Low to Moderate Risk Non-orthopedic Surgical Patients Do Not Benefit From VTE Chemoprophylaxis

Abstract

This retrospective cohort study analyzes venous thromboembolism (VTE) incidence, morbidity, and mortality amongst postsurgical patients with and without VTE chemoprophylaxis within a quality collaborative. Postoperative thromboprophylaxis was broadly applied, yet was associated with no decrease in VTE, without affecting transfusion or mortality. Predictors of breakthrough VTE development despite evidencebased thromboprophylaxis are identified. Objective: We hypothesized that a high rate of prescription of VTE chemoprophylaxis would be associated with decreased VTE incidence and mortality. Summary Background Data: Recommendations for VTE prevention in surgical patients include chemoprophylaxis based upon preoperative risk stratification. Methods: This retrospective cohort study analyzed VTE incidence, morbidity, and mortality amongst postsurgical patients with and without VTE chemoprophylaxis between April 2013 and September 2017 from 63 hospitals within the Michigan Surgical Quality Collaborative. A VTE risk assessment survey was distributed to providers. Bivariate and multivariate comparisons were made, as well as using propensity score matched cohorts to determine if VTE chemoprophylaxis was associated with decreased VTE events. Hospitals were compared using risk-reliability adjusted VTE prophylaxis and postoperative VTE event rates. Results: Within the registry, 80% of practitioners reported performing formal VTE risk assessment. Amongst 32,856 operations, there were 480 (1.46%) postoperative VTE, and an overall mortality of 609 (1.85%) patients. Using a propensity matched cohort, we found that rates of VTE were similar in those receiving unfractionated heparin or low molecular weight heparin compared to those not receiving chemoprophylaxis (1.22 vs 1.13%, P = 0.57). When stratified further by VTE risk scoring, even the highest risk patients did not have an associated lower VTE rate (3.68 vs 4.22% P = 0.092). Postoperative transfusion (8.28 vs 7.50%, P = 0.057) and mortality (2.00% vs 1.62%, P = 0.064) rates were similar amongst those receiving and those not receiving chemoprophylaxis. No correlation was found between postoperative VTE chemoprophylaxis application and hospital specific risk adjusted postoperative VTE rates. Conclusions: In modern day postsurgical care, VTE remains a significant occurrence, despite wide adoption of VTE risk assessment. Although postoperative VTE chemoprophylaxis was broadly applied, after adjusting for confounders, no reduction in VTE was observed in at-risk surgical patients.

The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Reduction of Venous Thromboembolic Disease in Colorectal Surgery

“…Other retrospective studies such as a retrospective review of patients from the Michigan Surgical Quality Collaborative examining 32,856 patients having non-orthopedic surgery (6067 patients undergoing colectomy) did not show a decrease in postoperative VTE in patients treated with pharmacologic VTE prophylaxis. 59 Ultimately, these results need to be interpreted in the context of the RCTs and Cochrane analysis to determine whether to use pharmacologic VTE prophylaxis in a given patient.…”