The Impact of Functional Dependence and Related Surgical Complications on Postoperative Mortality

Functional dependency is a known determinant of surgical risk. To enhance our understanding of the relationship between dependency and adverse surgical outcomes, we studied how postoperative mortality following a surgical complication was impacted by preoperative functional dependency. We explored a historical cohort of 6,483,387 surgical patients within the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). All patients ≥ 18 years old within the ACS-NSQIP from 2007 to 2017 were included. There were 6,222,611 (96.5%) functionally independent, 176,308 (2.7%) partially dependent, and 47,428 (0.7%) totally dependent patients. Within 30 days postoperatively, 57,652 (0.9%) independent, 15,075 (8.6%) partially dependent, and 10,168 (21.4%) totally dependent patients died. After adjusting for confounders, increasing functional dependency was associated with increased odds of mortality (Partially Dependent OR: 1.72, 99% CI: 1.66 to 1.77; Totally Dependent OR: 2.26, 99% CI: 2.15 to 2.37). Dependency also significantly impacted mortality following a complication; however, independent patients usually experienced much stronger increases in the odds of mortality. There were six complications not associated with increased odds of mortality. Model diagnostics show our model was able to distinguish between patients who did and did not suffer 30-day postoperative mortality nearly 96.7% of the time. Within our cohort, dependent surgical patients had higher rates of comorbidities, complications, and odds of 30-day mortality. Preoperative functional status significantly impacted the level of postoperative mortality following a complication, but independent patients were most affected.