Reducing inappropriate infectious disease serology tests through the use of decision support in a provincial electronic health system

Diagnostic stewardship improves patient care and reduces health costs by promoting appropriate test use. Ordering serologic tests for infectious diseases can be challenging, with indications differing based on the clinical picture, previous results, or pathogens. We aimed to use our electronic health system (EHS) to provide real-time, patient-specific education on test appropriateness to reduce inappropriate testing. This observational study took place from October 2023 to 2024. The study included all users of the province-wide, integrated EHS in Alberta, Canada (population 4.9 million), which captures all laboratory orders across healthcare settings. Two diagnostic stewardship measures were assessed for 23 infectious disease serology tests: (i) Best Practice Advisories (BPAs) triggered at the point of ordering tests, and (ii) auto-cancellation rules that canceled the test upon receipt of the sample at the testing laboratory. BPAs flagged duplicate orders (within 3 days for IgM and 7 days for IgG), previously positive IgG, or missing prerequisite tests. Providers could override BPAs if necessary. After 1 year, BPAs led to 22,907 canceled tests (1.4% of targeted tests ordered). An additional 90,749 (5.3%) tests were auto-canceled upon laboratory receipt. Clinicians overrode BPAs on only 146 occasions (0.6%), with no signal of alert fatigue. BPAs prevented an estimated 16,744 phlebotomies and saved $52,049 CAD ($38,516 USD) in laboratory reagents. Auto-cancellation rules saved an additional $208,089 CAD ($153,986 USD). Integrating BPAs into an EHS effectively supports diagnostic stewardship at ordering by reducing unnecessary phlebotomies, improving test selection, and saving resources. When electronic ordering is unavailable, auto-cancellations upon laboratory receipt are an effective alternative.IMPORTANCESerology tests for past or current infections are among the most ordered laboratory investigations, yet a substantial proportion are unnecessary, particularly when patients have had recent testing or known immunity. Unneeded testing wastes resources, exposes patients to avoidable blood draws, and can produce misleading results that trigger further investigations. This study shows that two simple tools built into a province-wide electronic health record can meaningfully reduce inappropriate ordering of serologic tests across a wide range of viral and bacterial pathogens. Across nearly 1.7 million tests in 1 year, the interventions canceled more than 113,000 unnecessary tests, prevented thousands of blood draws, lowered carbon emissions, and saved roughly a quarter million Canadian dollars in laboratory reagents alone. As these tools require no additional personnel or infrastructure, the approach is widely applicable to clinical laboratories regardless of size or resource setting, supporting broader adoption of electronic decision support for efficient infection testing.