Abstract P250: Emergency Room Consultations and Hospitalizations Following Generic Clopidogrel Commercialization in Quebec, Canada

Abstract

Background: Clopidogrel is widely used to prevent atherothrombotic events. Federal standards regulate bioequivalence of generic and brand-name drugs through comparative bioavailability studies but does not regulate clinical equivalence nor tolerability in “real-life” settings. We evaluated the impact of the generic clopidogrel commercialization on some adverse events: emergency room consultations (ER) or hospitalizations. Methods: This is an interrupted time series analysis using the Quebec Integrated Chronic Disease Surveillance System. Rates of adverse events for clopidogrel users (n=75,130) aged ≥ 66 years were calculated monthly, 12 months before and 12 months after generics commercialization. Periods before and after generics commercialization were compared by negative binomial segmented regression models for all users with a specific variable for generic and brand-name users after generics commercialization. Results: Generic clopidogrel analogs (n=6) were commercialized in 2012. There was an approximated monthly mean rate of 157 adverse events per 1000 brand-name and generic users-month. After generics commercialization, there was an immediate increase in rates of adverse events for generic vs. brand-name users (22 vs. 2%, p < 0.0001, Figure 1). This was explained by increased rates of ER (+22%) and hospitalizations (+20%) the month of generic clopidogrel commercialization. Hospitalization trend up to 1 year after generics commercialization was stable for generic users but reduced for brand-name users (-0.9 vs. -2.9%, p = 0.01), while ER trends were comparable (-1.1 vs. -1.8%, p = 0.2443). Conclusion: Among generic clopidogrel users, increased rates of ER and hospitalizations were observed soon after generics commercialization. The trend of hospitalizations was also affected following generic clopidogrel commercialization. Risk and survival analysis studies controlling for potential confounding are required to better characterize generic substitution.