Little empirical evidence exists on how a first (index) complication influences the risk of specific subsequent secondary complications. Understanding these risks is important to elucidate clinical pathways of failure to rescue or death after postoperative complication.OBJECTIVE
To understand patterns of secondary complications in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP).DESIGN, SETTING, AND PARTICIPANTS
Matched analysis using a cohort of 890 604 patients undergoing elective inpatient surgery from January 1, 2005, through December 31, 2011, identified in the NSQIP Participant Use Data File. Five index complications were studied: pneumonia, acute myocardial infarction, deep space surgical site infection, bleeding or transfusion event, and acute renal failure. Each patient with an index complication was matched to a control patient based on propensity for the index event and the number of event-free days. Outcomes were compared using conditional logistic regression.MAIN OUTCOMES AND MEASURES
Rates of 30-day secondary complications and 30-day mortality.RESULTS
Five cohorts were developed, each with 1:1 matching to controls, which were well balanced. Index pneumonia (n = 7947) was associated with increased odds of 30-day reintubation (odds ratio [OR], 17.1; 95% CI, 13.8-21.3; P < .001), ventilatory failure (OR, 15.9; 95% CI, 12.8-19.8; P < .001), sepsis (OR, 7.3; 95% CI, 6.2-8.6; P < .001), and shock (OR, 13.0; 95% CI, 10.4-16.2; P < .001). Index acute myocardial infarction was associated with increased rates of secondary bleeding or transfusion events (OR, 4.3; 95% CI, 3.3-5.8; P < .001), pneumonia (OR, 5.1; 95% CI, 2.6-10.2; P < .001), cardiac arrest (OR, 12.0; 95% CI, 7.5-19.2; P < .001), and reintubation (OR, 11.7; 95% CI, 8.4-16.3; P < .001). Deep space surgical site infection was associated with dehiscence (OR, 30.4; 95% CI, 19.9-46.5; P < .001), sepsis (OR, 13.1; 95% CI, 10.2-16.7; P < .001), shock (OR, 10.6; 95% CI, 6.4-17.7; P < .001), kidney injury (OR, 8.6; 95% CI, 3.9-18.8; P < .001), and acute renal failure (OR, 10.5; 95% CI, 3.8-29.3; P < .001). Index acute renal failure was associated with increased odds of cardiac arrest (OR, 25.3; 95% CI, 9.3-68.6; P < .001), reintubation (OR, 11.3; 95% CI, 7.4-17.1; P < .001), ventilatory failure (OR, 12.4; 95% CI, 8.2-18.8; P < .001), bleeding or transfusion events (OR, 11.3; 95% CI, 6.3-20.5; P < .001), and shock (OR, 11.2; 95% CI, 7.2-17.3; P < .001).CONCLUSIONS AND RELEVANCE
This investigation quantified the effect of index complications on patient risk of specific secondary complications. The defined pathways merit investigation as unique targets for quality improvement and benchmarking.