Low body weight mediates the relationship between HIV infection and low bone mineral density: A meta-analysis

Context: HIV infection has been associated with low bone mineral density ( BMD) in many cross-sectional studies, although longitudinal studies have not demonstrated accelerated bone loss. The cross-sectional studies may have been confounded by the failure to control for low body weight in HIV-infected patients. Objective: Our objective was to determine whether low body weight might explain the association of HIV infection with low BMD. Data Sources: MEDLINE and EMBASE were searched for English language studies published from 1966 to March 2007, and conference abstracts prior to 2007 were hand-searched. Study Selection: All studies reporting BMD and weight or body mass index in adult patients with HIV and a healthy age- and sex-comparable control group were included. Nine of 40 identified studies and one of 68 identified abstracts were eligible. Data Synthesis: We adjusted for the between-groups weight differences using regression coefficients from published cohorts of healthy men and women. On average, HIV-infected patients were 5.1 kg [ 95% confidence interval (CI), -6.8, -3.4; P < 0.001] lighter than controls. At all skeletal sites, unadjusted BMD was lower by 4.4-7.0% in the HIV-infected groups than the controls ( P < 0.01). After adjustment for body weight, residual between-groups differences in BMD were small ( 2.2-4.7%) [lumbar spine, -0.02 ( 95% CI, -0.05, 0.01) g/cm(2); P = 0.12; total hip, -0.02 ( 95% CI, -0.04, 0.00) g/cm(2); P = 0.031; femoral neck, -0.04 ( 95% CI, -0.07, -0.01) g/cm(2); P = 0.013; and total body, -0.03 ( 95% CI, -0.07, 0.01) g/cm(2), P = 0.11]. Conclusion: HIV-infected patients are lighter than controls and low body weight may largely account for the high prevalence of low BMD reported in HIV-infected patients. However, in the setting of current treatment practice, HIV infection per se is not a risk factor for low BMD.