Incidence and risk factors of subsequent osteoporotic fracture: a nationwide cohort study in South Korea

Summary: This study analyzed the incidence and risk factors of subsequent osteoporotic fractures in South Korea. The results showed that the incidence rate of subsequent fractures within 24 months was 10.23 per 100 person-years. Additionally, the index hip fracture site was a significant risk factor for a subsequent fracture. Purpose: To identify and analyze the incidence and risk factors of subsequent osteoporotic fractures in South Korea. Methods: This retrospective cohort study analyzed data from the National Health Insurance Review and Assessment claims database from 2012 to 2017. Men and women with osteoporosis, aged ≥50 years, with index fractures between July 1, 2014, and July 1, 2015, were included. The incidence rate of subsequent fractures was calculated by determining the number of second event within 2 years from the index fracture. To identify the risk factors for subsequent fractures, we applied the Cox proportional hazard model to estimate the hazard ratios (HRs). Results: Of the 73,717 patients with osteoporotic fractures, 13,203 (17.91%) had a subsequent fracture. The incidence rate of subsequent fractures within 24 months was 10.23/100 person-years. The index fracture site was a significant risk factor for a subsequent fracture, with the hip showing the highest risk (HR, 7.51; 95% confidence interval [CI], 6.77–8.34), followed by the vertebra (HR, 1.99; 95% CI, 1.91–2.06). The risk of subsequent fractures increased with a higher Charlson Comorbidity Index (CCI) score (CCI score ≥ 5: HR, 1.79; 95% CI, 1.67–1.92). Conclusion: The incidence rate of subsequent osteoporotic fractures in South Korea is similar or higher than that reported in the USA and Europe. A hip fracture within the prior 2 years, relative to other fracture sites, significantly increased the risk of subsequent fractures in osteoporosis patients. Patients who have these risk factors need closer disease management to prevent subsequent fractures.