Adams, Annette L.

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 BMD and FRAX. Our source population from a large healthcare system comprised of 341364 patients (≥65 yr) with an abdominal-pelvic CT during care. Using data from 3035 patients (1790 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, FN volume, hip width, and posterior fat thickness. In a geographically distinct set of 2124 patients (1293 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 5 yr. For the women, the c-statistic for predicting fracture was higher for BCT (0.89, 95% CI: 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, 2-yr 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.

Abstract Randomized trials have not been performed, and may never be, to determine if osteoporosis treatment prevents hip fracture in men. Addressing that evidence gap, we analyzed data from an observational study of new hip fractures in a large integrated healthcare system to compare the reduction in hip fractures associated with standard-of-care osteoporosis treatment in men versus women. Sampling from 271,389 patients aged ≥ 65 who had a hip-containing CT scan during care between 2005 and 2018, we selected all who subsequently had a first hip fracture (cases) after the CT scan (start of observation) and a sex-matched equal number of randomly selected patients. From those, we analyzed all who tested positive for osteoporosis (DXA-equivalent hip BMD T-score ≤ −2.5, measured from the CT scan using VirtuOst). We defined “treated” as at least six months of any osteoporosis medication by prescription fill data during follow-up; “not-treated” was no prescription fill. Sex-specific odds ratios of hip fracture for treated vs not-treated patients were calculated by logistic regression; adjustments included age, BMD T-score, BMD-treatment interaction, BMD, race/ethnicity, and seven baseline clinical risk factors. At two-year follow-up, 33.9% of the women (750/2,211 patients) and 24.0% of the men (175/728 patients) were treated primarily with alendronate; 51.3% and 66.3%, respectively, were not-treated; and 721 and 269, respectively, had a first hip fracture since the CT scan. Odds ratio of hip fracture for treated vs not-treated was 0.26 (95% confidence interval: 0.21–0.33) for women and 0.21 (0.13–0.34) for men; the ratio of these odds ratios (men:women) was 0.81 (0.47–1.37), indicating no significant sex effect. Various sensitivity and stratified analyses confirmed these trends, including results at five-year follow-up. Given these results and considering the relevant literature, we conclude that osteoporosis treatment prevents hip fracture similarly in both sexes.