Importance
Major postoperative complications and delirium contribute independently to adverse outcomes and high resource utilization in patients undergoing major surgery; however, their inter-relationship is not well-examined.
Objective
To evaluate the association of major postoperative complications and delirium, alone and in combination, with adverse outcomes after surgery.
Design
Prospective cohort study.
Setting
Two large academic medical centers.
Participants
Patients without recognized dementia or history of delirium, age 70 and older who underwent elective major orthopedic, vascular, and abdominal surgeries with a minimum 3-day hospitalization.
Main Outcome and Measures
Major postoperative complications, defined as life altering or threatening events (Accordion Severity ≥ grade 2), were identified by expert panel adjudication. Delirium was measured daily with the Confusion Assessment Method and a validated chart review method. Four subgroups were analyzed: (1) no complications, no delirium; (2) complications alone; (3) delirium alone; and (4) both complications and delirium. Adverse outcomes included length of stay (LOS) > 5 days, institutional discharge, and rehospitalization within 30 days of discharge.
Results
Of 566 participants, mean age (±SD) was 76.7± 5.2 years, 42% male and 92% white. Forty-seven (8%) developed major complications, and 135 (24%) developed delirium. When compared to no complications, no delirium as the reference group, major complications alone contributed only to prolonged LOS (RR 2.8, 95% CI 1.9–4.0); by contrast, delirium alone 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 both 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 a 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 strong combined effect. Delirium occurs more frequently, and has greater impact at the population level than other major complications.