No one questions the importance of prophylaxis against deep venous thrombosis and pulmonary embolism (collectively known as venous thrombembolsim or VTE) in patients at high risk for such occurrences. But we’ve done several columns that have called into question the use of the VTE prophylaxis measure as a measure of quality because of biases and other flaws.
In our November 2013 What’s New in the Patient Safety World column “Are VTE Measures Flawed as Quality Measures?” we highlighted a study () that looked at almost a million surgical patients in almost 3000 hospitals for VTE prophylaxis rates, VTE event rates, and use of imaging in VTE screening. They found that greater hospital VTE prophylaxis adherence rates were weakly associated with worse risk-adjusted VTE event rates. When they looked at hospitals with higher “structural” quality scores (based on 8 factors commonly thought to be associated with higher commitment to quality) they found higher VTE prophylaxis adherence rates but worse risk-adjusted VTE rates. Risk-adjusted VTE rates increased significantly with VTE imaging use rates in a stepwise fashion, leading to their conclusion that surveillance bias limits the usefulness of the VTE quality measure for hospitals.
In our February 15, 2011 Patient Safety Tip of the Week “Controversies in VTE Prophylaxis” we highlighted a study by some very respected investigators in the surgical quality improvement field (Qadan 2011) that questioned the current recommendations on venous thrombembolism (VTE) prophylaxis in elective major surgery. The authors collected data on DVT and PE in patients electively undergoing 4 major surgical procedures (colorectal resection, total knee replacement, total hip replacement, and hysterectomy) from a large database from a consortium of academic medical centers for two periods of time (2003-2004 vs. 2007-2008). The study demonstrated a substantial increase in the use of pharmacologic DVT prophylaxis between the two time periods. Yet the rates of DVT and PE were not significantly impacted by this increased use of such prophylaxis. Moreover, the overall rates of DVT and PE were actually quite low and the rates in patients who did not receive pharmacoprophylaxis actually decreased between the two time periods. The authors concluded that this may show that clinical judgment of physicians in choosing which patients need pharmacoprophylaxis is remarkable.
Now another study has questioned the utility of the VTE prophylaxis measure (JohnBull 2014). The authors used publicly reported data from CMS to see if there was a correlation between VTE prophylaxis rates and outcome rates and found no correlation. They found that VTE rates at hospitals reporting 100% compliance with VTE prophylaxis were no different than those at hospitals in the bottom quintile of prophylaxis rates. Though the authors note that meeting the minimal standards to comply with the SCIP VTE measure may play a role, they concur with the previous authors also that surveillance bias may be a contributing factor.
Has the time finally come to move on from the VTE prophylaxis process measures to other measures that are less subject to biases and are better matched with actual patient outcomes?
Bilimoria KY, Chung J, Ju MH, et al. Evaluation of Surveillance Bias and the Validity of the Venous Thromboembolism Quality Measure. JAMA 2013; 310(14): 1482-1489
Qadan M, Polk HC, Hohmann SF, Fry DE. A reassessment of needs and practice patterns in pharmacologic prophylaxis of venous thromboembolism following elective major surgery. Ann Surg 2011; 253(2): 215-220
JohnBull EA, Lau BD, Schneider EB, et al. No Association Between Hospital-Reported Perioperative Venous Thromboembolism Prophylaxis and Outcome Rates in Publicly Reported Data (Research Letter). JAMA Surgery 2014; online first February 5, 2014
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