Introduction With an aging population placing pressure on Canada’s healthcare system, reducing unnecessary ordering of tests is one way of improving safety without compromising quality of care. Unnecessary care is not only wasteful, it can have implications for patient safety, such as exposure to radiation from diagnostic imaging (DI) tests: 2–3 computed tomography (CT) scans involve amounts of radiation that have been associated with increased cancer risk. Choosing Wisely Canada (CWC), a physician driven campaign aimed to reduce unnecessary care, could help to promote more appropriate ordering practices. Through CWC, Canadian specialty societies have produced numerous recommendations to avoid common tests, treatments, and procedures that may be unnecessary and harmful.

Objectives The recommendations have been implemented in many Canadian practice settings, and one large community hospital in Ontario, Canada has made it a strategic priority. Specifically, the hospital employed various interventions such as changing medical directives and electronic order sets, engaging leadership, and holding educational meetings. Through a pre-post study, this hospital found that laboratory testing in the ED was reduced by 31%, representing approximately £88 877 over one year. Although these preliminary results indicated decreases in laboratory test ordering, our research team is currently conducting a more rigorous study, as pre-post studies are problematic for causal attribution.

Therefore, the purpose of this research is to evaluate the implementation of DI- and laboratory-related CWC recommendations into the emergency department at a large community hospital, including ehealth interventions.

Method We will use an explanatory sequential mixed-methods design to explain and explore the impact of CWC upon this hospital’s emergency department testing practices. We will use interrupted time series analyses to assess changes in monthly testing rates one year before and three years after the implementation of interventions. We will also conduct key informant interviews with clinicians and hospital leadership to gain insight into how and why the effects were achieved in this context.

Results Findings from these methods will be triangulated and used to develop an implementation framework that can be generalized for use in other settings.

Conclusions In order to promote patient safety and the responsible use of health care resources, it is critical to determine ways to reduce unnecessary tests. Through this comprehensive program evaluation, we plan to gain insight into what interventions are most impactful.