Introduction: Celiac disease (CD) is a chronic systemic immune-mediated disorder that occurs in genetically predisposed people upon ingestion of gluten. The complications and associations of CD are wide-ranging, with notable associations with other autoimmune diseases. Few studies have described the association of CD with inflammatory myopathies, such as polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM). However, there have been no studies interrogating the association in large cohorts. We investigated these relationships using a large nation-wide patient dataset.
Methods: Utilizing IBM Explorys® (Cleveland, OH), a database encompassing over 80 million patients in the United States and spanning the last two decades, we defined groups of patients identified with three idiopathic inflammatory myopathies using SNOMED Clinical Terms®. We collected age, gender, and race-based demographics, in addition to comorbidities including hypothyroidism, alcohol use disorder, tobacco use, and CD, and subsequently performed binary logistic regression using IBM SPSS Statistics® v26 (Chicago, IL) to determine significant associations.
Results: In the database, which contained 80,920,060 patients at the time of querying, there were 143,330 CD patients (0.18%). 18,270 (0.02%) of the total patients met the definition of dermatomyositis, with 160 (0.88%) of these carrying the diagnosis of CD, while there were 8,970 (0.01%) polymyositis patients (of which there were 70 / 0.78% with CD) and 1,520 (0.002%) IBM patients (30 / 2% with CD). Following logistic regression that incorporated demographics and several comorbidities, CD was significantly associated with all inflammatory myopathies: the OR for CD in dermatomyositis was 3.55 (95%CI 3.11 — 4.04, p< 0.001), 3.23 in polymyositis (95%CI 2.89 — 3.60, p< 0.001) and 11.60 in IBM (95%CI 9.02 — 14.92, p< 0.001).
Discussion: In this very large aggregate of patients across the United States, CD was significantly associated with the idiopathic inflammatory myopathies of polymyositis, dermatomyositis, and IBM after accounting for a number of possible confounders. Clinicians should be aware of this relationship when assessing myalgia in celiac disease patients.
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