The complexity of "provoked" venous thromboembolism: one treatment plan does not fit all Commentary on the HI-PRO Trial.

The decision whether to continue patients diagnosed with venous thromboembolism (VTE) on anticoagulation after the initial treatment period is often a nuanced decision. Many patients will have one or more transient risk factors associated with a time-limited increased risk for VTE. Transient risk factors are further divided into major, such as joint replacement, or minor, such as prolonged travel, which defines the magnitude of risk for an initial VTE. In addition, major transient risk factors generally carry a lower risk for recurrent VTE compared to minor transient risk factors. However, many patients will also have one or more persistent VTE risk factors, which further increase the risk for recurrence. Some persistent risk factors, such as inflammatory bowel disease, are associated with a high enough risk for recurrent VTE that guidelines recommend indefinite anticoagulation in this setting. There are multiple other persistent risk factors that carry a lower risk for recurrent VTE, however, such as chronic renal insufficiency and obesity. The High-Risk Patients with Provoked Venous Thromboembolism (HI-PRO) trial sought to assess the efficacy and safety of extended thromboprophylaxis for the prevention of recurrent VTE in patients with an initial provoked VTE and at least one persistent risk factor. The study found a lower risk of recurrent VTE in the thromboprophylaxis cohort, challenging the traditional time-limited treatment for provoked VTE, but heterogeneity of the study population and small sample size preclude identification of which subsets of patients could safely discontinue anticoagulation. We consider the conundrum of "provoked VTE" in this review.