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

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.

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.

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.

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.

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.