Anticoagulant therapy, commonly prescribed for the treatment of venous thromboembolism (VTE), presents a bleeding risk that varies over time. This risk is most concerning during the first six months of treatment, after which it significantly decreases, potentially affecting the benefit-risk ratio.
Understanding Venous Thromboembolism and Anticoagulant Therapy
Venous thromboembolism (VTE) requires urgent and sometimes prolonged anticoagulant treatment, depending on the clinical context. It is not uncommon for this treatment to be prescribed indefinitely, posing a bleeding risk that looms like a sword of Damocles. This risk is influenced by multiple factors, including the type of anticoagulant, the patient’s age, and the duration of treatment.
Challenges in Assessing Benefit-Risk Ratio
Controlled trials often fall short in fully appreciating the benefit-risk ratio of various therapeutic strategies throughout the evolution of VTE. The decision to discontinue anticoagulant treatment is frequently challenging. Observational studies or registries fill this gap, as demonstrated by a Swedish cross-sectional case-control study initially involving 128,922 VTE cases collected from national registries since January 1, 2014.
Study Objective and Methodology
The study aimed to determine the bleeding risk associated with anticoagulant treatment, specifically direct oral anticoagulants (DOACs), based on the treatment period: initial (0 to 6 months) versus prolonged (6 months to 5 years). This was compared to a control group from the general population without VTE. Major bleeding incidents were considered in terms of incidence rates per 100 person-years.
Ultimately, 36,115 patients with VTE without underlying cancer were matched using propensity score methods to an equal number of controls.
Findings: Initial Treatment Phase
During the initial phase of DOAC treatment (0-6 months), intergroup comparison revealed an increased bleeding risk in the treated group, with an incidence rate (per 100 person-years) estimated at 1.07% versus 0.29% in the control group, leading to an incidence rate difference of 2.19 (95% CI: 1.89-2.49).
The increased risk was higher in women, with a corresponding value of 2.69 (versus 1.73 in men), and in older patients, with the incidence rate difference reaching 4.44 beyond 80 years of age.
Findings: Prolonged Treatment Phase
During the prolonged therapeutic phase (6 months to 5 years), the same intergroup comparison showed a lower increased bleeding risk, with the incidence rate difference estimated at 0.70 (95% CI: 0.52-0.89). Furthermore, this increased risk was independent of gender or age.
Implications of the Study
DOACs present a bleeding risk that appears to decrease over time, at least when used in the treatment of VTE, whether it involves deep vein thrombosis or pulmonary embolism. The increased risk compared to a control population is particularly high during the first six months of treatment, especially in women and older patients. However, during prolonged treatment, this risk decreases and no longer seems to be influenced by gender or age.
These results, derived from a registry study, are inherently retrospective and not immune to criticism. Ideally, they should be confirmed by prospective studies. Nonetheless, they encourage close monitoring of DOAC treatment during the first six months, particularly in women and older individuals.
Subsequently, vigilance remains important, but the bleeding risk appears to be less concerning, at least within a follow-up period not exceeding five years. The decision to discontinue DOACs in the absence of VTE recurrence will need to be made at some point, as the study results do not argue for unnecessarily prolonging treatment.
**Source:** [Medscape](https://francais.medscape.com/s/voirarticle/3612631)
