BCR-ABL Testing by Polymerase Chain Reaction in Patients With Neutrophilia: The William Beaumont Hospital Experience and the Case for Rational Laboratory Test Requests.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm resulting from the fusion of the BCR-ABL genes, forming the Philadelphia chromosome. The diagnosis is often suspected when there is leukocytosis with left shift and basophilia. Confirmation of the diagnosis requires a demonstration of BCR-ABL by polymerase chain reaction. Using data from the William Beaumont laboratory data registry, we conducted a retrospective review of all the orders for BCR-ABL tests sent to the clinical pathology laboratory between March 11, 2014 and September 12, 2014. We concluded that the presence of concurrent neutrophilia and basophilia has a sensitivity of 100% (95% CI, 69.15% to 100%) and specificity of 100% (95% CI, 93.15% to 100%) in the initial diagnosis of CML. Our results suggest that the presence of both neutrophilia and basophilia should be used as a threshold for the placement of orders for BCR-ABL in the initial diagnosis of CML in patients with leukocytosis with left shift and provide a basis for a reduction in health care spending. Restricting BCR-ABL tests to this population would save approximately $198 million annually in national health care spending.