Clinical usage of the leukocyte count in emergency room decision making.

Leukocyte (WBC) and differential counts are commonly used, but their clinical characteristics are poorly understood. To understand how the clinician interprets the WBC count in the presence of these uncertainties, the authors used a case vignette with a questionnaire to isolate physician reaction to an abnormal WBC count as compared with a normal control WBC count. In response to a case vignette of a urinary tract infection in the emergency room, physicians altered their diagnostic and therapeutic plans based solely on the WBC count. The results of the study also suggest that the cost of the WBC is not limited to the test cost, but also includes the cost of the physician reaction to the abnormal WBC count.