A case-control study on autoimmune polyendocrine syndromes in patients with systemic lupus erythematosus

Objectives This study aimed to investigate the prevalence of autoimmune polyendocrine syndromes in patients with SLE and to assess whether autoimmune polyendocrine syndromes predict higher disease activity or worse outcomes. Methods The clinical charts of 417 SLE patients (meeting SLICC 2012 and/or EULAR/ACR 2019 criteria) (referred to our centre between 2021 and 2023 were analysed. Autoimmune polyendocrine syndrome cases were identified using ORPHA definitions; 185 autoimmune polyendocrine syndrome-free SLE patients, randomly enrolled, served as controls. Demographic, clinical and serological data were collected. Results Forty-seven of 417 (11%) SLE patients had another autoimmune disease affecting the glands that allowed the diagnosis of autoimmune polyendocrine syndrome: 39 were diagnosed with Hashimoto thyroiditis, 6 with Graves' disease, and 3 with type 1 diabetes mellitus. Forty-five were affected by autoimmune polyendocrine syndrome type 3, and 2 by autoimmune polyendocrine syndrome type 4; no patients were diagnosed with autoimmune polyendocrine syndrome types 1 or 2. A comparison between the autoimmune polyendocrine syndrome-positive and -negative patients revealed no significant differences in clinical or serological features. At the last evaluation, ∼80% of both groups of patients were in clinical remission, and approximately half of the patients remained on steroid therapy. Autoimmune polyendocrine syndrome-positive patients had a slightly higher median SLICC Damage Index (SDI), although this was not associated with increased disease activity. Conclusion The prevalence of autoimmune polyendocrine syndrome among SLE patients is significantly higher than in the general population (11% vs 0.005%), confirming the association between autoimmune thyroiditis and SLE. However, autoimmune polyendocrine syndrome-positive patients do not appear to have a more aggressive disease or develop more complications.