Thyroid disorders assessment: an unmet need in patients with idiopathic inflammatory myopathies?

BackgroundThyroid diseases (TD) might compromise health status of patients, in particular owing to their possible impact on cardiovascular risk, bone mineral density (BMD) and muscle function. The prevalences of Hashimoto thyroiditis (HT), multinodular goiter (MNG) and Graves’ disease (GD) in general population correspond respectively to about 12%, 10% and 1.3%; it is well known HT represents a risk factor for the development of thyroid papillary cancer (TPC). Idiopathic inflammatory myopathies (IIMs) are rare systemic autoimmune disorders, with a pleiotropic clinical picture. TD are a known comorbidity of patients with connective tissue diseases; in particular, they might increase the risk of osteoporosis (OP) and fragility fractures (FF) in patients with SLE1. A recent study described the association between IIMs and both hyper- and hypo-thyroidism2.ObjectivesTo evaluate the prevalence of TD in a monocentric cohort of patients with IIMs, exploring possible correlations with serology, organ involvement and comorbidities.MethodsWe retrospectively analyzed medical records of consecutive patients diagnosed with IIM according the EULAR/ACR 2017 criteria and regularly followed at our specialistic outpatient Myositis Clinic from January 2018 to December 2021. We collected data about demography, subset and duration of disease, organ involvement, serology, thyroid dysfunction and other comorbidities. As TD, we took into account the occurrence of HT, MNG and GD. Intergroups comparisons were assessed by using Chi-square, t-test and ANOVA. P values <0.05 were considered significant.ResultsThe clinical charts of 151 patients were examined: 101 (66,9%) were female, the mean age was 65,1±14,0 years and the mean disease duration was 8,5±6,5 years. Clinical diagnosis were the following: 69 (45.7%) polymyositis, 59 (39.1%) dermatomyositis, 11 (7.3%) clinically amyopathic dermatomyositis, 10 (6.6%) inclusion body myositis, 2 (1.3%) juvenile dermatomyositis. Seventy-five patients (49.7%) had a TD; in particular, 39/151 (25.8%) had MNG, 34/151 (22.6%) had HT and 2/151 (1.3%) GD. The presence of a TD was significantly related with esophagus’ involvement (p=0.037), Raynaud’s phenomenon (RP) (p=0.045), sicca syndrome (SiS) (p<0,001), OP (p<0,001) and cataract (p=0,017). In particular, HT and MNG occurrence was respectively associated with a higher risk of OP (p<0,001) and of sicca syndrome (p<0,001). Interestingly, TD were significantly less frequent in patients with anti-Mi2beta autoantibodies (p=0,003) and anti-Jo1 autoantibodies (p=0,026). No further significant correlations emerged.ConclusionOur study showed nearly half of our IIMs patients had a TD, with a prevalence of both MNG and HT significantly higher than in general population; besides, owing to the retrospective nature of our study, these data could be underestimated. In addition to correlating with RP and SiS, TD showed a significant association with esophagus involvement; this result should be confirmed and clarified with future analyses. Moreover, in our cohort, TD were confirmed as a risk factor for a compromised BMD; in particular, HT was significantly associated with the occurrence of OP. Further studies are needed to corroborated our data in other cohorts of IIM patients and to explore if TD represent a risk factor for FF also in IIM; finally, since HT is a risk factor for TPC, an evaluation of its occurrence in our cohort should be designed. However, our data seem sufficient to underline the need to regularly screen IIM patients for thyroid function, aiming at optimizing their quality of care, both for activity and damage domains of their autoimmune disease.References[1]Carli L, et al. Risk factors for osteoporosis and fragility fractures in patients with systemic lupus erythematosus. Lupus Sci Med. 2016 Jan 19;3(1):e000098.[2]Watad A, et al. Dysthyroidism in dermato/polymyositis patients: A case-control study. Eur J Clin Invest. 2021;51:e13460.Disclosure of InterestsNone declared