Measurement of post-operative cognitive dysfunction across 62 studies showed marked heterogeneity, with attention (93%) and memory (95%) most frequently assessed, and four distinct definitions used.
Systematic Review (n=62)
There is significant heterogeneity in how post-operative cognitive dysfunction is measured and defined after cardiac surgery, which may impede research progress and comparability across studies.
Post-operative cognitive dysfunction (POCD) is a decline in cognitive function from pre-operative levels, which has been frequently described after cardiac surgery. The purpose of this study was to examine the variability in the measurement and definitions for POCD using the framework of a 1995 Consensus Statement on measurement of POCD. Electronic medical literature databases were searched for the intersection of the search terms 'thoracic surgery' and 'cognition, dementia, and neuropsychological test.' Abstracts were reviewed independently by two reviewers. English articles with >50 participants published since 1995 that performed pre-operative and post-operative psychometric testing in patients undergoing cardiac surgery were reviewed. Data relevant to the measurement and definition of POCD were abstracted and compared with the recommendations of the Consensus Statement. Sixty-two studies of POCD in patients undergoing cardiac surgery were identified. Of these studies, the recommended neuropsychological tests were carried out in less than half of the studies. The cognitive domains measured most frequently were attention (n=56; 93%) and memory (n=57; 95%); motor skills were measured less frequently (n=36; 60%). Additionally, less than half of the studies examined anxiety and depression, performed neurological exam, or accounted for learning. Four definitions of POCD emerged: per cent decline (n=15), standard deviation decline (n=14), factor analysis (n=13), and analysis of performance on individual tests (n=12). There is marked variability in the measurement and definition of POCD. This heterogeneity may impede progress by reducing the ability to compare studies on the causes and treatment of POCD.
Rudolph et al. (Thu,) conducted a systematic review in Post-operative cognitive dysfunction after cardiac surgery (n=62). Measurement and definition of POCD was evaluated on Variability in the measurement and definitions for POCD. Measurement of post-operative cognitive dysfunction across 62 studies showed marked heterogeneity, with attention (93%) and memory (95%) most frequently assessed, and four distinct definitions used.