Autoimmune Thyroid Disease in Primary Sjögren's Syndrome: Real-life Screening Practice and Clinical Outcomes.

Background: Notwithstanding the frequent coexistence of autoimmune thyroid disease (ATD) and primary Sjögren's Syndrome (SS), it is still unknown how often this association is studied along with its clinical impact.

Objective: This study aimed to describe real-world screening practices for ATD in patients with SS and evaluate clinical outcomes of patients with both diagnoses using validated activity and chronicity indexes.

Methods: It is a retrospective study of 223 patients with SS attending a tertiary referral center. Patients were under rheumatology surveillance and might have attended other clinics, including internal medicine and/or endocrinology. We registered glandular and extraglandular features, serology and scored the activity (ESSDAI) and the accrual damage (SSDDI) indexes. We also identified any thyroid function tests (TFT) performed, anti-thyroid antibodies, images, and histological thyroid examinations. A single endocrinologist reviewed all data.

Results: One hundred forty-nine patients had at least one set of TFT. Younger age was associated with a lack of screening (OR 0.98, 95 % CI 0.95-0.99, p=0.01). Sixty-nine patients had thyroid disease, with the most common diagnosis being ATD (n=24). Patients with ATD had a lower prevalence of Ro/SSA and anti-La/SSB antibodies but similar cumulative SS activity and damage scores.

Conclusion: At least one-third of our patients were not screened for thyroid disease, with these patients being the youngest. Thyroid disorders were found in about 40 % of patients with SS, with ATD being the most common. Having SS/ATD did not confer more disease activity or damage accrual. These results highlight the importance of making treating physicians aware of screening for thyroid disease in this population.