EOSINOPHILIA DETECTED BY AUTOMATED BLOOD-CELL COUNTING IN AMBULATORY NORTH-AMERICAN OUTPATIENTS - INCIDENCE AND CLINICAL-SIGNIFICANCE

Objectives.-To audit a cohort of ambulatory outpatients with eosinophi lia detected on automated blood cell counting. Specific objectives inc luded the determination of whether the eosinophilia had been anticipat ed, the etiology of the eosinophilia, the clinical follow-up and inves tigations performed on patients with eosinophilia, and the effect of t he detection of eosinophilia on patient management and ultimate clinic al outcome. Design.-A year-long retrospective review of all patients w ith an absolute eosinophil count of greater than 0.7 x 10(9)/L. Settin g.-A large outpatient laboratory system. The patient population was ma naged by family physicians and specialists. Intervention.-Data collect ion included the results of the hematology profile, the absolute eosin ophil count, the clinical situation responsible for the hematologic pr ofile determination, and the probable cause of eosinophilia. Individua l physicians were surveyed to determine if discovery of the eosinophil ia had changed patient management plan or clinical outcome. Principal Results.-Out of 195 300 patients who had a hematology profile performe d, 225 were found to have an absolute eosinophilia count higher than 0 .7 x 109/L. The overall incidence of eosinophilia in the study populat ion was 0.1%. The eosinophilia was not anticipated in 85% of patients. No obvious cause was detected for the eosinophilia in 36% of patients . Various allergic diseases were responsible for the eosinophilia in t he majority of the remaining patients. Fewer than 9% of individuals ma nifested a serious systemic illness or parasitemia. Further clinical f ollow-up had been performed in 69% of patients. Additional laboratory tests had been ordered in 59% of patients. The laboratory tests most f requently ordered were a repeat hematology profile or stool examinatio ns for ova and parasites. In only two instances did the discovery of t he eosinophilia appear to result in a significant change in patient ma nagement or ultimate clinical income. Conclusion.-The vast majority of eosinophilias detected in ambulatory outpatients are associated with allergic processes. An extensive investigation of eosinophilia in ambu latory North American outpatients does not appear to be warranted unle ss specifically indicated by the results of the history and physical e xamination.