Recurrence risk is significant among all patients with venous thromboembolism (VTE), though recurrence is most frequent in patients with cancer-related VTE, according to a nationwide Danish study.
Ida Ehlers Albertsen, MD, of Aalborg (Denmark) University Hospital and her coauthors followed 73,993 patients who were diagnosed with incident VTE during January 2000–December 2015. The patients’ VTEs were classified as either cancer-related, unprovoked (occurring in patients without any provoking factors), or provoked (occurring in patients with one or more provoking factors, such as recent major surgery, recent fracture/trauma, obesity, or hormone replacement therapy).
The researchers found similar risks of recurrence among patients with unprovoked and provoked VTE at 6-month follow-up, with rates per 100 person-years of 6.80 and 6.92, respectively. By comparison, the recurrence rate for cancer-related VTE at 6 months was 9.06. The findings were reported in the American Journal of Medicine.
However, at 10-year follow-up the rates were 3.70 for cancer-related VTE, 2.84 for unprovoked VTE, and 2.22 for provoked VTE, which reinforces the belief that “unprovoked venous thromboembolism is associated with long-term higher risk of recurrence than provoked venous thromboembolism.”
Additionally, at 10-year follow-up, the absolute recurrence risk of cancer-related VTE and unprovoked VTE were both at approximately 20%, with recurrence risk of provoked VTE at just above 15%. Compared with the recurrence risk of provoked VTE at 10-year follow-up, the hazard ratios of cancer-related VTE and unprovoked VTE recurrence risk were 1.23 (95% confidence interval, 1.13-1.33) and 1.18 (95% CI, 1.13-1.24), respectively.
The coauthors observed several challenges in comparing their study to previous analyses on recurrent risk, noting that the definition of provoked VTE “varies throughout the literature” and that the majority of VTE studies “provide cumulative incidence proportions and not the actual rates.” They also stated that indefinite or extended therapy for all VTE patients comes with its own potential complications, even with the improved safety of non–vitamin K antagonist oral anticoagulants, writing that “treatment should be given to patients where the benefits outweigh the risks.”
Despite the differences in recurrence rates at 6-month and 10-year follow-up, the coauthors suggested that enough risk was present in all types to warrant additional studies and reconsider how VTE patients are categorized.
“A high recurrence risk in all types of venous thromboembolism indicates that further research is needed to optimize risk stratification for venous thromboembolism patients,” they wrote.
The study was partially funded by a grant from the Obel Family Foundation. Some authors reported financial disclosures related to Janssen, Bayer, Roche, and others.
SOURCE: Albertsen IE et al. Am J Med. 2018 Sep;131(9):1067-74.e4.