Seasonality in hip fracture among haemodialysis patients and kidney transplant recipients in South Korea

Aim: The seasonality of hip fracture in haemodialysis (HD) patients and kidney transplant recipients (KTRs) have not been reported. We assessed seasonal variations in hip fractures among patients with end-stage kidney disease who undergo maintenance HD and KTRs. Methods: Using the Korean National Health Insurance System database from January 2012 to December 2017, monthly counts of hip fracture were calculated among HD patients (n = 77 420) and KTRs (n = 8921). The 6-year normalized monthly fraction and seasonal fractions of hip fractures were calculated. A cosinor analysis was performed to determine the seasonality of the monthly incidence of hip fractures. Results: The 6-year average monthly fraction of hip fractures was lowest in June and highest in October in HD patients, and lowest in February and highest in November in KTRs. The 6-year average seasonal fraction among HD patients was lowest in summer and highest in winter, and lowest in summer and highest in autumn among KTRs, but there was no significant difference. The incidence ratio of hip fractures was lowest in June and highest in January in HD patients, and lowest in August and highest in November in KTRs. On cosinor analysis, HD patients showed significant seasonality in hip fracture incidence, with a trough in summer and a peak in winter (p =.031), whereas KTRs did not exhibit a significant trend (p =.44). Conclusion: Hip fractures occurred more frequently in winter and less frequently in summer in patients undergoing HD, whereas KTRs did not show a seasonal trend.