Cognitive and functional competence after anaesthesia in patients aged over 60: controlled trial of general and regional anaesthesia for elective hip or knee replacement.

OBJECTIVE To determine the influence of general or regional anaesthesia on long term mental function in elderly patients. DESIGN Prospective study of patients randomly allocated to receive general or regional anaesthesia. SETTING The patients' homes and a large teaching hospital in Cardiff. SUBJECTS 146 Patients aged 60 and over scheduled for elective hip or knee replacement. MAIN OUTCOME MEASURES Scores achieved in tests of cognitive function and functional competence. RESULTS 72 Patients were allocated to receive general anaesthesia and 74 regional anaesthesia. Anaesthetic technique did not influence the duration of the operation, time to mobilisation postoperatively, requirements for analgesia after the operation, or duration of stay in hospital. Three months after the operation there was an improvement in the score for the recognition component (76 ms, 95% confidence interval 9 to 144) and the response component (82 ms, 5 to 158) of the choice reaction time in the group receiving general anaesthesia compared with the group receiving regional anaesthesia. This was the only significant difference between the two groups in the assessments of cognitive and functional competence. Eleven patients receiving regional anaesthesia and 12 receiving general anaesthesia reported that their memory and concentration were worse than before the operation, but this was not confirmed by testing. CONCLUSION Cognitive and functional competence in elderly patients was not detectably impaired after either general or regional anaesthesia when attention was paid to the known perioperative influences on mental function.