The discrepancy between manual and computerized leukocyte and thrombocyte counts

Abstract

Background Discrepancy between results of leukocyte and throm-
bocyte count by computerized and manual examination may exist
Objective To determine the discrepancy between computerized
and manual leukocyte and thrombocyte count.
Methods The design was a randomized sampling cross sectional
study. The blood sample was examined with computerized Cell
Dyn 1400 instrument for the leukocyte and thrombocyte count. For
manual examination, blood smear was performed to measure
thrombocyte while leukocyte was measured in Improved Neubauer
hemocytometer. The results of computerized examination were
used as gold standard. Sensitivity, specificity, predictive values of
manual count were calculated. The agreement of Kappa and Mc
Nemar test were determined
Results Blood specimens drawn from 100 patients with different
kinds of diagnoses were examined using computerized and manual
methods. In computerized group, 66% had normal leukocyte and
55% had normal thrombocyte count. In the manual group, 78% of
subjects had normal leukocyte and 82% had normal thrombocyte
count. From leukocyte examination, the sensitivity of manual count
was 87.9%, specificity was 41.2%, and positive predictive value
was 74.36 with the agreement of Kappa of 0.32 and Mc Nemar
value of 0.036. From thrombocyte examination, the sensitivity was
96.4%, specificity was 35.6%, and positive predictive value was
64.6 with the agreement of Kappa of 0.41 and Mc Nemar value of
0.41.
Conclusion The result of manual thrombocyte count was in ac-
cordance with computerized with the agreement of Kappa of 0.41.
On the other hand, there was a discrepancy between manual in
favor of computerized leukocyte count with the agreement of Kappa
of 0.32