Volume 195 - Issue 7
Long-term outcomes for patients with cystic fibrosis in Australia
Authors: Kevin J Gaskin and Bridget Wilcken
Med J Aust 2011; 195 (7): 370-371. || doi: 10.5694/mja11.11111
Published online: 3 October 2011
Published online: 3 October 2011
Registries have an important role in monitoring outcomes of complex diseases
In the 1950s, a diagnosis of cystic fibrosis (CF) brought with it a high likelihood of dying from lung disease and a low expectation of surviving beyond 10 years of age.1 By 2011, expectations of survival for people living with CF have been transformed; mean age at death now approaches 27 years,2 and over 90% of patients survive beyond 17 years of age.3 Two studies reported in this issue of the Journal provide a broad overview of recent outcomes achieved in the management of Australian patients with CF.2,3 Both of these Australian studies recognised improved survival among people with CF, but reasons for this improvement remain unclear. Many factors probably contribute, including improvements in medical care, such as anti-pseudomonas antibiotics and better chest therapy in general, and the proven benefit of a high-fat diet for maintaining normal growth and nutritional status.4 Improved socioeconomic status may be a factor: a recent analysis of mortality rates among people with CF in the United Kingdom emphasised that lower socioeconomic status (based on two UK government classifications) contributes to higher mortality rates.5 In addition, a fall in the number of early deaths from CF with the advent of newborn screening has been clearly demonstrated.6 Newborn screening was commenced in New South Wales in 1981 and is of particular significance in the Australian setting. Recent data demonstrate a significant survival advantage for a cohort of babies who were diagnosed with CF during the first 3 years of screening compared with a non-screened cohort. Mortality among the non-screened population after 25 years was nearly twice that among the screened population (66% v 32%).7
Unfortunately, the data for the studies reported in this issue2,3 did not allow calculation of the median survival age, which has been the accepted measure for assessing survival of patients with CF.8 However, to give a perspective on the Australian outcome, in a comparable German study that reported a median age of death of 23.7 years, the median age of survival in 2005 was 37.4 years.8 Considering the higher median age of death in the Australian study, the median age of survival could well approach 40 years. This would also compare favourably with data from France and the United States showing median ages of survival of 36.4 years in 2003 and 37.4 years in 2007, respectively.8 Nevertheless, it is likely that we are behind the Canadian achievement of a median age of survival in 2009 of 46.7 years.9
The Australian studies suggest that further research needs to answer two specific questions: Why does the greatest decline in lung function occur during adolescence? Why is there a “gender gap” of significant survival disadvantage among female patients (with the rate of mortality events among girls more than twice the rate among boys2)? Certainly, it would be important to assess adolescent behavioural issues, including compliance; and the described increase in energy expenditure of over 10% in females during adolescence similarly warrants further investigation.10 A 2009 Canadian Cystic Fibrosis Patient Data Registry report9 confirms that a higher proportion of female adolescents with CF are underweight, and the cause remains enigmatic.
The databases used by the Australian investigators — the Australian Cystic Fibrosis Data Registry (ACFDR)3 and the General Record of Incidence of Mortality (GRIM)2 — have provided invaluable outcome data for comparison of Australian clinics and thus have a benchmark function. CF centres can measure their performance and, at least in part, justify the estimated annual government expenditure on care for patients with CF of A$67 million.3 The investigators emphasise the importance of known factors that influence the effectiveness of databases, including clinic compliance and the painstaking entry of confirmed and accurate data that conforms with standards for international databases. They also have concerns about the longevity of the ACFDR, given that it depends on ad-hoc private funding. Shortfalls in funding will necessitate shortcuts in data entry that will inevitably compromise the completeness and value of the project. It is essential that governments and the community ensure the sustainability of clinical registries that can identify and report on the cost-effectiveness of treatment plans in complex diseases such as CF.
Competing interests
No relevant disclosures.
References
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- Reid DW, Blizzard CL, Shugg DM, et al. Changes in cystic fibrosis mortality in Australia, 1979–2005. Med J Aust 2011; 195: 392-395. 0_i1139867
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- Barr HL, Britton J, Smyth AR, Fogarty AW. Association between socioeconomic status, sex, and age at death from cystic fibrosis in England and Wales (1959 to 2008): cross sectional study. BMJ 2011; 343: d4662. 0_i1139873
- Grosse SD, Rosenfeld M, Owen JD, et al. Potential impact of newborn screening for cystic fibrosis on child survival: a systematic review and analysis. J Pediatr 2006; 149: 362-366. 0_i1139875
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- Cystic Fibrosis Canada. Canadian Cystic Fibrosis Patient Data Registry report, 2009. http://www.cysticfibrosis.ca/assets/files/pdf/CPDR_ReportE.pdf (accessed Aug 2011).
- Allen JR, McCauley J, Selby A, et al. Differences in resting energy expenditure between male and female children with cystic fibrosis. J Pediatr 2003; 142: 15-19. 0_i1139884