@article{42166a74ae7e41e9ac334c57913fb82b,
title = "Comparability of absolute/percent CD4+ T-lymphocytes completed locally and centrally",
abstract = "The Hemophilia Growth and Development Study (HGDS) is a multicenter longitudinal study of 333 male children and adolescents with moderate or severe hemophilia, ranging in age from 6 to 19 at entry. Sixty-two percent of the cohort was infected with human immunodeficiency virus (HIV) in the late 1970s and early 1980s through exposure to contaminated clotting factor concentrates. The HGDS has followed this cohort since 1989. HGDS subjects have blood drawn twice each year for t-lymphocyte subsets, with fresh blood shipped overnight to a central laboratory. T-lymphocyte subsets from the same blood draw are often determined locally as well. To evaluate interlaboratory variation, we examined the comparability of pairs of local and central results for CD4+ absolute counts and percents. Ninety-four pairs of absolute counts and 73 pairs of percent CD4+ results were available. We calculated concordance correlation coefficients, which evaluate the agreement between two readings from the sample by measuring the variation from the 45°line through the origin. Absolute counts were square root transformed. Comparability of the pairs was high for both absolute counts and percents (0.93 and 0.92, respectively). Agreement was high whether we determined the CD4+ counts and percents centrally, using fresh samples received the day after the examination (0.95, 0.95), or from specimens that were frozen upon receipt and batched for later testing (0.90, 0.87). We conclude that when a centrally processed CD4+ result is unavailable because of shipping problems or loss of specimens, a study may reasonably accept a CD4+ result completed locally, if validity checks indicate good comparability. In the HGDS, the data provided by the local laboratories were of comparable quality to those provided by the central laboratories. Copyright (C) 1998 Elsevier Science Inc.",
keywords = "CD4+ comparability, Central laboratory, Interlaboratory variation",
author = "Donfield, {Sharyne M.} and Mahoney, {Elizabeth M.} and Maeder, {Margaret A.} and Hawk, {Sarah M.} and Sirois, {Patricia A.} and Pearson, {Sunny K.} and Goldberg, {Ilene A.} and Richard, {Sharon K.} and Baird-Cox, {Kelly A.} and Hoel, {Lauren N.} and Cool, {Valerie A.}",
note = "Funding Information: We thank the children, adolescents, and parents who volunteered to participate in this study. We wish to acknowledge the contributions to the data used in this analysis made by Ms. Bonnie Jones and Dr. Steven McDougal of the Centers for Disease Control and Prevention, Ms. Gina Hamlin-Green of the National Cancer Institute, and Dr. Dean Mann of the University of Maryland. Supported by the Bureau of Maternal and Child Health and Resources Development (MCJ-060570), the National Institute of Child Health and Human Development (NO1-HD-4-3200), the Centers for Disease Control and Prevention, the Laboratory of Genomic Diversity of the National Cancer Institute, and the National Institute of Mental Health. Additional support was provided by grants from the National Center for Research Resources of the National Institutes of Health to the New York Hospital–Cornell Medical Center Clinical Research Center (MO1-RR06020), the Mount Sinai General Clinical Research Center, New York (MO1-RR00071), the University of Iowa Clinical Research Center (MO1-RR00059), and the University of Texas Health Science Center, Houston (MO1-RR02558). The Hemophilia Growth and Development Study is funded by the following: National Institutes of Health, National Institute of Child Health and Human Development; Bureau of Maternal and Child Health and Resources Development; Centers for Disease Control and Prevention; National Cancer Institute; National Institute of Mental Health. The following persons are the Center Directors, Study Coordinators, or Committee Chairs of the study: Childrens Hospital Los Angeles, E. Gomperts, MD, F. Kaufman, MD, M. Nelson, MD, S. Pearson, RN; The New York Hospital–Cornell Medical Center, M. Hilgartner, MD, S. Cunningham-Rundles, PhD, I. Goldberg, RN; University of Texas Medical School, Houston, W.K. Hoots, MD, K. Loveland, PhD, M. Cantini, RN; The National Institutes of Health, The National Institute of Child Health and Human Development, A. Willoughby, MD, MPH; New England Research Institutes, Inc., S. McKinlay, PhD, M.A. Maeder, MHS; Rho, Inc., S. Donfield, PhD; Baylor College of Medicine, C. Contant, Jr., PhD; University of Iowa Hospitals and Clinics, C.T. Kisker, MD, J. Stehbens, PhD, S. O{\textquoteright}Conner, J. McKillip; Tulane University Medical Center, P. Sirois, PhD; Children{\textquoteright}s Hospital of Oklahoma, C. Sexauer, MD, H. Huszti, PhD, F. Kiplinger, S. Hawk, PA-C; Mount Sinai Medical Center, S. Arkin, MD, A. Forster, RN; University of Nebraska Medical Center, S. Swindells, MD, S. Richard; University of Texas Health Science Center, San Antonio, J. Mangos, MD, A. Scott, PhD, R. Davis, RN; Children{\textquoteright}s Hospital of Michigan, J. Lusher, MD, I. Warrier, MD, K. Baird-Cox, RN, MSN; Milton S. Hershey Medical Center, M.E. Eyster, MD, D. Ungar, MD, S. Neagley, RN, MA; Indiana Hemophilia and Thrombosis Center, A. Shapiro, MD, J. Morris, PNP; University of California–San Diego Medical Center, G. Davignon, MD, P. Mollen, RN; Kansas City School of Medicine, Children{\textquoteright}s Mercy Hospital, B. Wicklund, MD, A. Mehrhof, RN, MSN.",
year = "1998",
month = oct,
doi = "10.1016/S0197-2456(98)00035-X",
language = "English (US)",
volume = "19",
pages = "451--460",
journal = "Controlled Clinical Trials",
issn = "0197-2456",
publisher = "Elsevier BV",
number = "5",
}