BACKGROUND: More information is often thought to improve medical decision-making, which may lead to test overuse. This study assesses which out of 15 laboratory tests contribute to diagnosing the underlying cause of anaemia by general practitioners (GPs) and determines a potentially more efficient subset of tests for setting the correct diagnosis. METHODS: Logistic regression was performed to determine the impact of individual tests on the (correct) diagnosis. The statistically optimal test subset for diagnosing a (correct) underlying cause of anaemia by GPs was determined using data from a previous survey including cases of real-world anaemia patients. RESULTS: Only 9 (60%) of the laboratory tests, and patient age, contributed significantly to the GPs' ability to diagnose an underlying cause of anaemia (CRP, ESR, ferritin, folic acid, haemoglobin, leukocytes, eGFR/MDRD, reticulocytes and serum iron). Diagnosing the correct underlying cause may require just five (33%) tests (CRP, ferritin, folic acid, MCV and transferrin), and patient age. CONCLUSIONS: In diagnosing the underlying cause of anaemia a subset of five tests has most added value. The real-world impact of using only this subset should be further investigated. As illustrated in this case study, a statistical approach to assessing the added value of tests may reduce test overuse.

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Keywords Anemia, Data analysis, statistical, Diagnoses and laboratory examinations, General practice, Optimal testing, Overuse
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Journal B M C Medical Informatics and Decision Making
Kip, M.M.A. (Michelle M A), Oonk, M.L.J. (Martijn L J), Levin, M.-D, Schop, A. (Annemarie), Bindels, P.J.E, Kusters, R. (Ron), & Koffijberg, H. (2020). Preventing overuse of laboratory diagnostics: a case study into diagnosing anaemia in Dutch general practice. B M C Medical Informatics and Decision Making, 20(1). doi:10.1186/s12911-020-01198-8