Prevalence of preoperative cognitive impairment in older surgical patients.: A systematic review and meta-analysis.

STUDY OBJECTIVE:Older surgical patients with cognitive impairment are at an increased risk for adverse perioperative outcomes, however the prevalence of preoperative cognitive impairment is not well-established within this population. The purpose of this review is to determine the pooled prevalence of preoperative cognitive impairment in older surgical patients. DESIGN:Systematic review and meta-analysis. SETTING:MEDLINE (Ovid), PubMed (non-MEDLINE records only), Embase, Cochrane Central, Cochrane Database of Systematic Reviews, PsycINFO, and EMCare Nursing for relevant articles from 1946 to April 2021. PATIENTS:Patients aged ≥60 years old undergoing surgery, and preoperative cognitive impairment assessed by validated cognitive assessment tools. INTERVENTIONS:Preoperative assessment. MEASUREMENTS:Primary outcomes were the pooled prevalence of preoperative cognitive impairment in older patients undergoing either elective (cardiac or non-cardiac) or emergency surgery. MAIN RESULTS:Forty-eight studies (n = 42,498) were included. In elective non-cardiac surgeries, the pooled prevalence of unrecognized cognitive impairment was 37.0% (95% confidence interval [CI]: 30.0%, 45.0%) among 27,845 patients and diagnosed cognitive impairment was 18.0% (95% CI: 9.0%, 33.0%) among 11,676 patients. Within the elective non-cardiac surgery category, elective orthopedic surgery was analyzed. In this subcategory, the pooled prevalence of unrecognized cognitive impairment was 37.0% (95% CI: 26.0%, 49.0%) among 1117 patients, and diagnosed cognitive impairment was 17.0% (95% CI: 3.0%, 60.0%) among 6871 patients. In cardiac surgeries, the unrecognized cognitive impairment prevalence across 588 patients was 26.0% (95% CI: 15.0%, 42.0%). In emergency surgeries, the unrecognized cognitive impairment prevalence was 50.0% (95% CI: 35.0%, 65.0%) among 2389 patients. CONCLUSIONS:A substantial number of surgical patients had unrecognized cognitive impairment. In elective non-cardiac and emergency surgeries, the pooled prevalence of unrecognized cognitive impairment was 37.0% and 50.0%. Preoperative cognitive screening warrants more attention for risk assessment and stratification.