Acute confusional state in the elderly following hip surgery: incidence, risk factors and complications

Objective To determine incidence and risk factors for the development of po stoperative acute confusional state (ACS) in the elderly. Design A prospective cohort study. Setting University hospital. Patients One hundred and five consecutive patients without ACS at baseline who underwent hip surgery because of hip fracture or elective hip replaceme nt. All patients were 60 years or older. Measurements All patients underwent preoperative and daily postoperative ev aluation by a research psychiatrist. Standardized instruments were used for cognitive screening, baseline assessment of depression, screening for alco hol abuse, comorbidity, and functional status. ACS was diagnosed by using t he Confusion Assessment Method (CAM). Additional medical data were taken fr om patients' charts and anaesthetic records. Results Postoperative ACS developed in 23.8% of the study sample, in 40.5% of the hip fracture group and in 14.7% of the hip joint replacement group. The prevalence was highest between postoperative days 2 and 5. Multiple log istic regression analysis demonstrated the following risk factors of ACS, h igher age (OR = 1.14, 95% CI 1.07-1.22). prior cognitive impairment as meas ured by Mini-Mental State Examination (OR = 1.32 for each point less, 95% C I 1.06-1.64), depression (OR = 3.67, 95% CI 1.12-12.02), low educational le vel (OR = 3.59, 95% CI 1.14-11.25), and preoperative abnormal sodium (OR = 4.32, 95% CI 1.01-18.38). Other risk factors showing statistically signific ant differences in the univariate analyses were: living in nursing home, vi sion or hearing impairment, higher comorbidity, regular use of psychotropic drugs before admission, fracture on admission, preoperative leucocytosis. A considerable proportion of patients with ACS showed self-destructive beha viour postoperatively, whereas self-destructive behaviour was not observed among non-delirious patients. Conclusions ACS is common among elderly hip surgery patients. The occurrenc e of ACS is influenced by several predisposing and precipitating factors. F urther knowledge of these risk factors will contribute to the early identif ication of high risk patients and to the development of preventive measures . Copyright (C) 2001 John Wiley & Sons, Ltd.