Comorbidity Trajectories Before and After Hip Fracture in Elderly Patients: A Korean Nationwide Database Cohort Study

Hip fractures in older adults often signal frailty and are associated with poor outcomes, including mortality and disability. Although a high burden of comorbidities is common, little is known about how these conditions evolve before and after the fracture event. Understanding comorbidity trajectories can inform preventive and rehabilitative strategies.

We analyzed data from the Korean National Health Insurance Service-Senior cohort between 2005 and 2016. A total of 8,319 patients aged ≥ 65 years with surgically treated hip fractures were matched 1:2 with 16,638 controls by age, sex, and year. Comorbidity data were extracted from claims using the International Classification of Diseases, Tenth Revision (ICD-10) codes. We evaluated changes in comorbidity prevalence over a 7-year window (3 years pre- and post-fracture). Difference-in-differences (DIDs) analysis using generalized estimating equations was performed to compare temporal trends between groups.

At the time of fracture, the most prevalent comorbidities were hypertension, osteoarthritis, vertebral disease, osteoporosis, and diabetes. Comorbidity burden increased more steeply in hip fracture patients compared to controls, especially after the fracture event. Notable post-fracture increases were observed in osteoporosis (DID ratio: 1.19), dementia (1.17), congestive heart failure (1.09), Parkinson's disease (1.11), and chronic obstructive pulmonary disease (1.04). In contrast, diabetes (0.96), asthma (0.96), and vertebral disease (0.97) showed relative decreases.

Hip fracture signals not only existing multimorbidity but also accelerates its progression, particularly for neurodegenerative and cardiovascular diseases. Integrated care strategies should proactively address chronic disease burden before and after hip fracture.