Abstract

Background: Diabetes is increasingly common in cystic fibrosis (CF), but little exists describing its influence on mortality. Using national UK data, this study documents diabetes-specific mortality rates, estimates the impact of diabetes on survival, and estimates population attributable fractions.

Methods: This retrospective cohort study identified 8,029 individuals aged 0–65 years from the UK CF Registry (1996–2005). 5,892 patients were included in analyses of mortality rates and 4,234 in analyses of risk factors. We calculated age-adjusted mortality rates using Poisson regression, standardized mortality ratios using the population of England and Wales, and relative risks using proportional hazards modeling.

Findings: During 17,672 person-years of follow-up, 393 subjects died. The age-adjusted mortality rate was 1.8/100 person-years (95% CI 1.6 to 2.0). The age-adjusted mortality rates per 100 person-years were 2.0 (CI 1.8 to 2.4) in women and 1.6 (95% CI 1.4 to 1.9) in males, and 4.2 (95% CI 3.4–5.1) in individuals with diabetes vs 1.5 (95% CI 1.3 to 1.7) in those without diabetes. Independent risk factors for death included diabetes (hazard ratio, 95% confidence interval, 1.31 (1.03 to 1.67), female sex (1.71, 1.36 to 2.14) plus poorer pulmonary function, lower body mass index, B. cepacia infection, absence of S. aureus infection, allergic bronchopulmonary aspergillosis, liver disease, prior organ transplantation, and corticosteroid use.

Interpretation: Individuals with CF die earlier with diabetes, which, if delayed or better treated, might reasonably extend survival, and merits testing.