Background: Desloratadine (DL) is a non-sedating antihistamine, first marketed in 2001. Adverse events of supraventricular tachycardia (SVT), and atrial fibrillation and flutter (AFF) have been reported among individuals using DL. The European Medicines Agency requested MSD conduct a post-authorization safety study.
Objectives: To assess the association between DL use and incident SVT, and AFF.
Methods: We conducted a cohort study including individuals with a first prescription redemption of DL in 2001-2015. A Nordic registry-based study was conducted using health registries in Denmark, Finland, and Sweden. A common individual-level database was established. Current DL exposure was a time-varying variable defined for each prescription redemption as days’ supply plus a 4-week grace period. Unexposed periods (remote prior exposure) were defined as starting 26 weeks after the date of prescription redemption. Outcomes were incident SVT and AFF assessed separately. We analyzed the association between DL use and incidence rate (IR) of SVT and AFF using Poisson regression of number of outcomes and logarithmic transformation of follow-up time as the offset. Potential confounders were identified using causal diagrams and included country, calendar year, sex, seasonality, and history of asthma, severe rhinitis and chronic urticaria. Results are presented as IR per 100,000 person-years (PY) and incidence rate ratio with a corresponding 95% confidence interval (IRR, 95% CI).
Results: In total, 1,833,337 and 1,822,783 incident DL users were included in the study of which 2,864 and 12,378 were diagnosed with incident SVT and AFF in the primary analyses, respectively, during the study period. The IRs of SVT were 31.1 and 31.6 per 100,000 PY during DL exposed and DL unexposed periods. No significant association was seen between DL use and incidence of SVT (Unadjusted: IRR=0.99, 95% CI: 0.89; 1.10 Adjusted: IRR=1.03, 95% CI: 0.92; 1.15). The IRs of AFF were 142.8 and 136.2 per 100,000 PY during DL exposed and DL unexposed periods. A significant association between current DL exposure and IR of AFF was seen (unadjusted IRR=1.05, 95% CI: 1.00; 1.10). A 6% increase in the IR of AFF during the exposed periods was seen for the adjusted analysis (IRR=1.06, 95% CI 1.01; 1.12). The association was strongest following the first prescription (IRR=1.24 95% CI 1.13;1.36).
Conclusion: A 6% increase in the IR of AFF was seen among individuals currently exposed to DL. No association between current DL exposure and SVT was found.
