Postoperative delirium: age and low functional reserve as independent risk factors

Abstract

Study objective: The aim of this study was to determine the incidence of postoperative delirium (POD) and the presence of previous conditions related to its development.

Design: Prospective observational study.

Settings: The study was performed in adult patients (n=221) scheduled for elective surgery and admitted to the postanesthesia care unit (PACU).

Measurements: The presence of POD was assessed by the Nursing Delirium Screening Scale at discharge from the PACU and 24hours after surgery. Descriptive analyses were carried out, and statistical comparisons were performed with Mann-Whitney U, χ(2), or Fisher exact test. Logistic regression analysis was used for evaluation of independent determinants of POD.

Main results: POD was found in 25 patients (11%). Patients who developed POD were older (median age, 69 vs 57years; P<.001); had a higher American Society of Anesthesiologists physical status score (≥3) (60% vs 19%, respectively, had American Society of Anesthesiologists physical status III/IV; P<.001); and showed higher incidences of ischemic heart disease (24% vs 6%; P=.001), chronic kidney disease (20% vs 5%; P=.005), hypertension (80% vs 45%; P=.001), chronic obstructive pulmonary disease (20% vs 6%; P=.009), and low functional reserve (LFR) (24% vs 2%; P<.001). Age (odds ratio, 1.06; 95% confidence interval, 1.02-1.10; P=.003) and LFR (odds ratio, 8.04; 95% confidence interval, 3.95-32.27; P=.003) were considered independent risk factors for POD.

Conclusions: The incidence of POD in the study population (11%) is consistent with that described in the literature (5%-15%). The comorbidities associated with its development were ischemic heart disease, hypertension, chronic kidney disease, LFR, and chronic obstructive pulmonary disease. Age ≥65years and LFR were independent risk factors for POD development.

Keywords: Low functional reserve; Postoperative care; Postoperative delirium; Risk factors for postoperative delirium.