Predicting the Subsequent Contralateral Hip Fracture: Is FRAX the Answer?

OBJECTIVES: To (1) determine the ability of the Fracture Risk Assessment Tool (FRAX) to identify the probability of contralateral hip fractures within 2 years of index fracture and (2) identify independent risk factors for a subsequent hip fracture. DESIGN: Retrospective. SETTING: Urban, academic medical center. PATIENTS: This study included a consecutive series of patients treated for unilateral hip fractures between September 2015 and July 2019. RESULTS: Eight hundred thirty-two consecutive patients were included in the analysis with a mean age of 81.2 ± 9.9 years. Thirty-one (3.7%) patients sustained a contralateral hip fracture within 2 years with these patients sustaining the second fracture at a mean 294.1 days ± 197.7 days. The average FRAX score for the entire cohort was 11.9 ± 7.4, and the area under receiving operating characteristic curve (AUROC) for FRAX score was 0.682 (95% CI, 0.596-0.767). Patients in the high-risk FRAX group had a >7% risk of contralateral hip fracture within 2 years. Independent risk factors for contralateral hip fracture risk included patient age 80 years or older and decreasing BMI. CONCLUSIONS: This study demonstrates the strong ability of the FRAX score to triage patients at risk of subsequent contralateral hip fracture within 2 years. In this high-risk FRAX group, patients age older than 80 years and who have decreasing BMI after their index fracture have a 12.5% increased risk of fracture within 2 years which is 4× higher than the current World Health Organization 10-year 3% hip fracture risk standard used to initiate pharmacologic treatment. Therefore, high-risk patients identified using this methodology should be targeted more aggressively with preventative measures including social, medical, and potentially surgical interventions. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.