Prediction of Cardiorespiratory Fitness in Older Men Infected with the Human Immunodeficiency Virus: Clinical Factors and Value of the Six-Minute Walk Distance.

OBJECTIVES: To investigate factors related to cardiorespiratory fitness in older human immunodeficiency virus (HIV)-infected patients and to explore the utility of 6-minute walk distance (6-MWD) in measuring fitness. DESIGN: Cross-sectional study in clinic-based cohort. SETTING: Veterans Affairs Medical Center, Baltimore, Maryland. PARTICIPANTS: Forty-three HIV-infected men, median age 57 (range 50–82), without recent acquired immunodeficiency syndrome–related illness and receiving antiretroviral (ARV) therapy. MEASUREMENTS: Peak oxygen utilization (VO2peak) according to treadmill graded exercise testing, 6-MWD, grip strength, quadriceps maximum voluntary isometric contraction, cross-sectional area, muscle quality, and muscle adiposity. RESULTS: There was a moderate correlation between VO2peak (mean ± SD; 18.4 ± 5.6 mL/kg per minute) and 6-MWD (514 ± 91 m) ( r=0.60, P<.001). VO2peak was lower in subjects with hypertension (16%, P<.01) and moderate anemia (hemoglobin 10–13 gm/dL; 15%, P=.09) than in subjects without these conditions. CD4 cell count (median 356 cells/mL, range 20–1,401) and HIV-1 viral load (84% nondetectable) were not related to VO2peak. Among muscle parameters, only grip strength was an independent predictor of VO2peak. Estimation of VO2peak using linear regression, including age, 6-MWD, grip strength, and hypertension as independent variables, explained 61% of the variance in VO2peak. CONCLUSION: Non-AIDS-related comorbidity predicts cardiorespiratory fitness in older HIV-infected men receiving ARV therapy. The 6-MWD is a valuable measure of fitness in this patient population, but a larger study with diverse subjects is needed. [ABSTRACT FROM AUTHOR]