Background: An important factor in the pathophysiology of venous thromboembolism is blood stasis, thus, preoperative hospitalization length of stay may be contributory to risk.
Objective: We assessed preoperative hospital length of stay as a risk factor for venous thromboembolism.
Design: We performed a retrospective review of patients who underwent colorectal operations using univariate and multivariable propensity score analyses.
Settings: This study was conducted at a tertiary referral hospital.
Patients: Data on patients was obtained from the American College of Surgeons National Surgical Quality Improvement Program 2005-2011 Participant Use Data Files.
Main outcome measures: Short-term (30-day) postoperative venous thromboembolism was measured.
Results: Our analysis included 242,670 patients undergoing colorectal surgery (mean age, 60 years; 52.9% women); of these, 72,219 (29.9%) were hospitalized preoperatively. The overall rate of venous thromboembolism was 2.07% (1.4% deep vein thrombosis, 0.5% pulmonary embolism, and 0.2% both). On multivariable analysis, the most predictive independent risk factors for venous thromboembolism were return to the operating room (OR, 1.62 (95% CI, 1.44-1.81); p < 0.001) and chronic steroid use (OR, 1.59 (95% CI, 1.41-1.80); p < 0.001); preoperative hospitalization also independently predicted venous thromboembolism (OR, 1.39 (95% CI, 1.28-1.51); p < 0.001), whereas the use of laparoscopy was protective (OR, 0.75 (95% CI, 0.67-0.83); p < 0.001). Propensity score stratification (capped at 7 days, 100 strata, area under the curve = 0.73) indicated that each day of preoperative hospitalization increased the odds of venous thromboembolism (OR, 1.42 (95% CI, 1.32-1.53); p < 0.001). All of the analyses showed a dose-response relationship between preoperative lengths of stay and risk of postoperative venous thromboembolism (p < 0.001). Patients who experienced venous thromboembolism had a higher 30-day mortality rate (3.7% vs 8.9%; p < 0.001).
Limitations: This study has limited potential generalizability and a retrospective design.
Conclusions: Preoperative hospitalization is an independent risk factor for venous thromboembolism and its associated increase in mortality after colorectal surgery, whereas laparoscopy is a strong protective variable. Further research into preoperative screening for highest-risk patients is indicated.