Association between autoimmune thyroiditis and rheumatoid arthritis: a cross-sectional risk stratification study

Area of Science:

• Immunology
• Endocrinology
• Rheumatology

Background:

• Autoimmune thyroiditis (AIT) often co-occurs with other autoimmune conditions, suggesting shared mechanisms.
• Limited large-scale data exist on the AIT-rheumatoid arthritis (RA) link and potential mediating factors.

Purpose of the Study:

• To investigate the association between AIT and RA.
• To explore metabolic and endocrine mediators, specifically uric acid and free triiodothyronine (FT3), in this relationship.
• To develop and validate a risk stratification model for RA in AIT patients.

Main Methods:

• Cross-sectional analysis of US nationally representative data (NHANES 2007-2012).
• Multivariable logistic regression and mediation analyses for AIT-RA association and mediator effects.
• External validation of a risk model in a Chinese clinical cohort.

Main Results:

• AIT was significantly associated with prevalent RA in the NHANES cohort.
• Uric acid and FT3 showed statistical links to both AIT and RA.
• Uric acid partially mediated the AIT-RA association (13.4% in NHANES), with consistent external findings; FT3 mediation was inconsistent.
• The RA risk model demonstrated good discriminative performance (AUC 0.776 in NHANES, 0.724 externally).

Conclusions:

• AIT is associated with prevalent RA, with potential shared metabolic and endocrine underpinnings.
• Uric acid emerged as a potential mediator, while FT3's role was less clear.
• Findings support further longitudinal studies on thyroid and joint autoimmunity.