Repeat exposures to culprit medications are a common cause of preventable adverse drug events. Health information technologies have the potential to reduce repeat adverse drug events by improving information continuity. However, they rarely interoperate to ensure providers can view adverse drug events documented in other systems. The investigators designed ActionADE to enable rapid documentation of adverse drug events, and communication of standardized information across health sectors by integrating ActionADE with legacy systems.

The investigators will leverage ActionADE's implementation to conduct a randomized trial on patients diagnosed with adverse drug reactions in the main trial. This study will take place in Vancouver, British Columbia, Canada.

Medication use is rising due to an aging population and expanding treatment indications for chronic diseases. Simultaneously, adverse drug events-harmful and unintended events related to medication use or misuse-have increased. In Canada, adverse events to outpatient medications cause over two million emergency department visits and 700,000 hospital admissions, costing over $1 billion in healthcare expenditures annually. Optimizing the benefits of medications while limiting their potential for harm is a public health priority across patient populations, health settings and medical disciplines.

Patients with adverse drug events often seek care in hospitals due to the unexpected and serious nature of these events. After assessment and treatment, patients are discharged back into the care of a community-based provider who often cannot access the hospital's medical record, may not receive a legible or detailed discharge summary, and is at risk of either re-starting the culprit medication for chronic disease management in the case of an adverse drug reaction. The investigators developed ActionADE to address this type of information discontinuity. ActionADE was integrated to a province-wide network that links all pharmacies in British Columbia to a central data system, allowing users to see their patient's medication dispensing history.

The investigators will conduct a triple-blind randomized controlled trial to evaluate the effectiveness of ActionADE on preventing subsequent adverse drug reactions. The trial will take place in two urban tertiary care (Vancouver General and Saint Paul's Hospitals) and one urban community hospital (Lions Gate Hospital) within the Greater Vancouver area, in British Columbia, Canada. Other hospitals may be added to accelerate recruitment into the trial if approved by the British Columbia Ministry of Health.

The primary objective of the main trial is to evaluate the effect of providing information continuity about adverse drug reactions using ActionADE on culprit drug re-dispensations over 12 months compared to standard care. Secondary objectives are to evaluate the effect on outpatient and emergency department visits, admissions, hospital-days and mortality.

Inclusion Criteria:

• Adults 19 years of age or older presenting to the participating emergency departments with an adverse drug reaction to a prescribed outpatient medication that was reported in ActionADE.

Exclusion Criteria:

• Patients whose adverse drug event is categorized as life threatening will be excluded.
• Patients without a Provincial Health Number will be excluded as this will prevent linkage with PharmaNet and other administrative data for outcomes ascertainment.
• Patients diagnosed with adverse drug events to culprit medications not on the provincial formulary will be excluded as we will not be able to ascertain re-dispensations outcomes for these medications using PharmaNet data.

Study participants, outcomes assessors, and study investigators will be blinded to treatment allocation. Community pharmacists cannot be blinded to the intervention, as we are studying the change in pharmacists' dispensing behavior due to the provision of new adverse drug event information. The information will only appear for patients in the experimental arm.