Document 0681
 DOCN  M9620681
 TI    Variability in absolute lymphocyte counts obtained by automated cell
       counters.
 DT    9602
 AU    Simson E; Groner W; Department of Pathology, Long Island Jewish Medical
       Center, New; Hyde Park, NY 11040, USA.
 SO    Cytometry. 1995 Mar 15;22(1):26-34. Unique Identifier : AIDSLINE
       MED/96090279
 AB    There is increasing interest in the absolute lymphocyte count. This is
       partly driven by the need to obtain absolute values for lymphocyte
       subsets such as absolute CD4+ counts in human immunodeficiency virus
       (HIV)-infected persons. The absolute total lymphocyte count is usually
       determined in the routine hematology laboratory on a separate sample
       from the same patient specimen and then combined with percentage results
       from flow cytometry to obtain the absolute value of the lymphocyte
       subsets. We have studied analytic variability in the absolute lymphocyte
       determination and compared it to the variability of the total white
       blood count (WBC). In a series of 524 specimens, four different
       automated methods were compared to each other and to the traditional eye
       count differential. The automated methods were four widely used
       automated cell counters (Technicon H*1, TOA NE8000, Coulter STKS, and
       Abbott CD3000). The results indicate that analytic variability in the
       absolute lymphocyte counts, due, primarily, to method variability, is
       significant and is larger than the variability typically observed on
       interlaboratory trials of relative CD4 counts. These method biases
       cannot easily be reduced by calibration, since the cell classification
       algorithms are built-in features of the various cell counters. Analytic
       variability of the absolute lymphocyte counts was found to be 12.4%
       compared with analytic variability of only 4.9% for total WBC counts on
       the same samples. Our data suggest that more precise results would be
       obtained if flow cytometry results expressed each phenotype as a
       fraction of the leukocytes as well as total lymphocytes. Conversion to
       absolute values could then be accomplished through determination of the
       total WBC in the routine hematology laboratory.
 DE    Automation  CD4 Lymphocyte Count/*INSTRUMENTATION  Human
       Reproducibility of Results  Specimen Handling  CLINICAL TRIAL  JOURNAL
       ARTICLE  RANDOMIZED CONTROLLED TRIAL

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