Using the absolute neutrophil count as a stand-alone test in a hematology/oncology clinic: an abbreviated test can be preferable.

Abstract

More is not always better. We hypothesized that clinicians prefer an abbreviated but focused test to one that provides more--but not totally essential--information. We performed a retrospective analysis of physicians' ordering practices after introducing the absolute neutrophil count (ANC) as a stand-alone test in a hematology/oncology clinic. Previous studies have demonstrated a strong correlation between the ANC, as determined by the Coulter STKS instrument, and the manual neutrophil count. In contrast to the more extensive five-part differential the ANC is a one-part differential that focuses exclusively on the neutrophil count and provides abbreviated information. The hematology laboratory's records from 2 months before and 4 months after introducing this new test were analyzed. Total numbers of ANCs, automated complete differentials, and manual complete differentials performed were tabulated. After its introduction, the ANC comprised more than 75% of differentials performed in this clinic. Manual complete differentials dropped from 69.4% to 18.8%. The turnaround time (TAT) for all differentials taken together dropped by 75% (p = 0.042). We conclude that the ANC can be used widely in the hematology/oncology clinic as a separate, stand-alone test. For clinicians, its popularity over the five-part differential may be based on the fact that the ANC is a focused test with a relatively short TAT. Our experience suggests that it is the test result's relevance and not the volume of information provided that determines clinicians' use.