Is postoperative cognitive dysfunction a risk factor for dementia? A cohort follow-up study

BACKGROUND: /st>Postoperative cognitive dysfunction (POCD) is a common complication in elderly patients after major surgery. An association between POCD and the development of dementia has been suspected. In this study, we assessed if POCD was a risk factor for the occurrence of dementia. METHODS: /st>Danish patients enrolled between November 1994 and October 2000 in the two International Studies of Postoperative Cognitive Dysfunction (ISPOCD 1 and 2) were followed until July 1, 2011. Cognitive performance was assessed at three time points: before operation, at 1 week, and 3 months after surgery, using a neuropsychological test battery. The time of (first) occurrence of dementia after surgery was assessed using the National Patient Register and the Psychiatric Central Research Register. Recorded dementia diagnoses (ICD-8 and ICD-10) were: Alzheimer's disease, vascular dementia, frontotemporal dementia, or dementia without specification. The risk of dementia according to POCD was assessed in the Cox regression models. RESULTS: /st>A total of 686 patients with a median age of 67 [inter-quartile range (IQR) 61-74] yr were followed for a median of 11.1 (IQR 5.2-12.6) yr. Only 32 patients developed dementia during follow-up. The hazard ratio (95% CI) for any dementia diagnoses in patients with POCD at 1 week (n=118) and POCD at 3 months (n=57) after surgery compared with those without POCD was 1.16 (0.48-2.78), P=0.74, and 1.50 (0.51-4.44); P=0.47, respectively. CONCLUSIONS: /st>POCD was not significantly associated with registered dementia over a median follow-up of 11 yr.