Faster lumbar spine bone loss in midlife predicts subsequent fracture independent of starting bone mineral density.

Context Bone mineral density (BMD) decreases rapidly during the menopause transition (MT), and continues to decline in postmenopause. Objective To examine whether faster BMD loss during the combined MT and early postmenopause is associated with incident fracture, independent of starting BMD, before the MT. Design and setting The Study of Women's Health Across the Nation (SWAN), a longitudinal cohort study. Patients or participants 451 women, initially pre- or early perimenopausal, and transitioned to postmenopause. Main outcome measures Time to first fracture after early postmenopause. Results In Cox proportional hazards regression, adjusted for age, body mass index, race/ethnicity, study site, use of vitamin D and calcium supplements, and use of bone--detrimental or beneficial medications, each SD decrement in lumbar spine (LS) BMD before the MT was associated with a 78% increment in fracture hazard (p=0.007). Each 1% per year faster decline in LS BMD was related to a 56% greater fracture hazard (p=0.04). Rate of LS BMD decline predicted future fracture, independent of starting BMD. Women with a starting LS BMD below the sample median, and a LS BMD decline rate faster than the sample median had a 2.7-fold greater fracture hazard (p=0.03). At the FN, neither starting BMD nor rate of BMD decline was associated with fracture. Conclusions At the LS, starting BMD before the MT and rate of decline during the combined MT and early postmenopause are independent risk factors for fracture. Women with below-median starting LS BMD and faster-than-median LS BMD decline have the greatest fracture risk.