Low BMD is an Independent Predictor of Fracture and Early Menopause of Mortality in Post-menopausal Women--a 34-year Prospective Study

Objective: Identify risk factors for fragility fractures and mortality in women aged 48.

Study Design: Prospective population-based observational study on 390 white north European women aged 48 at study start. At study start, we measured bone mineral density (BMD) by single-photon absorptiometry (SPA) in the distal forearm, anthropometry by standard equipment and registered menopausal status, health and lifestyle factors. Menopause before age 47 was defined as early menopause. Incident fragility fractures and mortality were recorded until the women reached age 82. Potential risk factors for fragility fracture and mortality were evaluated with Cox's proportional hazard regression analysis. Data are presented as risk ratios (RR) with 95% confidence intervals in brackets.

Main Outcome Measures: Incidence of fragility fractures and mortality.

Results: In the univariate analysis, low BMD and early menopause predicted fractures. In the multivariate analysis, only BMD remained as an independent risk factor with a RR of 1.36 (1.15, 1.62) per standard deviation (SD) decrease in baseline BMD. In the univariate analysis, early menopause and smoking predicted mortality, and remained as independent risk factors in the multivariate analysis with RR 1.62 (1.09, 2.39) for early menopause and 2.16 (1.53, 3,06) for smoking.

Conclusions: Low BMD at age 48 is an independent predictor for fragility fractures. The predictive ability of early menopause is at least partially attributed to other associated risk factors. Early menopause and smoking were found in this study to be independent predictors for mortality.