Changes in lean body mass and total body weight are weakly associated with physical functioning in patients with HIV infection

Abstract

Context. For clinicians managing weight loss in patients with HIV, it would be useful to understand how changes in lean body mass (LBM) effect physical functioning, and whether LBM is more strongly related to physical functioning than total body weight (TBW). Objective. To determine the relationship of changes in LBM and changes in total body weight (TBW) to changes in self-reported physical functioning in men and women with HIV infection. Methods. Study design was longitudinal analysis of 1474 patient-intervals (each interval was approximately 6 months long) in 486 persons. Patients were participants in Nutrition for Healthy Living, a cohort study of HIV positive persons in Massachusetts and Rhode Island. The main outcome measure was change in self-reported physical functioning. Results. Of the 1474 intervals, 1165 were contributed by men and 309 by women. The mean CD4 count for the 1474 intervals was 383 cells/μL. In men, 5 kg changes in LBM and TBW were associated with 2.2 (95% confidence interval, 0.9, 3.4, P = 0.001) and 2.6 (95% confidence interval, 1.3, 3.9, P = 0.0002) point changes in physical functioning (on a 100-point scale), respectively, after adjusting for covariates. The relationships of changes in LBM and TBW to changes in physical functioning were linear. In women, there were no significant relationships between changes in LBM or TBW to changes in physical functioning. Conclusions. In this longitudinal analysis of relatively healthy persons with HIV infection, changes in LBM and TBW were significantly related to changes in physical functioning in men, but the magnitude of the relationship was small. In women, changes in LBM and TBW were not related to changes in physical functioning. Our data suggest that it is not necessary to measure body composition (lean and fat compartments) to understand the impact of changes in weight on physical functioning - it is sufficient to follow total body weight.