title: CLINICAL Review # : low body weight mediates the relationship between HIV infection and low bone mineral density: a meta-analysis.
abstract: BACKGROUND
  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.
  
  
  METHODS
  MEDLINE and EMBASE were searched for English language studies published from 1966 to March 2007, and conference abstracts prior to 2007 were hand-searched.
  
  
  METHODS
  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.
  
  
  RESULTS
  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].
  
  
  CONCLUSIONS
  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.
authors.affiliation: Osteoporosis Research Group, Department of Medicine, University of Auckland, Private Bag 92 019, Auckland, New Zealand. m.bolland@auckland.ac.nz
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Bolland
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Grey
authors.forename: Greg D
authors.initials: GD
authors.lastname: Gamble
authors.forename: Ian R
authors.initials: IR
authors.lastname: Reid
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active / Q000009:adverse effects; D001835:Body Weight / Q000502:physiology*; D015519:Bone Density / Q000502:physiology*; D003627:Data Interpretation, Statistical; D005260:Female; D005272:Femur Neck / Q000473:pathology; D015658:HIV Infections / Q000473:pathology*; D006801:Humans; D008297:Male