Evaluation of the Coulter MAXM in a children's hospital.

An evaluation of the WBC differential given by the analyzer Coulter MAXM was performed in a children's hospital, in order to establish optimal interpretation of the automated MAXM report in pediatrics. The patient group comprised 419 children of age up to 15 years. Assessment was carried out by comparison of the MAXM results with microscopic examination of blood smears, good correlation being observed between the two methods in non flagged samples and those flagged only with an isolated "Imm Grans/Bands 1" message indicating the presence of band cells. Comparison of the MAXM and optical differentials in normal and abnormal samples was performed according to a standard protocol taking into account both suspect flags and quantitative abnormalities defined in relation to age. In this group of 419 children, there were 20 (4.8%) false positive and 8 (1.9%) false negative reports, the 8 false negative results corresponding to either minor morphological (4) or borderline quantitative abnormalities (4). Overall, the instrument was capable of detecting significant abnormalities in blood samples with a sensitivity of 95.5% and a specificity of 91.7%. Although the review rate was 45.3%, the high efficiency (93.3%) suggested that most blood smear reviews led to the discovery of a morphological and/or quantitative abnormality. Furthermore, the review rate was greater in neonates (< 7 days) and infants (7 days-1 year) but closer to those of adult populations in older children. The Coulter MAXM was thus shown to be appropriate for use in pediatrics, despite a higher frequency of blood smear review than in adults, particularly among patients less than one year old.