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Thrombus
Danish researchers conducted a large, 16-year study of patients with venous thromboembolism (VTE) and found a high recurrence risk in all types of VTE.
At 6 months of follow-up, patients with unprovoked and provoked VTE had similar risk of recurrence, lower than that for patients with cancer-related VTE.
But at a 10-year follow-up, patients with unprovoked VTE had a recurrence risk similar to cancer-related VTE.
Based on these findings, the investigators concluded that risk stratification for these patients needs to be optimized.
“Our findings indicate that we may need to rethink arbitrary categorization, considering the heterogeneity of patients with venous thromboembolism,” they wrote.
They published their findings in The American Journal of Medicine.
The investigators used data from 3 nationwide Danish registries to analyze the risk of recurrent VTE in 73,993 patients with incident VTE. They stratified the patients according to whether the VTE was unprovoked, provoked, or cancer-related.
Provoked VTE occurs in patients without cancer but with other contributing factors such as surgery or trauma, and unprovoked VTE occurs without well-known provoking risk factors. Investigators did not include non-melanoma skin cancer in the cancer-related VTE classification.
Median age of the study population was 62.3 years and 54.1% were women.
During a median follow-up of 3.7 years, 9,205 patients experienced a recurrent event.
At the 6-month follow-up, the recurrence rates per 100 person-years were 6.92 for provoked, 6.80 for unprovoked, and 9.06 for cancer-related VTE.
And at the 10-year follow-up, recurrence rates were 2.22 (provoked), 2.84 (unprovoked), and 3.70 (cancer-related). This corresponded to an 18% higher adjusted relative risk of recurrence for patients with unprovoked VTE than patients with provoked VTE.
The investigators observed that at 10 years, the recurrence risk following an unprovoked VTE resembled the risk of patients with cancer-related VTE.
They suggested the mechanism for this could be a “rebound thrombosis” caused by a discontinuation of oral anticoagulants after an unprovoked VTE.
The investigators noted that the findings persisted through various sensitivity analyses “conducted to challenge the robustness of our finding.”
Two areas of concern, they wrote, arise from these findings: how long to anticoagulate patients and which patients to treat.
"Optimal duration of anticoagulation is a pivotal and an ongoing scientific and clinical concern," explained lead investigator Ida Ehlers Albertsen, MD, of Aalborg University in Denmark.
"The emergence of the non-vitamin K antagonist oral anticoagulants has changed the landscape for prevention of thrombosis, and contemporary risk stratification approaches may need to be adjusted according to these effective and safer agents."