Association between Graves' disease and risk of incident systemic lupus erythematosus: A nationwide population-based cohort study

OBJECTIVE

Previous case reports have linked Graves' disease to incident systemic lupus erythematosus (SLE). It has also been reported that antithyroid drugs used to treat Graves' disease can induce SLE development. The purpose of this study was to investigate the risk of SLE in patients with Graves' disease.

METHODS

A total of 8779 patients with Graves' disease and 8779 controls (without Graves' disease) matched by age, gender, index year, and Charlson Comorbidity Index (CCI) score were enrolled between 2000-2012. Patients were then followed until the end of 2013 using Taiwan's National Health Insurance Research Database, at which time participants who developed SLE were identified. Cox regression analysis was used to calculate the hazard ratio (HR) with a 95% confidence interval (CI) of SLE incidence rate between patients with Graves' disease and unaffected controls.

RESULTS

Patients with Graves' disease had a significantly increased risk of SLE than unaffected controls (8.81 vs 2.83 per 10 000 person-years, HR: 5.45, 95% CI: 1.74-17.0) after adjusting for antithyroid therapies (antithyroid drugs, radioactive iodine ablation, and surgery). Diagnostic bias may be present as patients with Graves' disease may seek more help from healthcare providers. After excluding the first 0.5 and 1 year of observation period, similar results were obtained (excluding 0.5 year - HR: 4.30, 95% CI: 2.78-8.57; excluding 1 year - HR: 4.63, 95% CI: 2.33-7.79).

CONCLUSION

This study shows that Graves' disease is associated with an increased risk of incident SLE. Further studies on the underlying pathogenesis linking Graves' disease and SLE are warranted.

Association between systemic lupus erythematosus and thyroid dysfunction: a meta-analysis

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease, the pathogenesis of which remains elusive. The deficiency or excess of thyroid hormone is defined as thyroid dysfunction, including (subclinical) hypothyroidism and (subclinical) hyperthyroidism. Autoimmune factors are likely to be relevant to the development of SLE and thyroid dysfunction. Recently, many studies have indicated that the prevalence of thyroid dysfunction is higher in SLE patients than in the general population. The objective of our study was to perform a systematic review and meta-analysis to find out the relationship between SLE and thyroid dysfunction.

METHODS

Literature databases were searched, including PubMed, Embase, Web of science, Cochrane, CNKI, CHINESE WANFANG, China Science and Technology Database (VIP). Studies comparing presence of thyroid dysfunction in SLE patients to healthy controls were extracted. All the statistical analyses were performed with STATA 12.0 software.

RESULTS

Ten studies with 10,500 SLE patients and 44,170 healthy controls were included in this study. The meta-analysis results showed that the prevalence of (subclinical) hypothyroidism in SLE patients was higher than in the healthy controls (hypothyroidism: OR = 2.93, 95% CI = 1.81-4.75; subclinical hypothyroidism: OR = 5.67, 95% CI = 3.50-9.18). No statistical difference of (subclinical) hyperthyroidism was found between SLE patients and controls.

CONCLUSION

Our meta-analysis suggests that SLE is significantly associated with increased risk of (subclinical) hypothyroidism, but it has little influence on (subclinical) hyperthyroidism.