Background/Purpose:   Notwithstanding the reported coexistence of autoimmune thyroid disease (ATD) and primary Sjögren’s syndrome (pSS), it is unknown if this association is routinely searched and how it influences the SS phenotype. We aimed to describe the proportion of patients with pSS who has been screened for thyroid disease, the prevalence of ATD and its impact in pSS phenotype in a single tertiary center cohort.

Methods:  We retrospectively reviewed the medical charts of 223 consecutive patients (1996-2016) with the diagnosis of pSS according to the AECG criteria. We registered demographics, glandular and extraglandular features, Schirmer-I test, non-stimulated whole salivary flow (NSWSF), ocular staining, serology (anti-Ro/SSA, anti-La/SSA, rheumatoid factor (RF), low C3 ever, low C4 ever, and hyperglobulinemia ever); as well as thyroid function tests (TFT), thyroid disease diagnosis, anti-thyroglobulin and anti-thyroid peroxidase antibodies and thyroid image studies. We scored the cumulative activity with the ESSDAI and damage accrual with the SSDDI at the end of follow-up.

Results:  149 patients (66.8%) had at least a set of TFT, these patients were older and had a longer disease duration than patients without a TFT assessment. Their mean age was 59.7±14.9 years, 95.2% female and median disease duration 10.4 years. Sixty-four of them (42.9%) had thyroid disease, being the main cause ATD in 24 patients (37.5%, CI 95% 27-50; 16 hypothyroidism and 8 hyperthyroidism). Other causes were non-autoimmune hypothyroidism (n=8, 12.5%), multinodular goiter (n=6, 9.3%), coloid goiter (n=4, 6%) and single thyroid nodule (one patient, 1%). We excluded for further analysis a group of 21 patients with hypothyroidism who lacked of anti-thyroid antibodies determination. When we compared patients with ATD (n=24) vs. without ATD (n=104) we did not find differences regarding the age, gender, disease duration, Schirmer-I test, impaired NSWSF, ocular staining, use of immunosuppressors, RF, low complement and hyperglobulinemia; as well as in the glandular and extraglandular features and cumulative ESSDAI (9.04±7.6 vs 11.4±8.9, p=0.19). However ATD patients had a lower prevalence of anti-Ro/SSA (58.3% vs. 88.3%, p=0.001) and anti-La/SSB antibodies (25% vs. 60.6%, p=0.002) than patients without ATD; as well as a lower SSDDI score (2.17±1.2 vs 2.77±2, p=0.05). At the logistic regression analysis, only anti-Ro/SSA and anti-La/SSB remained significant, conferring protection to ATD (OR 0.29, 95% CI 0.10-0.88, p=0.002 and OR 0.31, 95% CI 0.10-0.92, p=0.03, respectively).

Conclusion: Around one third of pSS patients were not evaluated for thyroid disease, and among those evaluated, 37.5% had ATD. These patients had a similar clinical prognosis than those without ATD, but were characterized by a lower prevalence of anti-Ro/SSA and anti-La/SSB antibodies.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-thyroid-autoimmune-disease-in-primary-sjogrens-syndrome-and-its-association-with-disease-phenotype/