Northwestern Medicine study suggests postoperative blood clot rate measure is flawed CHICAGO, Oct. 7, 2013 /PRNewswire-USNewswire/ -- A study published today in JAMA by Northwestern Medicine® researchers suggests that a publicly reported outcomes quality measure, meant to reflect a hospital's success in preventing blood clots following a surgery, is fundamentally flawed. The measure, known as PSI-12 VTE, was designed to measure the rates of patients with postoperative venous thromboembolism (VTE), which occurs when a potentially preventable blood clot develops following a patient's surgery. Such blood clots can cause serious or even fatal complications for patients. The study, "Evaluation of Surveillance Bias and the Validity of the Venous Thromboembolism Quality Measure," found the validity of the quality measure questionable because it scores hospitals based on the rates of patients with postoperative venous thromboembolism (VTE or intravenous blood clot) they report, regardless of how proactive their clinicians are in VTE testing and prevention. The authors argue that the measure doesn't accurately reflect the quality of care provided because it contains a surveillance bias where hospitals that are more vigilant in performing VTE testing will likely find more instances of postoperative VTE, resulting in what appears to be a higher rate of blood clots and a worse hospital ranking. "It is very possible that patients are being misled by this measure when they look at publicly available rankings," said Karl Y. Bilimoria, MD, MS, surgical oncologist at Northwestern Memorial Hospital, director of the Surgical Outcomes and Quality Improvement Center at Northwestern University Feinberg School of Medicine and lead author for the study. "Our results indicate that patients who review hospital rankings or quality reports that use this VTE rate measure may actually be guided away from hospitals with higher levels of safety and quality care, toward lower quality hospitals." To assess the impact of the surveillance bias on the validity of using reported VTE rates as a quality measure, researchers compiled performance results from approximately 2,800 hospitals using 2010 Hospital Compare, American Hospital Association, and Medicare claims data for 954,926 surgical patient discharges following major surgery. VTE imaging and VTE event rates were calculated for each hospital. A summary score of characteristics reflecting a hospital that provides a higher quality of care – such as a hospital's number of accreditations, inpatient beds and quality initiatives – was then applied to each hospital in the study.