Diagnostic Criteria of Postoperative Cognitive Dysfunction: A Focused Systematic Review

Abstract

Postoperative Cognitive Dysfunction (POCD) is characterized by a deterioration in cognitive performance after surgery and is increasingly addressed in research studies. However, a uniform definition of POCD seems to be lacking, which is a major threat to clinical research in this area. We performed a focused systematic review to determine the current degree of heterogeneity in how POCD is defined across studies and to identify those diagnostic criteria that are used most commonly. The search identified 173 records, of which 30 were included. Neurocognitive testing was most commonly performed shortly before surgery and at 7 days postoperatively. A variety of neurocognitive tests were used to test a range of cognitive domains, including complex attention, language, executive functioning, perceptual-motor function, and learning and memory. The tests that were used most commonly were the Mini-Mental State Examination, the digit span test, the trail making test part A, and the digit symbol substitution test, but consensus on which test result would be considered “positive” for POCD was sparse. The results of this systematic review suggest the lack of a consistent approach towards defining POCD. However, commonalities were identified which may serve as a common denominator for deriving consensus-based diagnostic guidelines for POCD.

Short term cognitive function after sevoflurane anesthesia in patients suspect to obstructive sleep apnea syndrome: an observational study

“…In order to avoid learning effects, tests were presented in two different versions if required. Although the Mini-Mental-Status-Test (MMST) is a robust test to estimate the severity and progression of cognitive impairment [ 4 ], this test is accused of having learning effects in repeated testing settings. Thus, the assessment battery was adapted and the following tests were performed.…”

“…The incidence over different classes of surgery is provided within a range between 8.9 and 46.1% [3]. Though studies tried to define key factors in the development of POCD, its precise pathogenesis and the underlying mechanisms are still unclear [4]. However, the relation of central inflammation and POCD has been approved, while microglia, astrocytes and mast cell dysfunction as well as deficits in neuronal nutrition support contribute to pathological pathways in cognitive decline [5].…”

Predictors of cognitive dysfunction after cardiac surgery: a systematic review

“…Methodological issues of POCD research have been widely reported, however despite recommendations for a standardized approach, 4,10,11 such variability remains. 7 Reducing heterogeneity in future studies will allow more meaningful comparisons between studies and strengthen the conclusions of systematic reviews in this area. Larger multi-site studies with methodological consistency is one way to achieve this.…”

“…2,3 A key challenge in understanding and managing POCD can be attributed to methodological heterogeneity in the definitions of POCD used across studies, the variety of tests used to diagnose POCD, and timing of testing. [4][5][6][7] Furthermore, POCD lacks a formal definition in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) 8 or the International Classification of Diseases (ICD-10). 9 The need for a standardized approach to the assessment of, and the diagnostic criteria associated with POCD, has been widely recognized.…”

“…9 The need for a standardized approach to the assessment of, and the diagnostic criteria associated with POCD, has been widely recognized. 4,7,10 Recently, consensus recommendations have been published, proposing revised nomenclature for cognitive impairment identified in the perioperative period. 11 These include postoperative cognitive decline diagnosed up to 30 days postoperatively (delayed neurocognitive recovery) or 12 months postoperatively [postoperative neurocognitive disorder (POCD)].…”