The CLUE postsurgery VTE risk instrument for abdominal and pelvic surgery: validation of patient risk factor component

Venous thromboembolism (VTE) remains a major postoperative risk. Systematic reviews have established procedure-specific VTE risk estimates, which form 1 component of the CLUE postsurgery VTE risk instrument. The instrument also incorporates patient-level factors, including age (≥75 years), body mass index (≥35 kg/m2), and prior VTE, to stratify overall risk. However, the patient risk factor component has not been formally validated. Therefore, we conducted the validation using data from the VISION study, a prospective, international cohort of 11 636 patients undergoing major general abdominal, urologic, or gynecologic surgery. Thirty-day postoperative VTE incidence was analyzed using modified Poisson regression. The instrument classified patients into low- (72%), medium- (25%), and high-risk (4%) categories. VTE occurred in 97 patients (0.8%). Compared to the low-risk group, the relative risk of VTE was 1.56 (95% confidence interval [CI], 1.01-2.43) for medium-risk patients and 3.60 (95% CI, 1.90-6.83) for high-risk patients. Among patients who did not receive antithrombotic medication, relative risks increased to 1.91 for medium-risk patients and 5.41 for high-risk patients. The CLUE postsurgery VTE risk instrument, using 3 widely available patient-level factors, accurately classifies patients into substantially different categories of relative VTE risk. This validated patient component complements procedure-specific absolute risk estimates derived from prior systematic reviews. To support evidence-based thromboprophylaxis decisions, the instrument is now available through an interactive online platform (www.cluevte.org).