Body Weight in Chronic Obstructive Pulmonary Disease: The National Institutes of Health Intermittent Positive-Pressure Breathing Trial

TLDR

Body weight predicts diffusing capacity in COPD patients with similar FEV1, indicating that nutritional status independently affects disease progression. The study reviews how body weight relates to pulmonary function and survival in the intermittent positive‑pressure breathing trial. Researchers related body weight, expressed as a percent of ideal body weight, to multiple disease features recorded in the IPPB dataset, thereby examining its impact on COPD outcomes. Higher body weight correlated with better FEV1, greater exercise capacity, higher diffusing capacity, and lower mortality independent of FEV1, whereas lower weight was associated with increased mortality and higher %TLC.

Abstract

This study reviews the relationship between body weight, pulmonary function, and survival in the recent clinical trial of intermittent positive pressure breathing (IPPB). We related body weight, expressed as a percent of the ideal (%IBW), to the numerous other features of the disease recorded in this data set. Body weight was directly related to FEV1 (p = 0.0001), so that all subsequent analyses of body weight had to first consider FEV1. Mortality appeared to be influenced by body weight independent of FEV1. In patients with %FEV1 less than 35, mortality increased with decreasing body weight (p = 0.093), and this relationship was stronger in patients with %FEV1 35 to 47 (p = 0.048) and even stronger in patients with %FEV1 greater than 47 (p = 0.007). After adjusting for FEV1, body weight was a powerful positive correlate with exercise capacity (p = 0.0001). Body weight was also inversely related to %TLC (p = 0.0408) after adjusting for FEV1. Body weight was a powerful predictor of diffusing capacity (p = 0.0001) in patients with the same FEV1 These results support the hypothesis that factors related to nutritional status are an independent influence on the course of COPD.