Cognitive dysfunction 1-2 years after non-cardiac surgery in the elderly. ISPOCD group. International Study of Post-Operative Cognitive Dysfunction

BACKGROUND: Postoperative cognitive dysfunction (POCD) is a well-recognised complication of cardiac surgery, but evidence of POCD after general surgery has been lacking. We recently showed that POCD was present in 9.9% of elderly patients 3 months after major non-cardiac surgery. The aim of the present study was to investigate whether POCD persists for 1-2 years after operation. METHODS: A total of 336 elderly patients (median age 69 years, range 60-86) was studied after major surgery under general anesthesia. Psychometric testing was performed before surgery and at a median of 7, 98 and 532 days postoperatively using a neuropsychological test battery with 7 subtests. A control group of 47 non-hospitalised volunteers of similar age were tested with the test battery at the same intervals. RESULTS: 1-2 years after surgery, 35 out of 336 patients (10.4%, CI: 7.2-13.7%) had cognitive dysfunction. Three patients had POCD at all three postoperative test sessions (0.9%). From our definition of POCD, there is only a 1:64000 likelihood that a single subject would have POCD at all three test points by chance. Logistic regression analysis identified age, early POCD, and infection within the first three postoperative months as significant risk factors for long-term cognitive dysfunction. Five of 47 normal controls fulfilled the criteria for cognitive dysfunction 1-2 years after initial testing (10.6%, CI: 1.8-19.4%), i.e. a similar incidence of age-related cognitive impairment as among patients. CONCLUSION: POCD is a reversible condition in the majority of cases but may persist in approximately 1% of patients.