The Importance of Previous Fracture Site on Osteoporosis Diagnosis and Incident Fractures in Women

Abstract

Previous fracture increases the risk of subsequent fractures regardless of the site of the initial fracture. Fracture risk assessment tools have been developed to guide clinical management; however, no discrimination is made as to the site of the prior fracture. Our objective was to determine which sites of previous nontraumatic fractures are most strongly associated with a diagnosis of osteoporosis, defined by a bone mineral density (BMD) T-score of ≤ -2.5 at the femoral neck, and an incident major osteoporotic fracture. Using administrative health databases, we conducted a retrospective historical cohort study of 39,991 women age 45 years and older who had BMD testing with dual-energy X-ray absorptiometry (DXA). Logistic regression and Cox proportional multivariate models were used to test the association of previous fracture site with risk of osteoporosis and incident fractures. Clinical fractures at the following sites were strongly and independently associated with higher risk of an osteoporotic femoral neck T-score after adjustment for age: hip (odds ratio [OR], 3.58; 95% confidence interval [CI], 3.04-4.21), pelvis (OR, 2.23; 95% CI, 1.66-3.0), spine (OR, 2.16; 95% CI, 1.77-2.62), and humerus (OR, 1.74; 95% CI, 1.49-2.02). Cox proportional hazards models, with adjustment for age and femoral neck BMD, showed the greatest increase in risk for a major osteoporotic fracture for women who had sustained previous fractures of the spine (hazard ratio [HR], 2.08; 95% CI, 1.72-2.53), humerus (HR, 1.70; 95% CI, 1.44-2.01), patella (HR, 1.54; 95% CI, 1.10-2.18), and pelvis (HR, 1.45; 95% CI, 1.04-2.02). In summary, our results confirm that nontraumatic fractures in women are associated with osteoporosis at the femoral neck and that the site of previous fracture impacts on future osteoporotic fracture risk, independent of BMD.