CLINICAL Review # : 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/cm2; P = 0.12; total hip, -0.02 (95% CI, -0.04, 0.00) g/cm2; P = 0.031; femoral neck, -0.04 (95% CI, -0.07, -0.01) g/cm2; P = 0.013; and total body, -0.03 (95% CI, -0.07, 0.01) g/cm2, 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.