Antinuclear antibody titre and its dynamics predict autoimmune disease progression in adults with immune thrombocytopenia.

OBJECTIVE: Antinuclear antibody (ANA) is frequently detected in patients with primary immune thrombocytopenia (ITP), but its prognostic value for subsequent autoimmune disease (AID) development remains unclear. This study aimed to evaluate the association between baseline ANA titre, its longitudinal dynamics and disease outcomes in adults with primary ITP. METHODS: We conducted a single-centre retrospective cohort study of 261 adults with primary ITP. ANA was tested at baseline and during follow-up. Generalised estimating equation (GEE) models and Cox regression were used to assess the associations between ANA titre and platelet counts, and between ANA titre and AID development. RESULTS: Over a median follow-up of 15 months, 23.75% had baseline ANA > 1:100. Higher ANA titres were significantly associated with lower platelet counts (global p = 0.002), particularly in 1:160 and 1:320 subgroups. Patients with ANA > 1:100 had significantly lower AID-free survival than those with ≤ 1:100 (log-rank p = 0.014). Dynamic ANA changes further stratified AID risk: rising (HR 7.159), persistently high (HR 3.515) and falling ANA (HR 3.598) all predicted higher risk versus consistently negative ANA (p = 0.035). CONCLUSIONS: Baseline ANA titre predicts lower platelet counts and higher AID risk in primary ITP. Serial ANA monitoring provides additional prognostic value, with rising or persistently high titres identifying patients at highest risk. ANA testing may aid in risk stratification and early AID detection. Key Points • Baseline ANA titre is significantly associated with lower platelet counts and higher risk of subsequent autoimmune disease in primary ITP. • Serial ANA monitoring provides additional prognostic value, with rising or persistently high titres identifying patients at greatest risk of autoimmune disease progression. • Dynamic changes in ANA titre (rising, persistent, or falling) all predict higher autoimmune disease risk compared with consistently negative ANA. • ANA testing and serial monitoring may facilitate risk stratification and early detection of autoimmune disease in patients with primary ITP.