ABSTRACT
Describing the health of large patient populations is made possible in part through the use of national disease registries. As such, we have made use of the 2011 annual reports from the Cystic Fibrosis Foundation (CFF) in the United States,1 Cystic Fibrosis Trust in the United Kingdom,2 Cystic Fibrosis Canada,3 and 2008-2009 data from the European CF Society.4 We also included 2009 data from Australia published by Bell et al.5 Comparisons between countries, however, should be made cautiously as countries will have dierent health-care systems and treatment practices and registries will dier in the way data are collected (annual reviews or encounter based, for example), levels of completeness, and reference values used for nutritional and pulmonary outcomes. Additionally, it is worth noting that registry studies-like all observational studies-are prone to ascertainment bias where all patients are not represented equally in the cohort. In relation to registry studies, this may stem from national screening practices (or lack thereof) where patients with certain genotypes are less likely to be identied. Registries based on being treated at specialist centers are also at risk of bias if there are groups of patients who are unable to access such services. is may be for reasons of geography or ability to pay, for example. Given this potential for bias, it is important when interpreting results to be mindful of how patients are identied for such registries and their estimated coverage. For example, the 2011 annual report produced by the Cystic Fibrosis Trust in the United Kingdom-where there exists a universal access health-care system and all CF patients are seen at specialist centers-included data on 89% of the patients registered at these centers. Data from Italy, however, which are included
in the European Cystic Fibrosis Society’s report, cover only an estimated 14% of patients.
