Bones, fractures, antiretroviral therapy and HIV

Abstract

Although low bone mineral density (BMD) and bone fractures are increased among HIV-infected adults compared with the general population, no studies have yet characterized their causal association or probability of fracture in the context of HIV infection. Using dual energy X-ray absorptiometry (DEXA) BMD values of the left femoral neck, clinical data collected from two US Centers for Disease Control and Prevention-sponsored HIV cohort studies, factors associated with low BMD, and association of low BMD with subsequent incident fracture were analyzed. Using the FRAX® algorithm, rates of any new bone fracture and major osteoporotic fracture per 100 person-years of follow-up, stratified by initial FRAX® score intervals were assessed. Clinical and demographic risk factors for any new fracture were identified. Among 1008 patients contributing 5,032 person-years of follow up, 36.3% had osteopenia and 2.9% had osteoporosis. Ninety-five incident fractures were observed, predominantly rib/sternum, hand, foot and wrist. Low BMD was significantly associated with age, lower nadir CD4, history of fracture, and male-male sex HIV transmission risk. In multivariable analyses, only osteoporosis and increasing age remained associated with incident fracture. In a separate analysis, FRAX® score of [greater than]3% was also independently predictive of new fracture. In this cohort, median FRAX® scores were higher for those who had any subsequent new fracture vs. those who did not. Of the new fractures, 7.1% occurred among persons with FRAX® score [less than]3% (1.39 per 100py) and 15.3% among persons with FRAX® score [greater than or equal to]3% (3.27 per 100py). New major osteoporotic fractures were observed among 1.5% of persons with FRAX® score [less than]3% (0.30 per 100py), and among 4.9% (1.04 per 100py) of persons with FRAX® score [greater than or equal to]3%. In this large convenience sample of relatively young HIV-infected U.S. adults, low baseline BMD and increasing age were strongly associated with elevated risk of incident fracture, highlighting the potential value of DEXA screening in this population. A FRAX® score [greater than or equal to]3%, low baseline BMD, history of prior fracture, and increasing age were significantly associated with elevated risk of new fracture.