Quantitative assessment of cross-sectional muscle area, functional status,and muscle strength in men with the acquired immunodeficiency syndrome wasting syndrome

The acquired immunodeficiency syndrome wasting syndrome (AWS) in men is cha racterized by the loss of lean body mass out of proportion to weight. Altho ugh the wasting syndrome has been thought to contribute to reduced function al capacity, the relationships among lean body mass, muscle size, functiona l status, and regional muscle strength have not previously been investigate d in this population. In this study, 24 eugonadal men with the AWS (weight <90% of the ideal body weight or weight loss >10% from preillness maximum) underwent determination of body composition by dual energy x-ray absorptiom etry (DXA), K-40 isotope analysis, urinary creatinine excretion, and quanti tative computed tomographic analysis of cross-sectional muscle areas of the midarm and thigh. Overall exercise functional capacity was evaluated using the 6-min walk test, and performance of upper and lower extremities was de termined with the quantitative muscle function test. Subjects were 37 +/- 1 yr of age and weighed 95.5 +/- 3.0% of ideal body weight, with a body mass index of 21.9 +/- 0.7 kg/m(2) and an average weight loss of 15 +/- 1%. The mean CD4 count among the subjects was 354 +/- 70 cells/mm(3), and viral lo ad was 58,561 +/- 32,205 copies. Sixty-two percent of subjects were receivi ng protease inhibitor therapy. The subjects demonstrated 90% of the expecte d muscle mass by the creatinine height index method. Overall performance st atus on the Karnofsky scale was highly correlated to weight (r = 0.51; P = 0.018; by body mass index), lean body mass (r = 0.46; P = 0.036; by DXA), a nd body cell mass (r = 0.47; P = 0.037; by K-40 isotope analysis). Cross-se ctional muscle area of the upper extremity was the best predictor (P < 0.00 1) of Karnofsky score, accounting for 52% of the variability in a stepwise regression analysis. Upper body muscle strength was most significantly pred icted by lean body mass (by DXA; r(2) = 0.78; P < 0.0001), whereas lower bo dy strength and performance on the 6-min walk test were best predicted by l ower extremity cross-sectional muscle area (r(2) = 0.70; P < 0.0001 and r(2 ) = 0.26; P = 0.030, respectively). These data demonstrate that cross-secti onal muscle area is highly predictive of functional status and muscle stren gth in men with the AWS.