Background:
The diagnosis and treatment of many diseases characterized by the presence of eosinophilia depend on an accurate determination of the circulating eosinophils in the blood. Total eosionphil counts may be direct or indirect. The direct count
procedure
is performed using the hemacytometer. The indirect count includes calculated automatic method and determination from the differential count. This study was carried out to compare the direct and indirect techniques for the detection of circulating
eosinophils
Methods:
One hundred peripheral blood specimens were counted by three techniques; by total eosinophil count using hemacytometer(TEC), automated Coulter-STKS hematologic analyzer (ADC), and eosinophil percentage of microscopic differential count
multiplied by
WBC count from STKS(CEC). Correlation and agreement among three techniques were compared with one way analysis of variance, Pearson's correlation and intraclass correlation by SAS program. Precisions of three methods were also observed using
specimens
with normal, mildly increased, and markedly increased eosinophil count.
Results:
Eosinophil counts obtained by TEC, ADC, and CEC methods were similar in mean vzlues of 452/㎕, 541/㎕, and 520/㎕, respectively, demonstrating no significant difference(p=0.7906) among three methods. Correlation coefficients among three methods
were
all higher than above 0.98. Intraclass correlation coefficients(γ1) between ADC/CEC, ADC/TEC, and CEC/TEC are 0.9908, 0.9721, and 0.9778, respectively. On the basis of p and ㎕, interchangeability among three methods is evidenced. At the
level of
increased esoinophil count, three methods showed good precision(C.V : 2.4-14.9%)but in specimen with normal eosinophil count, ADC(C.V : 11.2%) was more precise than CEC(79.1%), and TEC(41.5%).
Conclusions:
There seems to be statistically allowable interchangeability among three methods, which makes it possible to replace conventional hemocytometer method with new methods using automated analyzer.
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