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 realworld 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.

practice. All HTA bodies recommended the three biologic therapies for use in patients with moderate to severe plaque psoriasis who have failed to respond to standard systemic therapies with discontinuation rules if no response was observed after 12-16 (16-20: ixekizumab (SMC)) weeks. Conclusions: The evidence base, and HTA agency decisions, for guselkumab, ixekizumab, and brodalumab submissions were principally aligned. As more biologics are being approved, understanding the requirements of HTA, and undertaking holistic evidence generation, will play a crucial role in enabling access to the novel biologics.