Predictors of body mass index in patients with moderate to severe emphysema.

People with Chronic Obstructive Pulmonary Disease are at risk for low body weight and the subsequent sequelae of cachexia. The goal of this study was to define the relationship between of degree of emphysema as measured by high resolution chest computerized tomography, body mass index and caloric intake. Subjects from San Diego County were recruited to participate in a multi-center randomized clinical trial to test the Feasibility of Retinoids in the Treatment of Emphysema (FORTE). Forty subjects with Chronic Obstructive Pulmonary Disease, participated in a nutrition substudy and were ex-smokers with FEV(1) between 20%-80% predicted. Body mass index was correlated with the degree of emphysema as measured by high resolution chest tomography (CT), r(2) = 0.171 p < 0.01 across the full spectrum of disease severity. Dietary intake averaged over four days using 24-hour recalls was inversely correlated with BMI, r(2) = 0.471, p < 0.001, indicating a higher energy intake in subjects with low BMI. Pulmonary function tests of percent predicated FEV(1) was mildly related to BMI (r(2) = 0.086, p < 0.06). A regression model was developed to define the relationship of BMI and degree of emphysema and calorie per kilogram body weight, which accounted for 60% of the variability, p < 0.001. Low body weight in the COPD is related to the degree of emphysema, not due to decreased caloric intake. Subjects with low body weight have compensated by increasing their caloric intake and are meeting their nutritional needs.