Improved fracture prediction using different fracture risk assessment tool adjustments in HIV-infected women

Objectives: A fracture risk assessment tool (FRAX) using clinical risk factors (CRFs) alone underestimates fracture risk in HIV-infected men. Our objective was to determine whether accuracy of FRAX would be improved by considering HIV as a cause of secondary osteoporosis, and further improved with addition of dual-energy X-ray absorptiometry parameters in HIV-infected women. Design: Subgroup analysis of Women's Interagency HIV Study. Methods: We included 1148 women (900 HIV-infected and 248 uninfected) over age 40 with data to approximate FRAX CRFs and 10-year observational data for incident fragility fractures; 181 (20%) HIV-infected women had dual-energy X-ray absorptiometry data. Accuracy ofFRAXwas evaluated by the observed/estimated ratios of fracture in four models: CRFs alone;CRFs withHIVincludedas a causeof secondaryosteoporosis;CRFs andfemoral neck bone mineral density (FN BMD); and CRFs, FN BMD and trabecular bone score. Results: FRAX using CRFs were less accurate in HIV-infected than uninfected women for major osteoporotic (observed/estimated ratio: 5.05 vs. 3.26, P<0.001) and hip fractures (observed/estimated ratio: 19.78 vs. 7.94, P<0.001), but improved when HIV was included as a cause of secondary osteoporosis. Among HIV-infected women, FRAX accuracy improved further with addition of FN BMD (observed/estimated ratio: 4.00) for hip fractures, but no further with trabecular bone score. Conclusion: FRAX using CRFs alone underestimated fracture risk more in older HIVinfected women than otherwise similar uninfected women. Accuracy is improved when including HIV as a cause of secondary osteoporosis for both major osteoporotic and hip fractures, whereas addition of FN BMD only improved accuracy for hip fracture.