Hashimoto Thyroiditis Increases Risk for New-Onset Systemic Lupus Erythematosus

The finding that Hashimoto thyroiditis is associated with subsequent systemic lupus erythematosus is important in clinical practice.

Hashimoto thyroiditis is associated with new-onset systemic lupus erythematosus (SLE) risk, according to the results of a study published in Arthritis Research & Therapy.

Compared with the general population, patients with SLE are associated with a higher risk of developing thyroid diseases.

To evaluate the association between SLE and Hashimoto thyroiditis, researchers conducted a retrospective cohort study, using data from the National Health Insurance Research Database (NHIRD), which includes health data from 95% of Taiwan’s residents since 1995.

Participants who had 3 outpatient visits or 1 hospitalization for autoimmune thyroiditis between 2003 and 2012 were evaluated for new-onset SLE risk through 2013. Control participants with no evidence of thyroid-associated disorders were also included in the study as a comparator cohort. To balance for cohort differences, a 1:20 age-matching approach and a 1:2 propensity-score matching approach were used.

The primary study outcome was SLE occurrence.

A total of 15,512 patients (mean age, 43.4±16.0 years; 86.2% women) with Hashimoto thyroiditis and 31,024 control participants (mean age, 43.4±16.0 years; 86.2% women) were included in the study. Overall, 38.4% and 99.8% of the patient and control group, respectively, did not have hyperthyroidism or hypothyroidism (P <.001). Overall, the patient group had more comorbidities than the control group (P <.001), except for chronic kidney disease, inflammatory bowel disease, and HIV. Among patients with Hashimoto thyroiditis, 54.4% received antithyroid medications and 19.4% received hydroxychloroquine or corticosteroids.

It could provide hints for further research to clarify the pathogenesis between HT, hypothyroidism, hyperthyroidism, and SLE.

In the fully matched groups, Hashimoto thyroiditis was associated with higher rates of SLE, without a follow-up restriction (incidence rate ratio [IRR], 3.58; 95% CI, 2.43-5.28; P <.001), at the 3-month follow-up (IRR, 3.45; 95% CI, 2.31-5.15; P <.001), and at the 6-month follow-up (IRR, 3.57; 95% CI, 2.35-5.40; P <.001).

In the Cox proportional hazard regression analyses, risk for SLE was associated with Hashimoto thyroiditis (hazard ratio [HR], 3.54; 95% CI, 2.40-5.22) and among the subset of individuals with Hashimoto thyroiditis without hyperthyroidism or hypothyroidism (HR, 3.47; 95% CI, 2.12-5.69), Hashimoto thyroiditis with hypothyroidism (HR, 4.27; 95% CI, 2.67-6.83), and Hashimoto thyroiditis with both hyperthyroidism and hypothyroidism (HR, 3.77; 95% CI, 1.76-8.05), but not Hashimoto thyroiditis with hyperthyroidism (HR, 1.72; 95% CI, 0.68-4.35).

The findings of the study may have been biased, as smoking status data, which is a known confounding factor of SLE, were not available.

The study authors concluded, “This population-based study suggested an increased risk of SLE in the [Hashimoto thyroiditis] group after adjustment for baseline characteristics, comorbidities, and medical confounders compared with the reference group. It could provide hints for further research to clarify the pathogenesis between [Hashimoto thyroiditis], hypothyroidism, hyperthyroidism, and SLE.”

References:

Lin H-C, Chang H-M, Hung Y-M, Chang R, Chen H-H, Wei JC-C. Hashimoto’s thyroiditis increases the risk of new‑onset systemic lupus erythematosus: a nationwide population‑based cohort study. Arthritis Res Ther. 2023;25(1):20. doi:10.1186/s13075-023-02999-8