Functional impairment is associated with low bone and muscle mass among persons aging with HIV infection

Abstract

Background: Disability and frailty are associated with osteoporosis, obesity, and sarcopenia. HIV-infected persons have early functional impairment, but the association between body composition and functional impairment is unknown.

Methods: HIV-1-infected participants on combination antiretroviral therapy with virologic suppression, aged 45-65 years, had standardized physical function measures. In a nested analysis, 30 low- and 48 high-functioning cases and controls were matched by age, gender, and time since HIV diagnosis. Bone mineral density, fat mass, and lean body mass were assessed by dual-energy x-ray absorptiometry. Odds ratios (ORs) with 95% confidence intervals were obtained from conditional logistic regression.

Results: Mean age was 53 years, mean CD4(+) lymphocytes 598 cells per microliter, and 96% had plasma HIV-1 RNA <50 copies per milliliter. Low- and high-function subjects had similar CD4(+) lymphocyte count and duration and type of antiretroviral therapy. Lower T scores at the hip [OR: 3.8 (1.1 to 12.5)] and lumbar spine [OR: 2.3 (1.1 to 4.5)] and lower lean body mass [OR: 1.1 (1.0 to 1.2)] were associated with significantly greater odds of low function (P ≤ 0.03). Lower insulin-like growth hormone [IGF-1; OR: 5.0 (1.4 to 20.0)] and IGF-1 binding protein-3 [OR: 3.3 (1.7 to 9.9)] increased the odds of low functional status (P ≤ 0.02). Fat mass and lower 25-OH vitamin D did not increase the odds of low functional status (P > 0.05).

Conclusions: Functional impairment in HIV-1-infected persons on successful antiretroviral therapy is associated with low muscle mass, low bone mineral density, and low IGF-1 and IGF-1 binding protein-3. These characteristics may be a manifestation of early "somatopause" in middle-aged HIV-infected adults.

Figure 1

Proposed relationship between body and bone composition and the development of functional impairment in persons aging with HIV infection. Both age and HIV-1 contribute to low insulin-like growth factor (IGF)-1. Low IGF-1 is associated with central adiposity, low muscle mass, and low bone mineral density, all of which contribute to functional impairment.