The utility of the Montreal cognitive assessment (MoCA) in detecting cognitive impairment in surgical populations - A systematic review and meta-analysis

Study objective: To determine the diagnostic accuracy of the Montreal Cognitive Assessment (MoCA) in detecting cognitive impairment (CI) and assess the association of MoCA scores with adverse postoperative outcomes in surgical populations. Design: Systematic review and meta-analysis. Setting: Perioperative setting. Patients: Adults undergoing elective or emergent surgery screened for CI preoperatively using the MoCA. Measurements: The outcomes included the diagnostic accuracy of the MoCA in screening for CI and the pooled prevalence of CI in various surgical populations. CI and its association with adverse events including delirium, hospital length-of-stay (LOS), postoperative complications, discharge destination, and mortality was determined. Main results: Twenty-six studies (5059 patients, 18 non-cardiac studies, 8 cardiac studies) were included. With a MoCA cut-off score of <26, the prevalence of preoperative CI was 48% (95% CI: 41%-54%). The MoCA had 0.87 (95% CI: 0.79-0.93) sensitivity, 0.72 (95% CI: 0.62-0.80) specificity, PPV of 0.74 (95% CI: 0.65-0.81), and NPV of 0.86 (95% CI: 0.77-0.92) when validated against Petersen criteria, the Diagnostic and Statistical Manual of Mental Disorders, or the National Institute on Aging and the Alzheimer's Association criteria to identify CI. Using the MoCA as a screening tool, the LOS was 3.75 (95% CI: -0.03-7.53, P = 0.05, not significant) days longer in the CI group after non-cardiac surgeries and 3.33 (95% CI: 1.24-5.41, P < 0.002) days longer after cardiac surgeries than the non-cognitively impaired group. Conclusions: MoCA had been validated in the surgical population. MoCA with a cut-off score of <26 was shown to have 87% sensitivity and 72% specificity in identifying CI. A positive screen in MoCA was associated with a 3-day longer hospital LOS in cardiac surgery in the CI group than in the non-CI group.