Clinically relevant cognitive impairment after cardiac surgery: a 6-month follow-up study

Background and purpose: The majority of studies on neuropsychological compl ications after cardiac surgery used the raw variation of selective tests sc ores to define the occurrence of cognitive decline. We prospectively estima ted the frequency of cognitive impairment after cardiac surgery, with a par ticular emphasis on persistent and clinically relevant cognitive decline. P ossible baseline and operative predictors were also evaluated. Methods: An extensive neuropsychological battery was administered to 110 patients (mean age 64.1 +/- 9.4 years; 70.9% males) undergoing cardiac surgery before and 6 months after the operation. After evaluating the variations in the cogni tive performances, two independent neuropsychologists ranked the patients a s unchanged-improved, mildly-moderately deteriorated, or severely deteriora ted, using a global and functionally oriented judgement. The degree of the impairment was determined in relation to its impact on everyday life activi ties. Results: Ten patients (9.1%) were ranked as severely deteriorated, 22 (20%) as mildly-moderately deteriorated, and 78 (70.9%) as unchanged-impro ved, Cognitively impaired patients were older ( p = 0.031), more often fema les (p = 0.005), with a low education level (p = 0.013). At multivariate an alysis, female gender (odds ratio (OR) 6.14, 95% confidence interval (95% C I) 2.16-17.50), baseline use of beta-blockers (OR 4.55, 95% CI 1.30-1.5.92) , and PaO2 at arrival in intensive care unit (OR for 1 mm Hg increment 1.01 2, 95% CI 1.004-1.020) were significant predictors of cognitive impairment of any degree. Positive predictors of severe cognitive impairment were hist ory of hypertension (OR 5.33, 95% CI 1.03-27.64) and PaO2 at arrival intens ive care unit (OR for 1 mm Hg increment 1.020, 95% CI 1.006-1.035), while e ducation was protective (OR per year of increment 0.53, 95% CI 0.31-0.90). Conclusions: A considerable proportion of cardiac surgery patients may unde rgo clinically relevant cognitive impairment. The knowledge of variables in fluencing cognitive outcome is essential for the adoption of preventive mea sures. (C) 2001 Elsevier Science B.V. All rights reserved.