Overtime work of anesthesiologists is associated with increased delirium in older patients admitted to intensive care unit after noncardiac surgery: a secondary analysis

Background: Overtime work is common in anesthesiologists due to shortage of manpower. Herein, we analyzed if overtime work of anesthesiologists was associated with delirium development in older patients after surgery.

Methods: This was a secondary analysis of the database from a randomized trial. Seven hundred older patients (aged ≥ 65 years) who were admitted to the intensive care unit (ICU) after elective noncardiac surgery were enrolled in the underlying trial. Anesthesiologists who worked continuously for more than 8 h by the end of the surgery were marked as "work overtime". Delirium was assessed with the Confusion Assessment Method for the ICU twice daily during the first 7 postoperative days. The association between overtime work of anesthesiologists and development of postoperative delirium was analyzed with multivariable logistic regression models.

Results: All 700 patients (mean age 74.3 years, 39.6% female) were included in this analysis. Anesthesiologists of 281 patients (40.1%) were marked as "work overtime" at the end of surgery. When compared with patients whose anesthesiologists didn't work overtime, patients whose anesthesiologist worked overtime had a higher incidence of delirium within 7 days (20.3% [57/281] vs. 12.9% [54/419], P = 0.009). After correction for confounding factors, both overtime work (OR 1.87, 95% CI 1.19-2.94, P = 0.007) and prolonged continuous working hours of anesthesiologists (OR 1.08, 95% CI 1.01-1.15, P = 0.020) were associated with an increased risk of postoperative delirium.

Conclusions: Overtime work of anesthesiologists was associated with an increased risk of delirium development in older patients admitted to ICU after major noncardiac surgery.

Trial registration: The underlying trial was registered with Chinese Clinical Trial Registry ( https://www.chictr.org.cn/showproj.html?proj=8734 ; ChiCTR-TRC-10000802; March 18, 2010).