The use of the differential leukocyte count for inpatient casefinding.

The differential leukocyte count is a nonspecific, imprecise, error-prone, usually labor-intensive, and expensive test to perform. Although the differential count is frequently ordered in the absence of clinical suspicion in both inpatient and outpatient settings, its effectiveness as a screening test has been studied little. From a detailed chart review of 287 cases randomly drawn from a population of 2682 adult patients for whom a differential count was performed on admission, we found that 23 per cent of the cases met criteria for admission screening, that abnormal results were found in approximately one half of these screening differential examinations, and that one third of the abnormal examinations were acknowledged in the medical record by a physician. In no instance did a screening differential count appear to have had clinical significance. It may be medically prudent to consider discontinuing the differential leukocyte count as an inpatient screening test for adults.