Body mass index associated with lowest mortality in patients with chronic obstructive pulmonary disease

Abstract

Background: The optimal body mass index (BMI) range for a COPD patient might deviate from WHO recommendations to the general population and depend on disease severity. The BODE index considers a score <21 as low and associated with increased mortality risk. A degree of overweight in more severe COPD patients has been associated with better survival.

Aims: Our aim is to identify the BMI range related to the lowest mortality in subjects without COPD and in patients with COPD patients overall and stratified for severity of lung function impairment.

Methods: We recruited individuals from four independent population-based cohorts: the HUNT Study, the Copenhagen City Heart Study (CCHS), the Copenhagen General Population Study (CGPS) and the OLIN Study. COPD was defined as an FEV1/FVC < 0.70 according to GOLD) 2020 criteria in symptomatic subjects with ≥10 smoking pack-years. BMI was calculated as body weight in kilograms divided by height in meters squared. BMI was modeled using restricted cubic splines. Main outcome was all-cause mortality.

Results: In HUNT, we identified 1361 individuals with repeated measurements. The BMI associated with lowest mortality in the group defined by GOLD criteria was 28.9, and 27,9 in the group defined by GLI. For healthy controls the corresponding BMI was 25.9. Similar results were found in the external cohorts.

Conclusions: The BMI value associated with lowest all-cause mortality was higher in COPD compared to the general non-COPD population. These findings were replicated in four independent study cohorts. BMI ranges recommended for healthy individuals should not be extrapolated to individuals with COPD.