Improved Prediction of Hip Fracture Using Multi-Faceted Biomechanical Computed Tomography.

Abstract

With the goal of preventing more hip fractures, a next generation of the VirtuOst® Biomechanical Computed Tomography (BCT) test was developed that integrates measurements from a clinical CT scan related to fall risk, impact force, and femoral strength, the three main determinants of hip fracture. Here, we introduce the test and validate it against bone mineral density (BMD) and FRAX®. Our source population from a large healthcare system comprised of 341,364 patients (≥ 65 years) with an abdominal-pelvic CT during care. Using data from 3,035 patients (1,790 with hip fracture), we developed a "BCT Risk Score" (range: 0-100) having input risk factors of age, femoral strength, ratio of trabecular/cortical BMD, muscle area, intramuscular fat, femoral neck volume, hip width, and posterior fat thickness. In a geographically distinct set of 2,124 patients (1,293 with hip fracture), we then compared the BCT Risk Score against a DXA-equivalent hip BMD T-score (lowest hip value, measured from the CT scan by VirtuOst) and FRAX hip fracture risk (with BMD but without parental fracture history) for predicting a first incident hip fracture within five years. For the women, the c-statistic for predicting fracture was higher for BCT (0.89, 95% confidence interval 0.87-0.90) than for BMD (0.81, 0.79-0.84) or FRAX (0.85, 0.83-0.87). Using binary thresholds to identify high-risk patients, sensitivity for BCT (Risk Score ≥ 75) was higher than for BMD (T-score ≤ -2.5) and FRAX (hip risk ≥ 3.0%): 81.4% vs. 47.8% vs. 75.9%, respectively; positive predictive values confirmed comparable high-risk status (BCT 13.6% vs. BMD 15.3% vs. FRAX 12.7%). Similar trends were observed for the men, two-year outcomes, and identifying very-high-risk patients. We conclude that, compared to both BMD and FRAX, the integrative BCT test better predicted hip fracture and its high sensitivity should improve fracture prevention.