Abstract
BackgroundTo evaluate the interpretation and reporting of antinuclear antibodies (ANA) by indirect immunofluorescence assay (IFA) using HEp-2 substrates based on common practice and guidance by the International Consensus on ANA patterns (ICAP).MethodParticipants included two groups [16 clinical laboratories (CL) and 8 in vitro diagnostic manufacturers (IVD)] recruited via an email sent to the Association of Medical Laboratory Immunologists (AMLI) membership. Twelve (n = 12) pre-qualified specimens were distributed to participants for testing, interpretation and reporting HEp-2 IFA. Results obtained were analyzed for accuracy with the intended and consensus response for three main categorical patterns (nuclear, cytoplasmic and mitotic), common patterns and ICAP report nomenclatures. The distributions of antibody titers of specimens were also compared.ResultsLaboratories differed in the categorical patterns reported; 8 reporting all patterns, 3 reporting only nuclear patterns and 5 reporting nuclear patterns with various combinations of other patterns. For all participants, accuracy with the intended response for the categorical nuclear pattern was excellent at 99% [95% confidence interval (CI): 97–100%] compared to 78% [95% CI 67–88%] for the cytoplasmic, and 93% [95% CI 86%–100%] for mitotic patterns. The accuracy was 13% greater for the common nomenclature [87%, 95% CI 82–90%] compared to the ICAP nomenclature [74%, 95% CI 68–79%] for all participants. Participants reporting all three main categories demonstrated better performances compared to those reporting 2 or less categorical patterns. The average accuracies varied between participant groups, however, with the lowest and most variable performances for cytoplasmic pattern specimens. The reported titers for all specimens varied, with the least variability for nuclear patterns and most titer variability associated with cytoplasmic patterns.ConclusionsOur study demonstrated significant accuracy for all participants in identifying the categorical nuclear staining as well as traditional pattern assignments for nuclear patterns. However, there was less consistency in reporting cytoplasmic and mitotic patterns, with implications for assigning competencies and training for clinical laboratory personnel.
Highlights
The presence of antinuclear antibodies (ANA) is a hallmark and classification criterion for a number of systemic autoimmune rheumatic diseases (SARD)
Laboratories differed in the categorical patterns reported; 8 reporting all patterns, 3 reporting only nuclear patterns and 5 reporting nuclear patterns with various combinations of other patterns
Accuracy with the intended response for the categorical nuclear pattern was excellent at 99% [95% confidence interval (CI): 97–100%] compared to 78% [95% CI 67–88%] for the cytoplasmic, and 93% [95% CI 86%–100%] for mitotic patterns
Summary
The presence of antinuclear antibodies (ANA) is a hallmark and classification criterion for a number of systemic autoimmune rheumatic diseases (SARD). The indirect immunofluorescence antibody (IFA) technique on HEp-2 substrate has been considered the traditional and preferred method for detecting ANA by some [1]. The recognition of a well-defined HEp-2 IFA staining pattern may be helpful in determining the most likely specific autoantibodies present, as well as suggesting possible clinical associations for known specificities [3, 4]. In this regard, a positive HEp-2 IFA screening pattern can guide confirmatory testing and may be useful for elucidating a specific clinical diagnosis or prognosis. To evaluate the interpretation and reporting of antinuclear antibodies (ANA) by indirect immunofluorescence assay (IFA) using HEp-2 substrates based on common practice and guidance by the International Consensus on ANA patterns (ICAP)
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