Background: The tonsils and adenoids play a crucial role in the immune system, particularly during early childhood. Tonsillectomy is one of the most frequently performed surgical procedures in children.

Objectives: This study aimed to investigate the association between pediatric tonsillectomy and the subsequent development of autoimmune diseases.

Methods: Data from the Health Insurance Review and Assessment Service (HIRA) were analyzed to examine children aged 0–12 years who received medical care for tonsil or adenoid diseases between January 2007 and January 2008. Participants were divided into surgical (those who underwent tonsillectomy or adenoidectomy before June 2013) and non-surgical groups. The occurrence of autoimmune diseases was monitored until June 2023. Cox proportional hazards models were used to analyze the risk of autoimmune disease development.

Results: A total of 84,030 children in the surgical group and 336,120 age- and sex-matched children in the non-surgical group were analyzed. The mean age of the participants was 5.3 years. In the surgical group, the mean age at surgery was 7.6 years. The incidence rates of autoimmune diseases in the non-surgical and surgical groups were 65.3 and 86.5 per 100,000 person-years, respectively. Surgery (vs. non-surgery) was associated with an increased risk of developing systemic lupus erythematosus (HR 2.2, 95% CI 1.55–3.13), ankylosing spondylitis (HR 1.35, 95% CI 1.06–1.72), juvenile rheumatoid arthritis (HR 1.69, 95% CI 1.19–2.39), type 1 diabetes (HR 1.34, 95% CI 1.14–1.58), Hashimoto’s thyroiditis (HR 1.39, 95% CI 1.22–1.57), and Graves’ disease (HR 1.38, 95% CI 1.22–1.56). Overall, surgery was associated with an increased risk of autoimmune disease development (HR 1.32, 95% CI 1.23–1.41).

Conclusion: Tonsillectomy or adenoidectomy during childhood was associated with an increased risk of developing autoimmune diseases later in life. These findings suggest that the tonsils and adenoids may play a protective role in preventing the occurrence of autoimmune diseases.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.