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Abstract
Background Antinuclear antibodies (ANA) are autoantibodies that recognise cellular antigens found predominantly in the cell nucleus. They are associated with numerous autoimmune diseases.
ANA is routinely requested as part of an initial work-up for autoimmune conditions. In healthy children (5-18%), ANA titres of 1/80 to 1/320 have been reported. 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 first presentation could predict final diagnosis.
Methods A single centre (Great Ormond Street Hospital for Children), retrospective study. The immunology laboratory provided a list of positive ANA results (using indirect immunofluorescence technique). A retrospective chart review was performed to ascertain presence or absence 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 and grouped these into 11 categories.
Results A retrospective chart review was performed on 1354 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). 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 (figure 1). 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).
Conclusion This study suggests that, patients presenting with higher ANA titres and a combination of clinical features at presentation should be assessed systemically and followed-up as they may have increased risk of an autoimmune rheumatological diagnosis.