Forearm BMD predicts fracture independently of FRAX.

UNLABELLED: The relationship between bone mineral density (BMD) at the forearm and fracture risk was determined in a meta-analysis of primary data from 11 cohort studies of 35,121 men and women. Low forearm BMD was a significant predictor of fracture risk, independently of FRAX®.

INTRODUCTION

The aim of this study was to quantify the relationship between forearm BMD, FRAX and fracture risk and examine the effect of age, sex, time since measurement, and initial BMD value on fracture risk.

METHODS

We studied 35,121 men and women from 11 predominantly population-based cohorts followed for an average of 11.1 years and a total of 388,654 person-years. The association between forearm BMD, FRAX probabilities (calculated without femoral neck BMD), and the risk of fracture was examined using an extension of the Poisson regression model in each cohort by sex and expressed as the gradient of risk (GR; hazard ratio per 1 SD difference in BMD). The different studies were merged using weighted coefficients.

RESULTS

The GR of forearm BMD for major osteoporotic fracture was 1.41 (95% confidence interval [CI] 1.31-1.51) when adjusted for age and time since baseline and was similar in men and women (p > 0.20). GRs decreased significantly with age. When additionally adjusted for FRAX 10-year probability of major osteoporotic fracture, forearm BMD remained a significant, independent predictor for fracture (GR = 1.34, 95% CI 1.26-1.44). A similar GR was noted for hip fracture (GR = 1.48; 95% CI 1.35-1.62) that persisted after adjustment for FRAX (GR = 1.39; 95% CI 1.27-1.52). Adjustments to FRAX probabilities based on forearm BMD varied by age and Z-score.

CONCLUSIONS

Forearm BMD is a risk factor for MOF and hip fracture risk beyond the risk attributable to FRAX. Its validation on an international basis permits its use in case finding with FRAX.