Operative variables are better predictors of postdischarge infections and unplanned readmissions in vascular surgery patients than patient characteristics

Abstract

Objective: Although postoperative readmissions are frequent in vascular surgery patients, the reasons for these readmissions are not well characterized, and effective approaches to their reduction are unknown. Our aim was to analyze the reasons for vascular surgery readmissions and to report potential areas for focused efforts aimed at readmission reduction.

Methods: The 2012 to 2013 American College of Surgeons National Quality Improvement Program (ACS NSQIP) data set was queried for vascular surgery patients. Multivariable models were developed to analyze risk factors for postdischarge infections, the major drivers of unplanned 30-day readmissions.

Results: We identified 86,403 vascular surgery patients for analysis. Thirty-day readmission occurred in 8827 (10%), of which 8054 (91%) were unplanned. Of the unplanned readmissions, 61% (n = 4951) were related to the index vascular surgery procedure. Infectious complications were the most common reason for a surgery-related readmission (1940 [39%]), with surgical site infection being the most common type of infection related to unplanned readmission. Multivariable analysis showed the top five preoperative risk factors for postdischarge infections were the presence of a preoperative open wound, inpatient operation, obesity, work relative value unit, and insulin-dependent diabetes (but not diabetes managed with oral medications). Cigarette smoking was a weak predictor and came in tenth in the mode (overall C index, 0.657). When operative and postoperative factors were included in the model, total operative time was the strongest predictor of postdischarge infectious complications (odds ratio [OR] 1.2 for each 1-hour increase in operative time), followed by presence of a preoperative open wound (OR, 1.5), inpatient operation (OR, 2), obesity (OR, 1.8), and discharge to rehabilitation facility (OR, 1.7; P < .001 for all). Insulin-dependent diabetes, cigarette smoking, dialysis dependence, and female gender were also predictive, albeit with smaller effects (OR, 1.1-1.3 for all; P < .001). The overall fit of the multivariable model was fair (C statistic, 0.686).

Conclusions: Infectious complications dominate the reasons for unplanned 30-day readmissions in vascular surgery patients. We have identified preoperative, operative, and postoperative risk factors for these infections with the goal of reducing these complications and thus readmissions. Expected patient risk factors, such as diabetes, obesity, renal insufficiency, and cigarette smoking, were less important in predicting infectious complications compared with operative time, presence of a preoperative open wound, and inpatient operation. Our findings suggest that careful operative planning and expeditious operations may be the most effective approaches to reducing infections and thus readmissions in vascular surgery patients.