Chemioluminescent microparticle immunoanalysis (CMIA) in the diagnosis of syphilis: characterization and assessment

Abstract

Background: The chemiluminescent microparticle immunoassay (CMIA) is not recommended for screening or confirmation of syphilis in patients, Chilean guidelines recommend screening with VDRL and confirmation with hemagglutination. Aim: To determine the specificity, sensitivity, and diagnostic correlation of this technique compared to the usual treponemal test. Methods: Of the 815 samples obtained over a period of 6 months, all of which were subjected to VDRL, MHA-TP, and CMIA testing, 484 samples were positive for MHA-TP. The performance was determined, ROC curves were graphed, correlation index and optimal cutoff point were determined. Results: CMIA showed a sensitivity of 100%, specificity of 94.6%, NPV of 100%, PPV of 96.4%, and an efficiency of 97.8%  compared to MHA-TP, with a correlation index of 0.97 and a cutoff point of 7.665, such that any sample with a CMIA value above this value would not require a second treponemal test for confirmation. 7.11% had intermediate CMIA values (1.0 to 7.664). Conclusion: CMIA is a highly sensitive and specific automated technique comparable to MHA-TP. When applied as an initial screening test for syphilis, it increases diagnostic certainty and may allow for early diagnosis of the disease.