Estimated impact of model-guided venous thromboembolism prophylaxis versus real-world practice

The American Society of Hematology (ASH) recommends assessing venous thromboembolism (VTE) and major bleeding risk to optimize pharmacological VTE prophylaxis for medical inpatients. However, the clinical utility of model-guided approaches remains unknown.

Our objective was to estimate differences in VTE and major bleeding rates and efficiency with prophylaxis guided by risk models versus clinician judgment. Patients were adults admitted to one of 10 Cleveland Clinic hospitals between December 2017 and January 2020. We compared real-world practice with hypothetical prophylaxis recommended by model-based strategies, including widely used risk scores (Padua & IMPROVE) and locally derived Cleveland Clinic risk prediction models. For each strategy, we quantified the prophylaxis rate, VTE and major bleeding rates, and the incremental number-needed-to-treat (NNT) to prevent one event (VTE or bleeding).

Clinicians prescribed prophylaxis to 62% of patients whereas model-based strategies recommended prophylaxis for 17%-87%. Model-guided prophylaxis produced more VTEs and fewer major bleeds than real-world practice, but total events varied among strategies. Overall, per 1000 patients, model-based strategies produced 14.0-16.1 events compared with 14.3 for real-world practice. The Padua & IMPROVE strategy minimized prophylaxis but caused the most total events. The most efficient model-based strategy recommended prophylaxis to 28% of patients with an incremental NNT (relative to no prophylaxis) of 80. Compared to real-world practice, it reduced prophylaxis by 55% and total events by 0.14%.

Clinicians often prescribed inappropriate prophylaxis, highlighting the need for decision support. Model-guided prophylaxis maximized efficiency by reducing prophylaxis relative to real-world practice without increasing event rates.