Body composition and mortality in chronic obstructive pulmonary disease

Area of Science:

• Pulmonary Medicine
• Clinical Nutrition
• Gerontology

Background:

• Chronic obstructive pulmonary disease (COPD) patients with lower body weight exhibit higher mortality rates.
• Existing survival studies indicate a paradox where underweight and normal-weight COPD patients face greater mortality than overweight or obese individuals.

Purpose of the Study:

• To investigate the independent contributions of low fat-free mass and low fat mass to mortality risk in COPD.
• To assess the association between specific body composition metrics and overall mortality in a cohort of COPD patients.

Main Methods:

• A cohort of 412 patients with moderate-to-severe COPD (GOLD stages II-IV) was studied.
• Body composition was evaluated using single-frequency bioelectrical impedance, calculating fat-free mass index and fat mass index.
• Patients were categorized by tissue-depletion patterns, and mortality was tracked over a 5-year follow-up period.

Main Results:

• Forty-six percent of the COPD patients died during the follow-up period.
• Fat-free mass index emerged as an independent predictor of survival (RR: 0.90; 95% CI: 0.84, 0.96; P = 0.003), even after adjusting for disease severity.
• Fat mass index did not show a significant association with mortality; cachexia and muscle atrophy prevalence did not significantly differ between survival groups.

Conclusions:

• Reduced fat-free mass is a significant, independent predictor of mortality in COPD patients, regardless of their fat mass.
• Body composition analysis, particularly fat-free mass, should be considered a systemic marker for assessing COPD disease severity and prognosis.