More bleeds and clots in afib patients who took NSAIDs

Patients with atrial fibrillation who were prescribed NSAIDs had more serious bleeding and thromboembolic events than those not on NSAIDs, a new Danish study found.

The observational cohort study included more than 150,000 patients with atrial fibrillation who were hospitalized in Denmark between 1997 and 2011. During a median follow-up of 6.2 years, 35.6% of them were prescribed an NSAID. In the overall patient group, 11.4% had a serious bleed and 13% had a thromboembolism, which were the study's primary outcomes. Results were published in the Nov. 18 Annals of Internal Medicine.

Within 14 days of taking NSAIDs, the risk of a bleed or thromboembolism was 3.5 per 1,000 patients compared to 1.5 per 1,000 patients in those not taking NSAIDs (difference, 1.9 events per 1,000), according to the researchers' calculations at 3 months from study inclusion. In patients who were taking oral anticoagulant therapy, the increase in risk associated with NSAID use was even greater, with an additional 2.5 events per 1,000 patients. NSAIDs were associated with an increased risk for both adverse outcomes across all antithrombotic regimens and NSAID types. A dose-response effect was found, with NSAID doses above the recommended minimum being associated with a greater risk for bleeding.

Use of NSAIDs in atrial fibrillation patients was associated with an increased risk for serious bleeding even when the drugs were only used for a short time, the researchers concluded. Although this association had been assumed, the magnitude of the hazard—which the researchers calculated to be 1 serious bleeding event per 400 to 500 patients on NSAIDs—had not previously been defined. NSAIDs were also shown to be associated with thromboembolism risk, which is important because it suggests that prescribing an NSAID to a patient with atrial fibrillation could counteract the effects of oral anticoagulant therapy, the authors said.

Based on these results, physicians should use caution prescribing NSAIDs to atrial fibrillation patients, avoiding them unless other options, such as physical therapy and acetaminophen or other drugs, have failed, the study authors concluded. They acknowledged that the study was limited by its observational design, inclusion of only patients sick enough to be hospitalized, and unmeasured confounders.