Analysis of risk factors for delirium in elderly patients with hip fractures

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Objective To investigate risk factors for postoperative delirium in elderly patients with hip fractures and determine whether the delirium can influence the outcome of hip fracture. Method A retrospective case control study was performed for 521 patients (≥60 years) with hip fractures treated surgically from January 2012 to December 2014.There were 170 males and 351 females, with the age of (79.3±8.3)years. Confusion assessment method (CAM) was applied to diagnose delirium after surgery, and the subjects were divided into delirium group (n=159) and control group (n=362) according to the presence of delirium. Univariate and multivariate analyses were performed to identify the riks factors for postoperative delirium, including age, gender, comorbidities, body mass index, American Society of Anesthesiologists (ASA) classification, type of fracture, haemoglobin, PaO2,albumen, type of anesthesia, type of anesthesia, amount of bleeding, time between admission to surgery, length of operation, type of operation and amount of blood transfusion. Perioperative complications and mortality within 1 year after operation were compared between the two groups. Results Univariate analysis revealed dementia, ASA classification, haemoglobin, PaO2,albumen, interval between admission to surgery, anesthesia method, operation time, and surgery methods were risk factors for postoperative delirium incidence (P<0.05). While multivariate analysis showed only dementia (OR=6.211, 95%CI 2.482-23.498), long interval between admission to surgery (OR=3.505, 95%CI 1.478-6.342), arthroplasty (OR=2.015, 95%CI 1.783-3.481), and PaO2≤60 mmHg (OR=2.766, 95%CI 1.783-5.039) were the significant risk factors for postoperative delirium after hip surgery in the elderly. Incidences of lung infection, wound infection, cardiovascular events, cerebrovascular events and deep venous thrombosis in delirium group were higher than those in control group, but only incidences of lung infection and wound infection reached significant differences (P<0.05). Mortality in delirium group was higher than that in control group within 1 year after operation, but there was significant difference only within 3 months after operation (P<0.05). Conclusions Incidence of delirium is high after hip fracture surgery in the elderly. Dementia, long interval between admission to surgery, arthroplasty and PaO2≤60 mmHg are significant risk factors for postoperative delirium incidence, and the delirium patients are associated with high early mortality. Key words: Hip fractures; Delirium; Aged