How to predict fragility fracture beyond 10 years? The OFELY study.

Context: Low bone mineral density (BMD) is a major determinant of fragility fractures (Fx), but its very long-term prediction is poorly documented.

Objective: We analyzed the risk of Fx beyond 10 years in women.

Design: In a longitudinal cohort study (Os des Femmes de Lyon), we studied 867 women aged 40 years and older (mean age 59 ± 10 y) over 20 years.

Main Outcome: We assessed the risk of the first incident Fx according to the baseline BMD obtained by dual-energy X-ray absorptiometry, clinical risk factors, and the Fracture Risk Assessment Tool (FRAX).

Results: During a median (interquartile range) follow-up of 20 years (3), 245 women sustained one or more incident fragility Fx. Women who sustained a first Fx beyond 10 years (Fx 10-20, n = 109) were younger and had lower values of FRAX compared with those in the first 10 years (Fx 0-10, n = 136). After adjustment for age, they still had greater grip strength and BMD. Parental hip Fx was associated with an increased risk of Fx 10-20 but contrasting with Fx 0-10, the risk of Fx 10-20 was not associated with age, previous Fx, and FRAX except in women younger than 70 years. Each SD decrease of BMD at the spine, femoral neck, total hip, and ultradistal radius was associated with an increased risk of Fx 10-20 with adjusted odds ratios [95% confidence interval (CI)] of 1.43 (95% CI 1.12-1.82), 1.39 (95% CI 1.08-1.82), 1.47 (95% CI 1.14-1.89), and 2.00 (95% CI 1.47-2.7). Women with osteoporosis had an increased risk of both Fx 0-10 and Fx 10-20 compared with women with normal BMD, whereas osteopenia was not associated with a higher risk of Fx beyond 10 years.

Conclusions: Low BMD in women is significantly associated with an increased risk of Fx over 20 years. Beyond 10 years, the prediction conferred by baseline BMD was better than that from clinical risk factors.