Hashimoto’s thyroiditis increases the risk of new-onset systemic lupus erythematosus: a nationwide population-based cohort study

<jats:title>Abstract</jats:title><jats:sec>
<jats:title>Background</jats:title>
<jats:p>Previous studies have shown systemic lupus erythematosus (SLE) patients had a significantly higher prevalence of thyroid diseases and hypothyroidism than matched controls, and some case reports showed SLE may occur after Hashimoto’s thyroiditis (HT).</jats:p>
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<jats:title>Objective</jats:title>
<jats:p>This study aimed to investigate the subsequent risk of SLE in patients with HT.</jats:p>
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<jats:title>Methods</jats:title>
<jats:p>In this retrospective cohort study done by the Taiwan National Health Insurance Research Database, the HT group (exposure group) and the non-HT group (comparator group) were propensity score matched at a ratio of 1:2 by demographic data, comorbidities, medications, and the index date. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Several sensitivity analyses were done for cross-validation of our findings.</jats:p>
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<jats:title>Results</jats:title>
<jats:p>We identified 15,512 HT patients and matched 31,024 individuals. The incidence rate ratio of SLE was 3.58 (95% CI, 2.43–5.28; <jats:italic>p</jats:italic> < 0.01). Several sensitivity analyses show adjusted hazard ratio (aHR) (CIs) of 4.35 (3.28–5.76), 4.39 (3.31–5.82), 5.11 (3.75–6.98), and 4.70 (3.46–6.38), consistent with the results of the main model.</jats:p>
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<jats:title>Conclusion</jats:title>
<jats:p>Our study showed an increased risk of SLE in the HT group after adjustment for baseline characteristics, comorbidities, and medical confounders compared with the reference group.</jats:p>
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