Abstract
BackgroundConventional systems of drug surveillance lack a seamless workflow, which makes it crucial to have an active drug surveillance system that proactively assesses adverse drug events.ObjectiveThe aim of this study was to develop a seamless, Web-based workflow for comparing the safety and effectiveness of drugs in a database of electronic medical records.MethodsWe proposed a comprehensive integration process for cohort surveillance using the National Taiwan University Hospital Clinical Surveillance System (NCSS). We studied a practical application of the NCSS that evaluates the drug safety and effectiveness of novel oral anticoagulants (NOACs) and warfarin by cohort tree analysis in an efficient and interoperable platform.ResultsWe demonstrated a practical example of investigating the differences in effectiveness and safety between NOACs and warfarin in patients with nonvalvular atrial fibrillation (AF) using the NCSS. We efficiently identified 2357 patients with nonvalvular AF with newly prescribed oral anticoagulants between 2010 and 2015 and further developed 1 main cohort and 2 subcohorts for separately measuring ischemic stroke as the clinical effectiveness outcome and intracranial hemorrhage (ICH) as the safety outcome. In the subcohort of ischemic stroke, NOAC users exhibited a significantly lower risk of ischemic stroke than warfarin users after adjusting for age, sex, comorbidity, and comedication in an intention-to-treat (ITT) analysis (P=.01) but did not exhibit a significantly distinct risk in an as-treated (AT) analysis (P=.12) after the 2-year follow-up. In the subcohort of ICH, NOAC users did not exhibit a different risk of ICH both in ITT (P=.68) and AT analyses (P=.15).ConclusionsWith a seamless and Web-based workflow, the NCSS can serve the critical role of forming associations between evidence and the real world at a medical center in Taiwan.
Highlights
Randomized controlled trials are considered the gold standard for the approval of new drugs, these trials may be ineffective in detecting adverse drug events (ADEs) in real-world clinical practice
The outcomes of interest, including ischemic stroke and intracranial hemorrhage (ICH), were irreversible events. To ensure that these irreversible outcomes that occurred during the follow-up period were incident events, which refer to new events, we identified 2 subcohorts, excluding those who had the irreversible outcomes within 1 year before the index date, and conducted statistical analysis separately
We have successfully demonstrated the implementation of an application for assessing the clinical effectiveness and safety of novel oral anticoagulants (NOACs) and warfarin
Summary
Randomized controlled trials are considered the gold standard for the approval of new drugs, these trials may be ineffective in detecting adverse drug events (ADEs) in real-world clinical practice. The obstacle to address, when using EMRs to implement a real-world postmarketing drug surveillance system, will be to reduce the differences between those who receive a specific drug and their comparators (the so-called selection bias). To avoid such bias, matching is one approach that can be followed to minimize the confounding effects resulting from such discrepancies [6,7]. Conventional systems of drug surveillance lack a seamless workflow, which makes it crucial to have an active drug surveillance system that proactively assesses adverse drug events
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