Purpose: The incidence of postoperative cognitive dysfunction (POCD) depends on the test battery and calculation method used. The measurements may be performed with a paper and pencil test battery or with a computerized test battery. The objective of this study was to measure the incidence and congruence of POCD by comparing a computerized test battery with a paper and pencil test battery in the same patient population.
Methods: In total, 67 patients were included: 30 consecutive in-patients undergoing surgery under general anesthesia and 37 non-surgical out-patients as control. Patients were tested with a paper and pencil test battery and a computerized test battery on inclusion in the study and 7 days later. Both test batteries covered the cognitive domains: visual attention, visual learning, memory, and speed of processing.
Results: The computerized test battery classified 10.0% (95% CI 3.5-25.6%) of the patients as suffering from POCD whereas the paper and pencil test battery classified 30.0% (95% CI 16.7-47.9%) as suffering (95% CI for difference 3.9-36.5%, P = 0.03). The inter-rater reliability between both test batteries showed moderate agreement (Cohen's kappa of 0.41). All patients identified by use of the computerized test battery were also identified with the paper and pencil test battery. The paper and pencil test battery identified 6 additional cases.
Conclusion: In our study we demonstrated that the incidence of POCD measured with computerized test battery and paper and pencil test battery showed moderate inter-rater reliability. Use of neuropsychological test batteries theoretically covering the same cognitive domains does not automatically lead to the same classification of POCD.