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Patients with nonvalvular atrial fibrillation who were prescribed apixaban vs rivaroxaban had a lower rate of ischemic stroke or systemic embolism and bleeding, according to study results published in the Annals of Internal Medicine.
In this new-user, active-comparator, retrospective cohort study, patients aged >18 years in the Optum Clinformatics database who received a diagnosis of atrial fibrillation or atrial flutter were identified (n=99,878). In this cohort, 59,172 and 40,706 patients had been recently prescribed apixaban (5 mg) or rivaroxaban (20 mg), respectively between December 2012 and January 2019. After 1:1 propensity score matching, 39,351 patients prescribed apixaban and 39,351 prescribed rivaroxaban were retained. All baseline characteristics were well-balanced after propensity matching. The study’s primary efficacy outcome was a composite of ischemic stroke or systemic embolism. The primary safety outcome was a composite of gastrointestinal bleeding or intracranial hemorrhage.
In the unmatched efficacy analysis, 342 patients newly prescribed apixaban had a stroke or systemic embolism (7.5 events per 1000 person-years) compared with 255 among patients receiving rivaroxaban (7.9 events per 1000 person-years; hazard ratio [HR], 0.94, 95% CI, 0.80-1.10). After propensity score matching, 206 and 251 patients receiving apixaban and rivaroxaban, respectively had a stroke or systemic embolism (6.6 and 8.0 events per 1000 person-years, respectively; HR, 0.82; 95% CI, 0.68-0.98).
In the unmatched safety analysis, 727 and 697 patients receiving apixaban and rivaroxaban, respectively had a major bleeding episode (16.1 and 21.5 events per 1000 person-years, respectively; HR, 0.73; 95% CI, 0.66-0.81). After propensity score matching, the rate of major bleeding for patients receiving apixaban and rivaroxaban was 12.9 and 21.9 per 1000 person-years, respectively (HR, 0.58; 95% CI, 0.52-0.66).
Study limitations include the inability to balance unmeasured confounding factors, the lack of accounting for time-varying confounders that may impact the risk for stroke or bleeding, and a lack of evaluation of long-term outcomes.
These findings are consistent with those from randomized controlled trials. “Until head-to-head clinical trial data are available, the results of our study, which included a large sample of patients seen in routine care, provides updated evidence in support of apixaban for treating nonvalvular atrial fibrillation,” concluded the study authors.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Reference
Fralick M, Colacci M, Schneeweiss S, Huybrechts KF, Kueiyu JL, Gagne JJ. Effectiveness and safety of apixaban compared with rivaroxaban for patients with atrial fibrillation in routine practice: A cohort study [published online March 10, 2020]. Ann Intern Med. doi:10.7326/M19-2522.
