Optimizing pretransfusion antibody detection and identification: a parallel, blinded comparison of tube PEG, solid-phase, and automated methods.
BACKGROUND
The ideal pretransfusion testing strategy identifies maximal significant antibodies at minimal cost. Objectives of this study were to compare the characteristics of three testing methods and determine their optimal incorporation into the following generic testing sequence: 1) screen, for antibodies 2) if results are positive, use primary identification method, 3) if results are inconclusive, use secondary identification method.


METHODS
A total of 2000 consecutive, unselected, coded specimens were tested with three screening methods-PEG IAT, manual and automated solid phase red cell adherence assay (SPRCA). Of 202 positive results, 187 were of sufficient volume and were tested with both PEG and manual SPRCA identification panels, yielding 82 with significant antibodies, plus one that was negative by both methods found on retrospective review of nonstudy results. Calculations were made on the 1985 volume-sufficient specimens, simulating the possible testing permutations.


RESULTS
Manual SPRCA was the most sensitive antibody screen (67/83 = 81%) and the least specific (1840/1902 = 97%); automated SPRCA was the least sensitive (54/83 = 65%) and most specific (1883/1902 = 99%); and PEG was intermediate in both sensitivity (64/83 = 77%) and specificity (1860/1902 = 98%). Of the identification panels, manual SPRCA identified more antibodies than PEG (67 versus 66) but had more inconclusive results (41 versus 20). Of overall strategies, manual SPRCA screening with either sequence of identification methods identified the most antibodies (66). The combination of PEG screen, PEG identification, and manual SPRCA identification identified slightly fewer antibodies (63) but had the lowest reagent cost, total (reagent plus labor) cost, and cost per antibody identified. The sequence of automated SPRCA screening with manual SPRCA identification, and PEG identification had the lowest hands-on time.


CONCLUSIONS
The most cost-effective pretransfusion strategy is PEG screen with PEG identification, plus manual SPRCA identification when PEG identification is inconclusive.
Bunker
M L
ML
Department of Pathology and Laboratory Medicine, Western Pennsylvania Hospital, Pittsburgh, Pennsylvania 15224, USA. mbunker@wpahs.org
Thomas
C L
CL
Geyer
S J
SJ
D000906:Antibodies / Q000097:blood*; D001803:Blood Transfusion; D003362:Cost-Benefit Analysis; D006403:Hematologic Tests / Q000379:methods*; D006801:Humans
D000906:Antibodies