The CLUE Post-Surgery 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 one component of the CLUE Post-Surgery VTE Risk Instrument. The instrument also incorporates patient-level factors-age (≥75 years), BMI (≥35 kg/m²), and prior VTE-to stratify overall risk. However, the patient risk factor component has not been formally validated. We therefore 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 as low (72%), medium (25%), and high (4%) risk factor categories. VTE occurred in 97 patients (0.8%). Compared to the low-risk group, the relative risks of VTE was 1.56 (95% confidence interval, 1.01-2.43) for medium-risk and 3.60 (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 and 5.41 for high-risk patients. The CLUE Post-Surgery VTE Risk Instrument, using three 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.