P24 Can high ANA titre combined with clinical features predict developing autoimmune conditions in children?
Authors: Cinar Ovgu Kul , Foley Charlene , Al-Hussaini Ali , Gilmour Kimberly , Buckland Matthew , Al-Obaidi Muthana 
Published: October 2019

Poster presentation Tuesday 8 October

Background
Antinuclear antibodies (ANA) are autoantibodies that recognise cellular antigens found predominantly in the cell nucleus. They are associated with numerous autoimmune diseases such as systemic lupus erythematosus, but may also be found in infectious diseases, malignancies and healthy individuals.
ANA is requested as part of an initial work-up for autoimmune conditions. In healthy children (5-18%), positive ANA titres of 1/80 to 1/320 have been reported. A prospective study of healthy children with positive ANA found that children who developed autoimmune disease had clinical features at presentation that were suspicious for such an outcome. Therefore, the usefulness of a positive ANA result for diagnosing autoimmune conditions is limited without clinical correlation. The aim of our study was to assess whether high ANA titre and clinical features at presentation could predict final diagnosis.

Methods
Single centre retrospective study at Great Ormond Street Hospital for Children (GOSH). The immunology laboratory provided a list of positive ANA results (using indirect immunofluorescence technique) from January 2013 to July 2018. A retrospective chart review was performed to ascertain presence of clinical features at presentation under the five following titles: arthritis, skin involvement, eyes, CNS involvement and Raynaud’s phenomenon. We then reviewed the last clinical contact to document confirmed diagnosis.

Results
We performed a retrospective chart review on 1,354 children (67% female; median age 7.5 years (0.1-17.5); median follow-up 4.8 years (0-18)) with positive ANA results (titres 1/160, 1/320, 1/640, 1/1280, 1/2560 and >1/2560). Table 1 reports ANA titres at first presentation in relation to final diagnosis. A titre of 1/640 or above was most commonly seen (>50%) in children with an autoimmune rheumatology condition. In fact, children with the highest titre (>1:2560) were significantly more likely to be diagnosed with one of these conditions. Finally, we looked at the number of presenting features and correlated with final diagnosis. Those diagnosed with a CTD were most likely to present with 2-5 clinical features (p < 0.0001).
P24 Table 1: Percentage of patients grouped according to their diagnosis and ANA titres Final Diagnoses ANA Titres >1: 2560 1: 2560 1: 1280 1: 640 1: 320 1: 160 Connective Tissue Diseases 24% 9% 13% 16% 16% 22% JIA and Uveitis 8% 11% 15% 22% 22% 22% JIA 6% 8% 13% 24% 24% 25% Autoimmune (other) 4% 5% 11% 19% 32% 29% Unidentified autoimmune/ autoinflammatory 8% 12% - 24% 12% 44% Vasculitis - - 5% 26% 16% 53% Sarcoidosis - 20% - 20% - 60% Autoinflammatory 7% - - 43% - 50% Malignancy - - - 25% - 75% Other 3% 2% 3% 17% 28% 47% Non-inflammatory MSK 3% - 9% 18% 27% 43%
Conclusion
This study suggests that, patients presenting with higher ANA titres and a combination of clinical features should be assessed systemically and followed-up as they may have increased risk of developing an autoimmune rheumatological conditions.

Conflicts of Interest
The authors declare no conflicts of interest.