Refracture or death after osteoporotic fracture: five-year competing-risk and multistate trajectories

Secondary fracture prevention is a priority after osteoporotic fracture, but patients remain at substantial risk of both refracture and death. Because death precludes a subsequently observed refracture, treating it as non-informative censoring can overestimate absolute refracture risk. We therefore used competing-risk and multistate methods to characterize the 5-year trajectories of first recorded hospitalized refracture and death after osteoporotic fracture.

We conducted a retrospective secondary analysis of a de-identified public longitudinal dataset comprising 4,782 patients aged ≥50 years who were hospitalized for osteoporotic fracture between 2017 and 2024. Follow-up began at discharge from the index hospitalization, and the primary analysis included patients with a survival time of ≥30 days after discharge. First recorded hospitalized refracture was the target event, and death before refracture was treated as a competing event. Cumulative incidence functions, cause-specific Cox regression, Fine-Gray regression, and Aalen-Johansen estimation were used to quantify event occurrence, assess covariate associations, and estimate four-state occupation probabilities.

Thirty-one patients died within 0-26 days after discharge and were excluded, leaving 4,751 patients in the primary cohort. Among these patients, 258 experienced first recorded hospitalized refracture as the first event, 487 died before recorded refracture, and 4,006 were censored before either event. At 5 years, the cumulative incidence was 8.63% (95% CI, 7.51-9.75%) for recorded hospitalized refracture and 15.57% (95% CI, 14.12-17.03%) for competing death. The corresponding Aalen-Johansen state probabilities were 75.80% for being alive without recorded refracture, 6.76% for being alive after recorded refracture, 15.57% for death without recorded refracture, and 1.88% for death after recorded refracture. Forty-seven patients had an observed refracture-to-death transition within 5 years, and the small event count limited the precision of estimates for this state.

Among patients with a survival time of ≥30 days after discharge following osteoporotic fracture, the 5-year risk of death before recorded refracture exceeded that of first recorded hospitalized refracture. Competing-risk and multistate methods provided complementary estimates of absolute event risks and subsequent clinical trajectories. These findings are conditional on early post-discharge survival and hospitalization-based outcome capture, which may underestimate the overall refracture burden, particularly for vertebral fractures managed outside hospital settings.