Ann Lab Med 2018; 38(6): 585-590
Weak D Testing is not Required for D- Patients With C-E- Phenotype
Sooin Choi, M.D.1*, Sejong Chun, M.D.2*, Hwan Tae Lee, M.D.3, HongBi Yu, B.S.4, Ji Young Seo, M.T.1, and Duck Cho, M.D.1,4
1Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; 2Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea; 3Department of Laboratory Medicine Gachon University Gil Medical Center, Incheon, Korea; 4Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, Korea
Corresponding author: Duck Cho
Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea
Tel: +82-2-3410-2403
Fax +82-2-3410-2719
* These authors contributed equally to this work.
Received: November 7, 2017; Revised: December 27, 2017; Accepted: May 30, 2018; Published online: November 1, 2018.
© Korean Society for Laboratory Medicine. All rights reserved.

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Background: Although testing to detect weak D antigens using the antihuman globulin reagent is not required for D- patients in many countries, it is routinely performed in Korea. However, weak D testing can be omitted in D- patients with a C-E- phenotype as this indicates complete deletion of the RHD gene, except in rare cases. We designed a new algorithm for weak D testing, which consisted of RhCE phenotyping followed by weak D testing in C+ or E+ samples, and compared it with the current algorithm with respect to time and cost-effectiveness.
Methods: In this retrospective study, 74,889 test results from January to July 2017 in a tertiary hospital in Korea were analyzed. Agreement between the current and proposed algorithms was evaluated, and total number of tests, time required for testing, and test costs were compared. With both algorithms, RHD genotyping was conducted for samples that were C+ or E+ and negative for weak D testing.
Results: The algorithms showed perfect agreement (agreement=100%; κ=1.00). By applying the proposed algorithm, 29.56% (115/389 tests/yr) of tests could be omitted, time required for testing could be reduced by 36% (8,672/24,084 min/yr), and the test cost could be reduced by 16.53% (536.11/3,241.08 USD/yr).
Conclusions: Our algorithm omitting weak D testing in D- patients with C-E- phenotype may be a cost-effective testing strategy in Korea.
Keywords: C-E- phenotype, Weak D testing, RHD genotyping, RhD blood type, Algorithm, D typing, Cost effectiveness, Testing time

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