Optimized Test Utilization Significantly Increased the Positive Detection Rate for Myeloproliferative Neoplasms

Background: Molecular testing for myeloproliferative neoplasms (MPNs) without defined clinical criteria can lead to inefficient laboratory utilization without proportional diagnostic benefit. Methods: We evaluated the impact of implementing clinical acceptance criteria, including unexplained abnormal blood counts, unusual-site thrombosis, unexplained hepatosplenomegaly, and/or leukoerythroblastic blood film for gene (JAK2, CALR, MPL and/or BCR::ABL1) testing of patients with suspected MPNs in Hamilton, Canada and surrounding areas. The impact of testing criteria on ordering practices and diagnostic yields was assessed by retrospective examination of 3590 MPNs test requests submitted between 1 January and 31 December 2025; including 5.5 months of permissive testing (pre-implementation period), 2 months with a transition in testing criteria (grace period) and 4.5 months with restricted testing (post-implementation period). During the post-implementation period, the Laboratory also transitioned from sequential single-gene PCR-based assays to an MPN next-generation sequencing (NGS) panel for DNA-based MPN testing. Results: Our results show that test volumes decreased significantly from 1835 in the pre-implementation period to 1050 post-implementation, while the positivity rate increased from 12% to 17% (χ2 = 12.26, p = 0.001). Patients with elevated platelet counts (237 of 1050 tested) demonstrated the highest positivity rate of 35% (n = 83/237). JAK2 V617F represented the highest proportion of all detected mutations at 73% (n = 127/174). Conclusions: These findings show that implementing appropriate pre-test clinical criteria significantly improved MPN test utilization and diagnostic yield.