       Document 0431
 DOCN  M9640431
 TI    Variability in leukocyte subset measurements among five laboratories in
       Vancouver.
 DT    9604
 AU    Mandigo K; Raboud JM; Haley L; Montaner JS; Canadian HIV Trials Network,
       Department of Health Care and; Epidemiology, Faculty of Medicine,
       University of British; Columbia, Vancouver.
 SO    Clin Invest Med. 1995 Oct;18(5):349-56. Unique Identifier : AIDSLINE
       MED/96120807
 AB    Cell counts and percentages of CD4 are widely used in the prognostic and
       clinical management of HIV-infected patients, and as surrogate outcomes
       in clinical trials involving HIV-infected individuals. Considerable
       variability in CD4 counts has been documented due to physiologic and
       methodologic factors. While studies of variability of CD4 counts among
       American and French laboratories have been reported in the literature,
       no published data are available for Canadian laboratories. This paper
       describes the results of a study to determine the variability of
       leukocyte subsets among 5 laboratories in Vancouver, British Columbia.
       Samples were collected in a prospective fashion from 52 HIV-negative
       patients from July 1991 to November 1993. Coefficients of variation (CV)
       were calculated for leukocyte subset percentages and absolute cell
       counts among laboratories. Our results demonstrate that the variability
       in leukocyte subsets among 5 Vancouver laboratories was lower than or
       comparable with published findings. The variability remained stable over
       the time period of the study, although 4 of the 5 laboratories
       participated in quality assurance programs. This suggests a plateau in
       the impact of this program. Since the variability among laboratories is
       less than the variability attributable to physiologic factors, further
       research efforts to reduce this variability should focus on physiologic
       sources.
 DE    British Columbia  Comparative Study  CD4 Lymphocyte Count  Human  HIV
       Infections/BLOOD  Laboratories/*STANDARDS  *Lymphocyte Count
       *Lymphocyte Subsets  Prospective Studies  Support, Non-U.S. Gov't
       JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

