Abstract:

Objective To investigate the clinical roles of indirect immunofluorescence assay（IFA），line immunoassay（LIA） and chemiluminescent assay（CLIA） singly and in combination for determining antinuclear antibodies（ANA）. Methods Totally，4 722 patients who underwent ANA determination at Shanghai Ninth People's Hospital of Shanghai Jiao Tong University School of Medicine from August 2022 to July 2023 were enrolled，which included 935 patients with autoimmune diseases（AID） and 3 787 patients without AID. IFA was used to determine ANA，while LIA and CLIA were used to determine ANA specific spectra. The consistency analysis between different methods was conducted using Kappa test. The efficacy of different methods for diagnosing AID was evaluated by receiver operating characteristic（ROC） curve. Results The positive determination rates of IFA，LIA and CLIA in AID group were 67.5%，52.1% and 44.8%，respectively，which were all higher than those in non-AID group（36.9%，20.1% and 17.4%，respectively）（P<0.05）. The consistency between IFA and LIA was average（Kappa=0.609），while the consistency between IFA and CLIA was poor（Kappa=0.276）. Among patients with different types of diseases，AID patients had the highest consistency（Kappa values of 0.628 and 0.444 for IFA with LIA and CLIA，respectively），while patients with other diseases had the lowest consistency（Kappa values of 0.120 and 0.194 for IFA with LIA and CLIA，respectively）. The areas under curves（AUC） for diagnosing AID using IFA，LIA and CLIA single determinations were 0.707，0.662 and 0.655，respectively. The AUC of parallel determinations of IFA+LIA and IFA+CLIA were 0.711 and 0.699，respectively，and those of series determinations IFA+LIA and IFA+CLIA were 0.677 and 0.647，respectively. Conclusions The consistency between IFA and LIA or CLIA is not high，and inconsistent results are more likely to occur in non-AID patients. When using a single determination for AID screening，IFA should be prioritized. If ANA and ANA specific spectrum are used for combined determination，parallel determination should be preferred.

Key words: Antinuclear antibody, Indirect immunofluorescence assay, Line immunoassay, Chemiluminescent assay, Autoimmune disease