Delirium: An important postoperative complication

IMPORTANCE Major postoperative complications and delirium contribute independently to adverse outcomes and high resource use in patients who undergo major surgery; however, their interrelationship is not well examined. OBJECTIVE To evaluate the association of major postoperative complications and delirium, alone and combined, with adverse outcomes after surgery. DESIGN, SETTING, AND PARTICIPANTS Prospective cohort study in 2 large academic medical centers of 566 patients whowere 70 years or older without recognized dementia or a history of delirium and underwent elective major orthopedic, vascular, or abdominal surgical procedures with a minimum 3-day hospitalization between June 18, 2010, and August8, 2013.Data analysis took place fromDecember13,2013, throughMay 1,2015. MAIN OUTCOMES AND MEASURES Major postoperative complications, defined as life-altering or life-threatening events (Accordion Severity grade 2 or higher),were identified by expert-panel adjudication. Deliriumwas measured daily with the Confusion Assessment Method and a validated medical record review method. The following 4 subgroupswere analyzed: (1) no complications or delirium; (2) complications only; (3) delirium only; and (4) complications and delirium. Adverse outcomes included a length of stay (LOS) of more than 5 days, institutional discharge, and rehospitalization within 30 days of discharge. RESULTS In the 566 participants, the mean (SD) age was 76.7 (5.2) years, 236 (41.7%) were male, and 523 (92.4%) were white. Forty-seven patients (8.3%) developed major complications and 135 (23.9%) developed delirium. Compared with no complications or delirium as the reference group, major complications only contributed to prolonged LOS only (relative risk [RR], 2.8; 95%CI, 1.9-4.0); by contrast, delirium only significantly increased all adverse outcomes, including prolonged LOS (RR, 1.9; 95%CI, 1.4-2.7), institutional discharge (RR, 1.5; 95%CI, 1.3-1.7), and 30-day readmission (RR, 2.3; 95%CI, 1.4-3.7). The subgroup with complications and delirium had the highest rates of all adverse outcomes, including prolonged LOS (RR, 3.4; 95%CI, 2.3-4.8), institutional discharge (RR, 1.8; 95%CI, 1.4-2.5), and 30-day readmission (RR, 3.0; 95%CI, 1.3-6.8). Delirium exerted the highest attributable risk at the population level (5.8%; 95%CI, 4.7-6.8) compared with all other adverse events (prolonged LOS, institutional discharge, or readmission). CONCLUSIONS AND RELEVANCE Major postoperative complications and delirium are separately associated with adverse events and demonstrate a combined effect. Delirium occurs more frequently and has a greater effect at the population level than other major complications.