Weak D testing might be discontinued for RhD-negative blood donors with C and E negative phenotypes in the Indian population.

Background: Although serological testing to determine weak D status using the antihuman globulin reagent has been phased out for RhD-negative donors in many countries after the availability of RHD genotyping, it is routinely performed in India. However, weak D testing is a resource-intensive and time-consuming process. We devised a new algorithm for weak D testing in RhD-negative blood donors by performing CcEe phenotyping followed by weak D testing in only C+ and/or E + samples and compared it with the existing protocol in terms of time and cost-effectiveness.

Method: In this observational study, we tested 500 samples of RhD-negative blood donors over one year in India. The existing and new algorithms were compared, and the agreement was calculated in terms of the test results, time required for testing, and total cost involved. The RhD type, weak D status, and CcEe phenotypes were determined using the conventional tube technique. An adsorption-elution test was performed to check for the Del phenotype. We conducted RHD genotyping for all samples negative for weak D testing.

Results: The proposed algorithm showed perfect agreement with the existing protocol (agreement = 100 %; κ= 1.00). By applying the new algorithm, we could reduce 71.63 % of testing time and 24 % of total cost without missing any weak D positive samples in blood donors.

Conclusions: Weak D testing might be discontinued for RhD-negative blood donors with C and E negative phenotypes in the Indian population and could be restricted to only C+ and/or E + phenotypes, which seems to be a time- and cost-effective testing strategy.