Methodology of measuring postoperative cognitive dysfunction: a systematic review

Abstract

Background: Postoperative cognitive dysfunction (POCD) is an adverse outcome that impacts patients' quality of life. Its diagnosis relies on formal cognitive testing performed before and after surgery. The substantial heterogeneity in methodology limits comparability and meta-analysis of studies. This systematic review critically appraises the methodology of studies on POCD published since the 1995 Consensus Statement and aims to provide guidance to future authors by providing recommendations that may improve comparability between future studies. Methods: This systematic review of literature published between 1995 and 2019 included studies that used baseline cognitive testing and a structured cognitive test battery, and had a minimal follow-up of 1 month. For cohorts with multiple publications, data from the primary publication were supplemented with available data from later follow-up studies. Results: A total of 274 unique studies were included in the analysis. In the included studies, 259 different cognitive tests were used. Studies varied considerably in timing of assessment, follow-up duration, definition of POCD, and use of control groups. Of the 274 included studies, 70 reported POCD as a dichotomous outcome at 1 to <3 months, with a pooled incidence of 2998/10 335 patients (29.0%). Conclusions: We found an overwhelming heterogeneity in methodology used to study POCD since the publication of the 1995 Consensus Statement. Future authors could improve study quality and comparability through optimal timing of assessment, the use of commonly used cognitive tests including the Consensus Statement 'core battery', application of appropriate cut-offs and diagnostic rules, and detailed reporting of the methods used. PROSPERO registry number: CRD42016039293.

Post-Operative Cognitive Impairment: A Cognitive Epidemiology Perspective

“…Post-operative delirium (POD) is characterized by agitation or apathy and affects around 19–28% of patients during the days after surgery ( Ho et al 2021 ); post-operative cognitive dysfunction (POCD) describes a decline in cognitive test performance across surgery that can last weeks to years. At 3 to 6 months, POCD can be detected in around 10–25% of patients ( Borchers et al 2021 ). This article aims to provide a narrative review of the currently limited evidence on the cognitive epidemiology of post-operative cognitive impairment.…”

Effect of Dexmedetomidine on Early Postoperative Cognitive Function in Patients Undergoing Arthroscopic Shoulder Surgery in Beach Chair Position: A Randomized Double-Blind Study

“…Finally, the negative finding may have resulted from the relatively short intervals between the baseline examination and the postoperative examination of the MMSE-K and cognitive battery of tests. The POCD test is usually performed within seven days or before/at discharge from the hospital to abate the acute effects of hospitalization, anesthesia, and surgery [ 28 ]. However, in a previous study by Silbert et al, the authors reported that 30% of patients had neuropsychological changes within 18 h after cardiac surgery [ 29 ].…”

Effects of Glucocorticoids on Postoperative Neurocognitive Disorders in Adult Patients: A Systematic Review and Meta-Analysis

“…The diagnosis of PNDs, especially POCD, is complex requiring neuropsychological tests which are varied in studies. A recent systematic review noted that in 274 existing studies of POCD, diagnosis was based on 259 different cognitive assessment tools (Borchers et al, 2021). Moreover, neuropsychological tests have been undertaken at variable time intervals after anesthesia and surgery.…”