Predictors of Higher Bone Mineral Density Loss and Use of Depot Medroxyprogesterone Acetate

OBJECTIVE: To identify possible predictive factors of higher bone loss, defined as at least 5%, at the spine or femoral neck, over time in depot medroxyprogesterone acetate (DMPA) users. METHODS: Bone mineral density (BMD) was measured at the lumbar spine and femoral neck every 6 months in 240 white, African-American, and Hispanic women using DMPA. For the purpose of analysis, an arbitrary value of at least 5% BMD loss from the baseline value after 24 months of DMPA use at either the lumbar spine or the femoral neck was considered as higher BMD loss. Logistic regression analysis was then used to examine factors predictive of at least 5% BMD loss at either site. RESULTS: Of the initial 240 DMPA users, 95 completed 24 months of follow-up. Forty-five of the 95 DMPA users (47.4%) had at least 50% BMD loss at the lumbar spine or femoral neck by 24 months. Multivariable logistic regression model showed that at least 5% BMD loss was associated with current smoking (adjusted odds ratio [OR] 3.88, 95% confidence interval [CI] 1.26-11.96), calcium intake (in 100 mg) (OR 0.81, 95% CI 0.65-0.99), and parity (OR 0.49, 95% CI 0.29-0.82). Age, race or ethnicity, previous contraceptive use, and body mass index were not associated with higher BMD loss. CONCLUSION: The risk of higher BMD loss associated with DMPA use may be reduced by quitting smoking and increasing calcium intake. Having had a child is also protective. (Obstet Gynecol 2010;115:35-40)