Venous thromboembolism characteristics and outcomes among RIETE patients tested and untested for inherited thrombophilia.

abstractInherited thrombophilia (IT) workup is commonly pursued in patients with venous thromboembolism (VTE). Recent American Society of Hematology 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 Registro Informatizado de Enfermedad TromboEmbólica (RIETE) registry were analyzed to compare VTE risk factors, management, and outcomes between patients who were tested for IT and untested patients, during anticoagulant treatment and after its discontinuation. Among 103 818 patients enrolled in RIETE, 21 089 (20.3%) were tested for IT, 8422 (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 such as 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 after treatment. These findings underscore the complex role of IT testing in managing VTE, supporting personalized treatment strategies that consider VTE risk factors and comorbidities. The trial was registered at www.clinicaltrials.gov as #NCT02832245.