; Bruce K Tranter, BA, PhD, Lecturer. Department of General Practice, University of Adelaide, SA. Justin J Beilby, MPH, FRACGP, Senior Lecturer. Division of Community and Rural Health, University of Tasmania, Launceston, TAS. Gerard F Gill, MAE, FRACGP, Clinical Senior Lecturer. Reprints will not be available from the authors. Correspondence: Dr G Easthope, Department of Sociology and Social Work, University of Tasmania, GPO Box 252C-17, Hobart, TAS 7001. E-mail: Gary. EasthopeATutas.edu.au - Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au>". <URL: http://www.mja.com.au/>

Gary Easthope · Justin J Beilby · Gerard F Gill · Bruce K Tranter

For Debate The 100-year conflict: salt intake and cardiovascular disease MJA 1998; 169: 174-180 The health effects of dietary salt have long been debated. As early as the beginning of the 20th century, salt restriction was used as a therapeutic measure, first for oedema and then for hypertension, particularly in France.1 Later, in the United States, the benefits of low salt diets for patients with hypertension and renal disease were championed by Allen in the 1920s and 30s and by Kempner in the late 1930s and 40s.1 However, not all investigators were convinced of the value of these diets, and the hazards of overzealous and prolonged salt restriction were also appreciated.1 By the 1960s and 70s, studies linking an increase in blood pressure of indigenous populations with the introduction of salty Western diets persuaded government bodies to recommend reduced salt as part of healthy dietary guidelines. One of the eight Dietary Goals for Australia, announced in 1979 by the then Commonwealth Department of Health, was "Decrease consumption of salt".2 There are, however, many researchers who maintain that there is insufficient evidence of benefit to recommend universal salt restriction. A summary of this controversy, described as "a philosophical clash between the requirements of public health policy and the requirements of good science", appeared in Science last year.3 In the MJA the salt controversy is alive and well. A study by Beard et al published in 1997 showing a low level of conformity with the year 2000 dietary salt target for Australians (<100mmol/day)4 brought an immediate response from Kincaid-Smith, reminding readers of the possible dangers of low salt intake.5 Then, in March 1998, a study by Alderman et al in the Lancet, claiming to have found an inverse association between dietary salt intake and all-cause and cardiovascular disease mortality,6 revived the international controversy, to which the Lancet's letters columns attest.7-10 Here, we present our own salt debate, with three views of the value (or otherwise) of salt restriction as part of a healthy diet. Universal recommendations for sodium intake should be avoided Restriction of salt intake is needed too ameliorate the cardiovascular disease epidemic The salt dilemma: some answers, many questions Link to salt debate references Dr Derek Denton showed unequivocally that increased salt intake causes a substantial rise in blood pressure in chimpanzees.11 Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au>". <URL: http://www.mja.com.au/>