Suggested Rational Considerations for ANA-IF and ENA-Profile Test Requisition: Clinical Manifestation, Gender, Pattern, and Titer of ANA-IF

Yenny Surjawan (Prodia National Reference Laboratory, Jl. Kramat Raya No. 150, Jakarta 10430)
Umi Solekhah Intansari (Clinical Pathology Department, Faculty of Medicine, Public Health and Nursing, Universitas Gajah Mada, Jl. Farmako, Sekip Utara, Yogyakarta 55281)

The Indonesian Biomedical Journal
Vol 15, No 3 (2023)

BACKGROUND: The anti-nuclear antibody immunofluorescence (ANA-IF) test is used for screening of autoantibody presence in patients with suspected autoimmune disease. Positive ANA-IF should be followed-up with extractable nuclear antigens profile (ENA-profile). High ANA-IF sensitivity combined with low ENA-profile sensitivity, and the evolution of ANA-IF requests may result in a higher number of positive ANA-IF but negative ENA-profile. It is necessary to make an objective assessment in determining the conditions in which rational ANA-IF and ENA-profile should be suggested.METHODS: Data were retrieved retrospectively from the medical records of subjects who performed both ANA-IF and ENA-profile. ANA-IF were examined using immunofluorescence principle with cut-off 1:100. ENA-profile which contained sixteen purified antigens was performed using line-immunoblot principle. Data was analyzed descriptively and analytically using SPSS, and significant result was indicated if p<0.05.RESULTS: The ANA-IF result was dominated by negative (44.9%) and positive-speckled, titer 1:100 (32.9%). Of 923 subjects with positive ANA-IF, 45.4% had a negative ENA-profile. Of 751 subjects with negative ANA-IF, 10.2% had positive ENA-profile. In subjects whose specific clinical entity, the ANA-IF sensitivity and negative predictive value (NPV) in detecting ENA-profile were 93.8% and 93.3%, respectively, but the positive predictive value (PPV) was 63.2%. Women with specific autoimmune manifestation accompanied by ANA-IF homogeneous ≥1:100, or centromeres ≥1:100, or speckled ≥1:320 might have been predicted as subsequent positive ENA-profile with area under curve (AUC) of 77.2%, 76.9%, 79.2%, respectively.CONCLUSION: ANA-IF should only be indicated for those with specific clinical symptoms. For woman with typical symptoms, the presence of positive ANA-IF with homogeneous ≥1:100, or centromeres ≥1:100, or speckled ≥1:320 should be further followed-up by ENA-profile.KEYWORDS: ANA-IF, ENA-profile, autoimmune, autoantibody