Apixaban trough anti-Xa activity was significantly associated with any bleeding (p=0.01), driven by minor bleeding, but showed no relationship with major bleeding or stroke/systemic embolism.
Observational (n=2,392)
Yes
Does apixaban-calibrated anti-FXa activity correlate with clinical outcomes such as bleeding and stroke in patients with nonvalvular atrial fibrillation?
In patients with atrial fibrillation taking apixaban, anti-Xa activity varies considerably and correlates with minor bleeding, but not with major bleeding or stroke/systemic embolism.
p-value: p=0.01
Background In patients with nonvalvular atrial fibrillation (AF), apixaban is given in doses of 5 or 2.5 mg twice daily, according to clinical characteristics. The usual on-treatment range of apixaban drug levels, as determined by apixaban-calibrated anti-factor Xa (anti-Xa) activity, has previously been measured in small cohorts; however, the association between anti-Xa activity and clinical outcomes and the predictors of variability in anti-Xa activity have not been well studied in the AF population. Methods and Results Anti-Xa activity was measured before taking the morning dose, 3 months after enrollment in the AVERROES study using a calibrated anti-Xa assay (Rotachrom). Patients with two of the following criteria—age >80; weight 133 μg/L—received 2.5 mg twice daily (n = 145), while all others received 5 mg twice daily (n = 2,247). A total of 2,392 patients were included, with median follow-up of 1.1 years. Median apixaban anti-Xa activity was 122 ng/mL (interquartile range IQR: 63–198 ng/mL) for the entire group; 99 ng/mL (IQR: 60–146 ng/mL) for the 2.5-mg group; and 125 ng/mL (IQR: 64–202 ng/mL) for the 5-mg group (p = 0.003). A relationship was evident between bleeding and anti-Xa activity (p = 0.01), which was driven by minor bleeding. No relationship was evident between major bleeding or stroke/systemic embolism and anti-Xa activity. In those receiving the 5-mg dose, estimated glomerular filtration rate, sex, and age had the strongest association with anti-Xa activity. Conclusion There is considerable variability in anti-Xa activity among AF patients receiving apixaban. Rates of major bleeding and stroke/systemic embolism were low irrespective of anti-Xa activity. Clinical Trial Registration ClinicalTrials.gov NCT00496769; https://clinicaltrials.gov/ct2/show/NCT00496769.
Bhagirath et al. (Sat,) conducted a observational in Atrial Fibrillation (n=2,392). Apixaban was evaluated on Association between anti-Xa activity and any bleeding (p=0.01). Apixaban trough anti-Xa activity was significantly associated with any bleeding (p=0.01), driven by minor bleeding, but showed no relationship with major bleeding or stroke/systemic embolism.