To Win the Battle, First Know Your Enemy: Error Rates in Immunohematology External Quality Assessment Results

Abstract

<b><i>Background:</i></b> As some errors in pretransfusion testing remain unrecognized, error rates and the resulting need for corrective measures are probably underestimated. External quality assessment (EQA) schemes could provide valuable input for identifying error-prone laboratory tests because they are designed to monitor test performance and errors. So far, however, there are only limited published data on error rates in such schemes. <b><i>Methods:</i></b> The types and incidence of incorrect results in an EQA scheme for red cell immunohematology with 187 participating laboratories were examined. The results of 58 distributions between 1999 and 2017 were evaluated, considering also the employed determination methods. <b><i>Results:</i></b> Out of a total of 58,726 results, 563 (0.96%) were incorrect. Error rates were 5.45% for antibody identification, 1.39% for Rh phenotyping, 0.83% for serologic cross-match, 0.60% for direct antiglobulin test, 0.20% for Kell phenotyping, 0.16% for antibody screening, and 0.14% for ABO phenotyping. During the observation period, 53 participants reported error-free results, while 37 reported one incorrect result and 97 repeatedly reported incorrect results for one or more analytes. Error rates obtained by manual methods significantly surpassed those obtained by automated methods (1.04 vs. 0.42%). The introduction of double testing with two different systems reduced error rates in Rh phenotyping from 1.55 to 0.50%. <b><i>Conclusion:</i></b> Risk assessment should consider that error rates in pretransfusion test results vary. These data delineate the error risk potential of individual laboratory tests and thus should aid in tailoring appropriate improvement measures.

Evaluation of Pre-Transfusion Crossmatch Test Using Microscanner C3

“…Out of a total of 58,726 results, 563 (0.96%) were incorrectly identified by the External Quality Assessment (EQA) conducted by the Austrian Association for Quality Assurance and Standardization of Medical and Diagnostic Tests. The error rate associated with the manual method was significantly higher than that of the automated method (1.04% vs. 0.42%) [ 37 ]. Additionally, while the conventional tube method allows for a semi-quantitative assessment of agglutination (−, ±, 1+, 2+, 3+, 4+), the Microscanner enables a quantitative evaluation of both the size and degree of agglutination.…”

Importance of Life-Long Alerts in Electronic Medical Report Systems for Patients With Positive Antigen Screening

“…These include an insufficient quantity of antibodies on RBCs, improper incubation temperature (including during transport to external laboratories), under-centrifugation, delay in adding Coombs reagent or adding expired Coombs reagent, incorrect quantity of Coombs reagent, improper antigen to antibody ratio, and elution of low-avidity antibodies from RBCs during washing [ 6 ]. Buchta et al showed that antibody screening produces 0.16% false-negative results [ 7 ].…”

Landsteinerʼs legacy: The continuing challenge to make transfusions safe

“…None of the FDAʼs ABOi RBC fatality cases involved automated testing. In an Austrian proficiency testing program, manual blood typing had twice as many errors as automated typing 51 . One loophole in automated testing is serologic ABO crossmatching, which is not approved on instruments in the United States.…”