Incidence of different types of subsequent fractures and related mortality in Taiwan

Abstract

Hip fracture is the most common type of fracture to occur within 2 years after an initial fracture. Mortality risk increases when a subsequent fracture occurs. The occurrence of subsequent fracture is significantly higher in patients with hip fractures than others. Prevention of subsequent fracture is of paramount important.

Purpose: Osteoporotic fracture significantly increases risk of subsequent fracture. In this retrospective cohort study, we used the Taiwan National Health Insurance Database (NHIRD) to analyze data on fractures in a group at high risk of osteoporosis. We aimed to distinguish differences in subsequent fracture types and their relationship with mortality.

Methods: We enrolled patients aged ≥ 50 years old who were diagnosed with an initial fracture classified as hip, vertebral, upper end of the humerus, or wrist. Data from 2 years of follow-up were analyzed. Risks of subsequent fracture events and mortality were calculated by Kaplan-Meier estimation and assessed with Cox proportional hazards models.

Results: We included 375,836 patients from the 2011-2015 NHIRD. Patients with initial hip fracture had the highest incidence of subsequent fracture at both 1- and 2-year follow-up (7.0% and 10.9%). Subsequent fractures occurred mainly at the hip. Conversely, other patients had a higher proportion of subsequent vertebral fracture. Patients with subsequent fracture classified as hip, vertebral, and upper end of the humerus had significantly higher cumulative mortality rates than that of patients who had no subsequent fracture, with adjusted hazard ratios of 1.64 (95% CI = 1.57-1.71, p < 0.01), 1.06 (95% CI = 1.00-1.12, p = 0.04), 1.31 (95% CI = 1.17-1.46, p < 0.01), respectively.

Conclusion: Patients who experienced an initial hip fracture are at greatest risk of subsequent fracture, most commonly the hip. Occurrence of subsequent fractures was associated with an increased mortality risk. Thus, there is a need for early intervention following initial hip fractures.

Keywords: Imminent risk of fracture; Incidence; Mortality; National database; Osteoporotic fracture; Subsequent fracture.