Query 16-03: Preventable adverse drug reactions (ADR) as percentage of total ADRs
This project was funded in June 2016 for two years. The query will be addressed in two phases: i) in phase I, we will conduct a retrospective chart review of patients diagnosed with an ADE to determine the preventability of the event, identify contributing factors, determine the ADE-related harm and interventions required, and identify the kind of drug re-exposure that would likely cause a future repeat ADE; ii) in phase II, we will link phase I data to PharmaNet data to determine the proportion of ADE patients that were re-exposed to contraindicated medications and the specialty of the prescribing physician. Since receiving funding, we have obtained ethics approvals, refined the research protocol and data collection forms, and have hired two pharmacists to complete chart reviews.
At this point in time, we have completed phase I data collection. Data of 1234 patients were studied and 1356 ADEs were found. ADEs due to adverse drug reactions (35%) and non-adherence (19%) were most common, most moderate (65%) or severe (31%) and two-thirds required either major or minor interventions in hospital. We deemed 64% (95%CI:62-67%) of ADEs to be preventable and 29% (95%CI:26-31%) were repeat events. The most commonly implicated drug classes were coumarin derivatives (9%), and opiate agonists (9%), and common contributing factors included inadequate patient counselling (16%), lack of follow-up after a change in regimen (12%), and insufficient laboratory monitoring (11%). On multivariable patient-level analyses, mental health diagnoses, diabetes, and a prior ADE to the same drug were associated with patients having preventable ADEs. Diabetes and renal failure were significant in association with patients having repeat ADEs. These results were presented at the Canadian Association of Emergency Physicians (CAEP) and the Canadian Association for Health Services and Policy Research (CAHSPR) conferences.