Venous Thromboembolism Characteristics and Outcomes Among RIETE Patients Tested & Untested for Inherited Thrombophilia.

Inherited thrombophilia (IT) workup is commonly pursued in venous thromboembolism (VTE) patients. Recent American Society of Hematology (ASH) guidelines recommend a selective approach to IT testing, nevertheless, evidence on whether thrombophilia testing can actually improve patient-important outcomes through tailored management is limited. Data from the large prospective RIETE registry was analyzed to compare VTE risk factors, management and outcomes between patients who were tested for IT and untested patients, during anticoagulant treatment and following its discontinuation. Among 103,818 patients enrolled in RIETE, 21,089 (20.3%) were tested for IT, 8,422 (8.1%) tested positive, and 82,729 (79.7%) were not tested. IT testing was more frequent in patients with VTE provoked by minor risk factors, and less common in those with major risk factors like surgery or active cancer. Choices of anticoagulant treatment did not differ based on IT testing results. Untested patients exhibited inferior outcomes across all VTE categories, with higher rates of VTE recurrence, major bleeding, mortality, and notably, cancer-related mortality. After treatment discontinuation, IT-negative patients with surgically provoked VTE showed lower recurrence rates. For immobilization-related VTE as well as in estrogen-related VTE, no significant differences in recurrence rates were observed between IT-negative and IT-positive patients. However IT-negative patients with pregnancy or postpartum-related VTE, had significantly lower recurrence rates. Patients with unprovoked VTE, particularly those testing positive for IT, had high recurrence rates post-treatment. These findings underscore the complex role of IT testing in managing VTE, supporting personalized treatment strategies that consider VTE risk factors and comorbidities.