Diagnostic discrepancies: A retrospective analysis of two antinuclear antibody platforms

To retrospectively examine the outcome of the antinuclear antibody (ANA) screen by comparing the performance of BioPlex 2200 and immunofluorescence assay (IFA). We reviewed the ANA screening results performed on the BioPlex 2200 using multi-bead technology and the IFA using HEp-2 cells. The study encompassed 133 patients, comprising 111 females and 22 males. The average age of lupus patients at the time of diagnosis was approximately 53 years. Among 133 cases tested, 58 were negative, and 75 were positive on the BioPlex. 47% (27 out of 58 negative cases) of the tests performed with a negative result on BioPlex yielded positive results on the IFA. Conversely, 55% (41 out of 75 positive cases) of the multiplex-positive results were negative on the IFA. There were significant discrepancies in double-stranded DNA (27%) and RNP antibodies (51%), where multiplex-positive results turned negative on IFA. The findings reveal a notable disparity between the results of the BioPlex and IFA tests. This challenges the prevailing notion of IFA as the gold standard. Manufacturers should prioritize optimizing assays to minimize variability, while clinicians should consider the ANA results and the patient's clinical history and symptoms when interpreting the findings.