The impact of multimorbidity on Quality of Life in inflammatory myopathies: A cluster analysis from the COVAD dataset

OBJECTIVE: The presence of comorbidities can substantially affect patients' quality of life, but data regarding their impact on idiopathic inflammatory myopathies (IIMs) are limited. METHODS: We examined the prevalence of comorbidities in IIM patients, other autoimmune rheumatic diseases (oAIRDs) and healthy controls (HCs), using data from the self-reported COVAD-2 survey. We defined basic multimorbidity (BM) as the presence of ≥2 non-rheumatic chronic conditions and complex multimorbidity (CM) as the presence of ≥3 non-rheumatic chronic conditions affecting ≥3 organ systems. Hierarchical clustering on principal components was performed for grouping. RESULTS: Among the COVAD respondents, 1558 IIMs, 4591 oAIRDs and 3652 HCs were analysed. IIMs exhibited a high burden of comorbidities (odds ratio [OR]: 1.62 vs oAIRDs and 2.95 vs HCs, P…