A retrospective cohort study published in the British Journal of Haematology has shown children with primary immune thrombocytopenia (ITP), who also have high-titre antinuclear antibody levels, may be at greater risk of autoimmune disease development relative to those without it.
ITP is a haematological disease characterized by isolated thrombocytopenia due to the increased destruction of platelets or impaired platelet production, the researchers noted. Although ITP pathogenesis remains unclear, immune dysfunction plays a key role in the occurrence and development of ITP, they added.
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Antinuclear antibody (ANA) refers to the antibodies class directed at material within the cell nucleus, the study authors noted. Prior studies have reported that a positive ANA can be detected in children with primary ITP, with a prevalence of 9.04% to 44%; however, the association between positive ANA and the prognosis of primary ITP in children without consensus is not reported to date, they continued.
This single-center study involved children with primary ITP and was conducted at the Peking Union Medical College Hospital in China. They followed 324 children with primary ITP for a median time of 25 months. The inclusion criteria for patients were based on several factors, including those with platelet count less than 100 × 109/l measured on multiple occasions at least 7 days apart and those aged 18 years of age or younger.
The diagnosis and management of primary ITP patients were based on the International Consensus Report on the investigation and management of primary ITP. The patients were divided into subgroups based on the highest ANA titre. Of the 324 children, 127 (39.2%) were found in the ANA titre of 1:160 or higher group, and 197 (60.8%) children were in the ANA titre less than 1:160 group.
Study results revealed that patients with higher ANA titres had lower platelet counts at the onset. However, they had a greater recovery rate of subsequent platelet counts. Moreover, 51 (40.2%) patients in the ANA titre 1:160 or higher group and 11 (5.6%) patients in the ANA titre below 1:160 group developed to AIDs, suggesting that patients with ANA titres of 1:160 or more were more likely to develop AID compared to those without, and the risk of AID development increased with the rise of ANA titres.
“These data highlight the predictive value of ANA titre for platelet counts and the risk of AID development in children with primary ITP,” the authors highlighted.
The authors acknowledged several limitations in the study including the single-centre, retrospective study design, the data availability on platelet autoantibodies, lack of proof on the relationship between the platelet autoantibodies level and ANA titres and the lack of certain information on some patients which presented a potential bias.
Liu J, Zhang Y, Li Z, et al. The effect of antinuclear antibody titre and its variation on outcomes in children with primary immune thrombocytopenia. Br J Haematol. Published online Mar 17, 2023. doi: 10.1111/bjh.18732