Juvenile recurrent parotitis and risk of autoimmune disease: A 30-year nationwide cohort study.

BACKGROUND: Research on pediatric salivary gland diseases and autoimmune disease is limited. This study examines juvenile recurrent parotitis (JRP) and autoimmune diseases. OBJECTIVE: To examine associations between JRP and autoimmune diseases, and modification by sex and age. RESEARCH DESIGN AND METHODS: Danish nationwide cohort study of children with JRP identified through hospital contacts, 1994-2024, matching ten controls per case. We investigated ten autoimmune groups within Gastrointestinal disease, Vasculitis, Skin disease, Nervous system disease, Metabolic disease, Type I diabetes, Joint disease, Sjögrens disease, Hematologic disease, and Connective tissue disease. Cumulative risks were estimated using the Aalen-Johansen estimator and hazard ratios (HRs) using Cox proportional hazards regression. RESULTS: We identified 2915 cases and 29,140 controls. Among cases, 55.8% were male; median age was 8 years. The cumulative risk of autoimmune disease was 4.73% (95% CI 3.71-5.74) in JRP, and 3.02% (2.76-3.28) in controls. JRP was associated with autoimmune diseases (HR 1.71, 95% CI 1.37; 2.13), including Sjögrens disease (HR 28.16, 95% CI 10.14; 78.18), connective tissue diseases (HR 3.69, 95% CI 1.85; 7.36), and gastrointestinal diseases (HR 1.55,95% CI 1.07; 2.25). Associations were stronger in females (HR 1.86, 95% CI 1.40; 2.46) than males (HR 1.53, 95% CI 1.07; 2.18), significant among age 10-17 years (HR 2.22, 95% CI 1.65; 2.99). CONCLUSIONS: Nonspecific salivary gland disease, likely JRP, was associated with autoimmune diseases, including Sjögren's disease, connective tissue diseases, and gastrointestinal diseases. Associations were strongest in females and adolescents and may represent both increased risk and an early indicator of autoimmune disease.