Trends in Hospital Visits for Generic and Brand-Name Warfarin Users in Québec, Canada: A Population-Based Time Series Analysis

Clinical equivalence of generic and brand-name drugs used in cardiology: what do we know?

The problem of using generics in the treatment of patients with cardiovascular diseases remains relevant for more than a decade. The concern of doctors, pharmacists and patients is not diminishing with the constant rise in cardiovascular morbidity and mortality worldwide. Based on a systematic review of 186 publications, physicians identified concerns about the quality, reliability and replaceability of original drugs; pharmacists have shown the highest level of generic approval. Patients distrust of generics was revealed, caused by a lack of information, concerns about packaging, and negative experience of replacing the original drug. Three meta-analyzes compared generic and original drugs of cardiovascular groups in terms of efficacy and safety. A 2008 meta-analysis (47 studies, 9 classes of cardiovascular drugs) assessed the effect on mild outcomes, a 2016 meta-analysis (74 studies, 7 classes of drugs) also assessed side effects. The cumulative effect revealed a small and nonsignificant difference, which indicated that there was no superiority of original drugs over generics; there were no differences in the frequency and severity of side effects between generics and original drugs. A 2020 meta-analysis (72 studies, 9 drug classes) assessed the frequency of hospital admissions (including emergency department consultations, hospitalizations) and found a significant increase in the risk for generics for any reason (14%), but not for cardiac vascular diseases. A review of 8 cohort studies evaluating antihypertensive drugs for long-term cardiovascular outcomes, duration of retention, and substitution effect did not find significant differences between generics and brands. In a systematic review of studies comparing warfarin and generics, there were no significant differences in international normalized ratio and the incidence of thromboembolic and hemorrhagic complications; however, in one study, the frequency of hospital visits was 10% higher for generics. A systematic review of studies comparing clopidogrel versus generics shows drug comparability for major cardiovascular events and mortality. A review of 5 cohort studies evaluating originator statins and generics showed comparable rates of all-cause mortality and major cardiovascular events, except for one study with conflicting results. Meta-analyzes and large observational studies indicate that generics are not the worst efficacy, sometimes even surpass that of original drugs and can be justifiably used in clinical practice.

Using Data from the Canadian Post-marketing Spontaneous Pharmacovigilance System for Drug Safety Research: A Feasibility Study

INTRODUCTION

Post-marketing studies involve the detection and interpretation of potential problems associated with the use of a given drug. Post-marketing spontaneous pharmacovigilance systems, such as the Canada Vigilance program, may constitute a gold mine of free data for drug safety research. However, the quantity and the quality of data remain to be demonstrated.

OBJECTIVE

To assess the feasibility to use the Canada Vigilance database for academic drug safety research, and to document the characteristics of data that are extractable.

METHODS

This is a descriptive retrospective analysis study design. The beta-blocker and anticoagulant adverse reactions (AR) in Canada were analyzed. Tests for data extraction from the Canada Vigilance database were performed in October 2019; data were then available from January 1, 1966 to June 30, 2019.

RESULTS

There were 41 variables with extractable data. For anticoagulants, data were extracted in Excel and.pdf file format, while it was only plain text.pdf files for beta-blockers. Overall, there were 4707 reported ARs with the use of anticoagulants and 6332 cases reported for beta-blockers. The trend of ARs related to anticoagulants steadily increased in the study period, with a notable increase in 2009 while direct oral anticoagulants were marketed. The proportion of missing data varied from 0 to 98%, but most important variables were all available. It was not possible to distinguish brand names and generic drugs in the database.

CONCLUSION

It seems feasible to use data from the Canadian Post-marketing Spontaneous Pharmacovigilance System for academic drug safety research. Upcoming studies should validate the quality of reports compared to actual medical charts.

Public Health Outcomes May Differ After Switching from Brand-Name to Generic Angiotensin II Receptor Blockers

Background

It is unclear whether generics are as safe as brand-name drugs in cardiology. For public health surveillance purposes, we evaluated if switching from the brand-name losartan, valsartan, or candesartan impacted the occurrence of the following outcomes: emergency room (ER) consultations, hospitalizations, or death.

Study Design

This was a retrospective cohort study.

Methods

This study was conducted in the Quebec Integrated Chronic Disease Surveillance System, including healthcare administrative data of the population of Quebec, Canada. We included brand-name users of losartan, valsartan, or candesartan aged ≥ 66 years who had undergone ≥ 30 days of stable treatment on the brand-name drug prior to cohort entry (substitution time-distribution matching was used to prevent immortal time bias). Outcomes up to 1 year were compared between groups using multivariable Cox proportional hazards regression models (validity assumptions were verified).

Results

In our cohorts (losartan, n =15,783; valsartan, n =16,907; candesartan, n =26,178), mean age was 76–78 years, 59–66% were female, 90–92% had hypertension, and 13–15% had heart failure. Validity assumptions were violated for losartan only. For patients switched to generic valsartan, the hazard ratio (95% confidence interval) was 1.07 (0.99–1.14) for ER consultation, 1.26 (1.14–1.39) for hospitalization, and 1.01 (0.61–1.67) for death. The corresponding rates for candesartan were 1.00 (0.95–1.05), 0.96 (0.89–1.03), and 0.57 (0.37–0.88), respectively.

Conclusions

We observed an increased risk of hospitalizations for patients switched to generic valsartan, and a decreased risk of death for patients switched to generic candesartan, compared with those who continued taking the brand-name drug. The differences between generic and brand-name drugs may lead to some differences in public health outcomes, but this safety signal must be further studied using other cohorts and settings.

Electronic supplementary material

The online version of this article (10.1007/s40268-020-00307-2) contains supplementary material, which is available to authorized users.

Are Generic Drugs Used in Cardiology as Effective and Safe as their Brand-name Counterparts? A Systematic Review and Meta-analysis

BACKGROUND

Previous systematic reviews (2008; 2016) concluded similarity in outcomes between brand-name and generic drugs in cardiology, but they included ≥ 50% comparative bioavailability studies, not designed or powered to detect a difference in efficacy or safety between drug types. We aimed to summarise best-evidence regarding the effectiveness and safety of generic versus brand-name drugs used in cardiology.

METHODS

For this systematic review of the literature, scientific databases (MEDLINE and EMBASE) were searched from January 1984 to October 2018. Original research reports comparing the clinical impact of brand-name versus generic cardiovascular drugs on humans treated in a real-life setting, were selected. Meta-analyses and subgroup analyses were performed. Heterogeneity (I²) and risk of bias were tested.

RESULTS

Among the 3148 screened abstracts, 72 met the inclusion criteria (n ≥ 1,000,000 patients, mean age 65 ± 10 years; 42% women). A total of 60% of studies showed no difference between drug types, while 26% concluded that the brand-name drug was more effective or safe, 13% were inconclusive and only 1% concluded that generics did better. The overall crude risk ratio of all-cause hospital visits for generic versus brand-name drug was 1.14 (95% confidence interval: 1.06-1.23; I²: 98%), while it was 1.05 (0.98-1.14; I²: 68%) for cardiovascular hospital visits. The crude risk ratio was not statistically significant for randomised controlled trials only (n = 4; 0.92 [0.63-1.34], I²: 35%).

CONCLUSION

The crude risk of hospital visits was higher for patients exposed to generic compared to brand-name cardiovascular drugs. However, the evidence is insufficient and too heterogeneous to draw any firm conclusion regarding the effectiveness and safety of generic drugs in cardiology.

Did Generic Clopidogrel Commercialization Affect Trends of ER Consultations and Hospitalizations in the Population Treated with Clopidogrel?

BACKGROUND

Clopidogrel has been widely used to prevent atherothrombotic events. Since 2011, pharmacists have offered their patients the opportunity to switch to generic clopidogrel, an economic alternative. Whether bioequivalence of generic cardiovascular drugs translates into clinical equivalence at a population level remains unclear and needs to be further documented.

OBJECTIVE

We aimed to evaluate the impact of generic clopidogrel commercialization on adverse events (AEs): hospitalizations or emergency room (ER) consultations.

METHODS

This is an interrupted time series analysis using the Quebec Integrated Chronic Disease Surveillance System. We included all patients ≥ 66 years old who were users of the brand-name clopidogrel or a generic version (n = 6) 24 months before and up to 12 months after generics commercialization. Rates of AEs were computed, and periods before and after generics commercialization were analyzed by segmented regression models along with exploratory analyses (generic vs. brand name). Sensitivity analyses were also performed using stratification of the time series by (1) sex, (2) the number of prevalent cardiovascular comorbidities, and (3) socioeconomic status.

RESULTS

Time series were constituted of 89,525 clopidogrel users (mean age 78 years, 45% women, 71% ischemic heart disease, 34% stroke). For all users, there was a mean rate of 157 AEs per 1000 user-months, stable trend before (-0.1% [95% confidence interval -0.3 to 0.1] and after (0.0% [- 0.5 to 0.6]) generics commercialization. In exploratory analyses, once generic clopidogrel versions were commercialized, rates of AEs were 19.2% (95% CI 11.7-26.7) higher for generic versus brand-name users. This difference persisted up to 1 year. Sensitivity analyses yielded similar results.

CONCLUSIONS

The population treated with clopidogrel had similar rates of hospitalizations or ER consultations before and after generics commercialization. However, differences in rates of hospitalizations or ER consultations between generic and brand-name clopidogrel users may represent a drug safety signal which remains to be validated. Using a different study design, permitting adjustment for potential confounders, could be useful in this regard.