Commentary: The Growing Role of Epidemiology in Drug Safety Regulation

Electronic health record (EHR) based postmarketing surveillance of adverse events associated with pediatric off-label medication use: A case study of short-acting beta-2 agonists and arrhythmias

PURPOSE

Use electronic health record (EHR) data to (1) estimate the risk of arrhythmia associated with inhaled short-acting beta-2 agonists (SABA) in pediatric patients and (2) determine whether risk varied by on-label versus off-label prescribing.

METHODS

Retrospective cohort study of 335 041 children ≤18 years using EHR primary care data from 2 pediatric health systems (2011-2013). A series of monthly pseudotrials were created, using propensity score methodology to balance baseline characteristics between SABA-exposed (identified by prescription) and SABA-unexposed children. Association between SABA and subsequent arrhythmia for each health system was estimated through pooled logistic regression with separate estimates for children initiating under and over 4 years old (off-label and on-label, respectively).

RESULTS

Eleven percent of the cohort received a SABA prescription, 57% occurred under the age of 4 years (off-label). During the follow-up period, there were 283 first arrhythmia events, most commonly atrial tachyarrhythmias and premature ventricular/atrial contractions. In 1 health system, adjusted risk for arrhythmia was increased among exposed children (OR 1.89, 95% CI 1.31-2.73) without evidence of interaction between label status and risk. The absolute adjusted rate difference was 3.6/10 000 person-years of SABA exposure. The association between SABA exposure and arrhythmias was less strong in the second system (OR 1.26, 95% CI 0.30-5.33).

CONCLUSION

Using EHR data, we could estimate the risk of a rare event associated with medication use and determine difference in risk related to on-label versus off-label status. These findings support the value of EHR-based data for postmarketing drug studies in the pediatric population.

The IMI PROTECT project: purpose, organizational structure, and procedures

The Pharmacoepidemiological Research on Outcomes of Therapeutics by a European ConsorTium (PROTECT) initiative was a collaborative European project that sought to address limitations of current methods in the field of pharmacoepidemiology and pharmacovigilance. Initiated in 2009 and ending in 2015, PROTECT was part of the Innovative Medicines Initiative, a joint undertaking by the European Union and pharmaceutical industry. Thirty-five partners including academics, regulators, small and medium enterprises, and European Federation of Pharmaceuticals Industries and Associations companies contributed to PROTECT. Two work packages within PROTECT implemented research examining the extent to which differences in the study design, methodology, and choice of data source can contribute to producing discrepant results from observational studies on drug safety. To evaluate the effect of these differences, the project applied different designs and analytic methodology for six drug-adverse event pairs across several electronic healthcare databases and registries. This papers introduces the organizational structure and procedures of PROTECT, including how drug-adverse event and data sources were selected, study design and analyses documents were developed, and results managed centrally.

Pharmacovigilance in Europe and North America: divergent approaches

Although international medicines regulators adopt a common system to assess the safety and efficacy of new drugs, pre-market evaluation is recognized as incomplete given the much larger post-market experience to follow. Adverse drug reactions contribute to more than 100,000 deaths in the United States annually and are among the top 10 leading causes of death. Regulators are developing active surveillance approaches to assess the risks of medicines in the post-market phase to enhance passive adverse drug reaction reporting systems that capture only one to ten percent of ADRs. The objective of this study is to compare international approaches to active surveillance and the manner in which regulatory agencies access and use post-market evidence in their decisions. A conceptual framework is used to guide the comparative analysis of pharmacovigilance governance and policy in the United Kingdom, France, the European Union, the United States and Canada using data gathered from key informant interviews and document review. While research networks are emerging internationally, we found a greater reliance on industry funding and oversight of post-market research in Europe compared to an emphasis on publicly funded programs in North America.