Relationship between modified Frailty Index and development of delirium after artificial joint replacement in elderly patients

Objective To evaluate the relationship between modified Frailty Index (mFI) and development of delirium after artificial joint replacement in elderly patients. Methods Elderly patients (aged ≥60 yr) who scheduled for elective hip or knee replacement, were enrolled.Preoperative frailty was assessed using the mFI scale.All the patients received surgery under combined spinal-epidural anesthesia.Primary outcome was the incidence of delirium within 5 days after operation, and delirium was assessed by Confusion Assessment Method or Confusion Assessment Method-Intensive Care Unit.The patients were divided into delirium group and non-delirium group according to whether delirium occurred or not. Results A total of 620 patients were included in the study, the mFI was 0.09 (0.18), and the incidence of delirium within 5 days after surgery was 8.5%.The results of multivariate logistic regression analyses showed that increase in age (OR 1.068, 95% CI 1.018-1.120, P=0.007), higher postoperative consumption of morphine (OR 1.089, 95% CI 1.051-1.128, P<0.01) and higher mFI (OR 2.465, 95% CI 1.636-3.714, P<0.01) were the independent risk factors for postoperative delirium. Conclusion Higher mFI is the independent risk factor for delirium after artificial joint replacement in elderly patients. Key words: Arthroplasty, replacement; Aged; Delirium; Modified frailty index