Estimates of Geriatric Delirium Frequency in Noncardiac Surgeries and Its Evaluation Across the Years: A Systematic Review and Meta-analysis

Abstract

Objectives: Delirium is an acute neuropsychiatric syndrome associated with poor outcomes. Older adults undergoing surgery have a higher risk of manifesting perioperative delirium, particularly those having associated comorbidities. It remains unclear whether delirium frequency varies across surgical settings and if it has remained stable across the years. We conducted a systematic review to (1) determine the overall frequency of delirium in older people undergoing noncardiac surgery; (2) explore factors explaining the variability of the estimates; and (3) determine the changing of the estimates over the past 2 decades.

Design: Systematic review and meta-analysis. Literature search was performed in MEDLINE, PubMed, ISI Web of Science, EBSCO, ISRCTN registry, ScienceDirect, and Embase in January 2020 for studies published from 1995 to 2020.

Setting: Noncardiac surgical settings.

Participants: Forty-nine studies were included with a total of 26,865 patients screened for delirium.

Methods: We included observational and controlled trials reporting incidence, prevalence, or proportion of delirium in adults aged ≥60 years undergoing any noncardiac surgery requiring hospitalization. Data extracted included sample size, reported delirium frequencies, surgery type, anesthesia type, delirium diagnosis method, length of hospitalization, and year of assessment. (PROSPERO registration no.: CRD42020160045).

Results: We found an overall pooled frequency of preoperative delirium of 17.9% and postoperative delirium (POD) of 23.8%. The POD estimates increased between 1995 and 2020 at an average rate of 3% per year. Pooled estimates of POD were significantly higher in studies not excluding patients with lower cognitive performance before surgery (28% vs 16%) and when general anesthesia was used in comparison to local, spinal, or epidural anesthesia (28% vs 20%).

Conclusions and implications: Type of anesthesia and preoperative cognitive status were significant moderators of delirium frequency. POD in noncardiac surgery has been increasing across the years, suggesting that more resources should be allocated to delirium prevention and management.

Keywords: Delirium; anesthesia; frequency; incidence; noncardiac surgery; old age.