Association of postoperative delirium with cognitive outcomes: A meta-analysis.

Abstract

STUDY OBJECTIVE\nTo determine the association between postoperative delirium (POD) and cognitive outcomes at least 1\xa0month after surgery in elderly patients, and synthesize the dynamic risk trajectory of cognition impairment after POD.\n\n\nDESIGN\nMeta-analysis searching PubMed, Cochrane and EMBASE from inception to November 1, 2020. The terms postoperative delirium, delirium after surgery, postsurgical delirium, postoperative cogniti*, postoperative cognitive dysfunction, postoperative cognition decline, cognitive decline, cognitive impair* and dement* were searched alone or in combination.\n\n\nMEASUREMENTS\nInclusion criteria were prospective cohort studies investigating the association between POD and cognitive outcomes in patients aged ≥60\xa0years underwent surgery. The primary outcome was the association between POD and cognitive outcomes at 1 or more months after surgery. We considered cognitive outcomes measured up to 12\xa0months after surgery as short-term and beyond 12\xa0months as long-term. Two authors performed the study screening, data extraction and quality assessments. Effect sizes were calculated as Hedges g or Odds ratio (OR) based on random- and fixed-effects models. Meta-regression was conducted to analyze the role of potential contributors to heterogeneity.\n\n\nMAIN RESULTS\nEighteen studies were included. Our result showed a significant and medium association between POD and cognitive outcomes after at least 1\xa0month postoperatively (g\xa0=\xa00.61 95% CI 0.43-0.79; I2\xa0=\xa065.1%), indicating that patients with POD were associated with worse cognitive outcomes. The association of POD with short- and long-term cognitive impairment were also both significant (short-term: g\xa0=\xa00.46 95% CI 0.24-0.68; I2\xa0=\xa053.1%; and long-term: g\xa0=\xa00.82 95% CI 0.57-1.06; I2\xa0=\xa057.1%). A multivariate meta-regression suggested that age and measure of delirium were significant sources of heterogeneity. POD was also associated with the significant risk for dementia (OR\xa0=\xa06.08 95% CI 3.80-9.72; I2\xa0=\xa00) as well as attention (OR\xa0=\xa01.74 95% CI 1.13-2.68; I2\xa0=\xa00), executive (OR\xa0=\xa01.33 95% CI 1.00-1.80; I2\xa0=\xa00) and memory impairment (OR\xa0=\xa01.59 95% CI 1.20-2.10; I2\xa0=\xa043.0%). Additionally, our results showed that the risk trajectory for cognitive decline associated with POD within five years after surgery revealed exponential growth.\n\n\nCONCLUSIONS\nThis is the first meta-analysis quantifying the association between POD and cognitive outcomes. Our results showed that POD was significantly associated with worse cognitive outcomes, including short- and long-term cognitive outcomes following surgery.