Are measures of body habitus associated with mortality in cystic fibrosis?

BACKGROUND: Nutrition 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.

METHODS: Using 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.

RESULTS: Of 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.

CONCLUSIONS: Lower 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.