Are Measures of Body Habitus Associated With Mortality in Cystic Fibrosis?

BackgroundNutrition is an important component of clinical care for patients with cystic fibrosis. We aimed to test the hypothesis that increased BMI, height, and level of creatinine as a biomarker for lean muscle mass are associated with lower mortality and whether differences in these measures may contribute toward sex differences in survival in cystic fibrosis.MethodsUsing a cohort study design, we analyzed data from the UK Cystic Fibrosis Registry for patients who attended an annual assessment visit in 2007 and were followed-up until July 2009.ResultsOf 1,517 individuals, 62 died during the follow-up period. The odds of death were higher among patients in the lowest quintile of serum creatinine compared with the rest of the study population (OR, 3.28; 95% CI, 1.79–5.98). Increased height and higher BMI were also associated with lower risk of death. The higher mortality in female patients (OR, 1.48; 95% CI, 0.93–2.34) was reversed by adjustment using the absolute values for height, BMI, and serum creatinine level (adjusted OR, 0.44; 95% CI, 0.21–0.90) but not by the use of sex-specific values for these exposure variables.ConclusionsLower muscle mass, shorter stature, and a low BMI are associated with increased mortality in cystic fibrosis. These measures of body habitus may contribute to the sex-specific survival differences in individuals with cystic fibrosis.