Impact of Dementia, Depression, and Other Mental Disorders on Reoperation and Mortality among Hip Fracture Patients: A Nationwide Danish Cohort Study

Abstract Background Despite the rising global burden of mental disorders, their impact on complication risk following hip fracture surgery remains unclear. We examined reoperation and mortality risks after hip fracture surgery, investigating patients with and without moderate to severe mental disorders. Methods Using a nationwide cohort design, we identified patients undergoing hip fracture surgery from the Danish Multidisciplinary Hip Fracture Register. Mental disorders (including organic disorders (dementia), substance use, schizophrenia, mood disorders, and neurotic disorders) and reoperations were determined using diagnosis and procedure codes in the Danish National Patient Registry. We estimated reoperation and mortality risk with adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs), comparing each mental disorder to no mental disorder while accounting for death as a competing risk. Results Among 110,625 hip fracture patients from 2004 to 2021, 15,254 (14%) had a mental disorder. The 30-day aHRs for reoperation ranged from 1.05 (CI: 0.9–1.2) for dementia to 1.67 (CI: 1.3–2.1) for substance use. The 365-day aHRs for reoperation ranged from 0.92 (CI: 0.9–1.0) for dementia to 1.37 (CI: 1.2–1.5) for neurotic disorders. Patients with mental disorders had an increased aHR for mortality at both 30-day and 365-day follow-up compared to patients without mental disorders, with the most pronounced risk observed among patients with dementia. Conclusion The risk of reoperation and mortality following hip fracture surgery was significantly higher in patients with moderate to severe mental disorders compared to those without. These findings emphasise the need for targeted prevention strategies to reduce reoperation risk and mortality.