Predictive ability of Mini-Cog for postoperative delirium: A systematic review and meta-analysis

This study aims to determine the predictive value of the preoperative Mini-Cognitive Assessment Instrument (Mini-Cog) for postoperative delirium (POD), a significant complication in older surgical patients. Given its widespread recommendation despite unclear predictive utility, we will conduct the first meta-analysis to synthesize the available evidence.

A systematic review and meta-analysis were conducted following PRISMA guidelines. Electronic databases (Medline, CINAHL, Cochrane Library, and Web of Science) were searched from inception to May 2024. Studies evaluating the association between preoperative Mini-Cog scores and POD were included. Two independent reviewers performed study selection and data extraction. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Random-effects models were used to calculate pooled odds ratios (ORs), sensitivity, and specificity. Sensitivity analyses were performed based on standardized cutoff values and POD assessment methods.

Sixteen studies involving 4980 patients were included. Participants' mean/median ages ranged from 70 to 80 years, and the percentage of patients scoring below the Mini-Cog cutoff varied from 12.5% to 60.5%. Low Mini-Cog scores were significantly associated with increased POD risk (OR = 3.79; 95% confidence interval [CI] = 2.81-5.12; I² = 57%). The Mini-Cog demonstrated a pooled specificity of 0.80 and sensitivity of 0.50 for POD prediction. Sensitivity analysis of studies using standardized cutoffs (<3) and validated POD assessment tools yielded an OR of 3.40 (95% CI = 2.56-4.53). Half of the included studies showed a low risk of bias across all QUADAS-2 domains. Publication bias assessment using funnel plots and Egger's test showed no significant bias.

The Mini-Cog shows moderate predictive ability for POD, with high specificity but limited sensitivity. While it may be valuable as part of comprehensive preoperative assessment, its moderate sensitivity suggests it should not be used as the sole predictor. The variability in surgical populations and assessment methods highlights the need for standardization. Future research should focus on establishing consistent methodologies and exploring the Mini-Cog's efficacy in specific surgical populations to enhance its clinical utility in POD risk stratification. Geriatr Gerontol Int 2025; 25: 738-748.