Factors associated with disease flare following SARS-CoV-2 vaccination in people with inflammatory rheumatic and musculoskeletal diseases

Objectives: To investigate the frequency and factors associated with disease flare following vaccination against SARS-CoV-2 in people with inflammatory/autoimmune rheumatic and musculoskeletal diseases (I-RMDs). Methods: Data from the European Alliance of Associations for Rheumatology Coronavirus Vaccine physician-reported registry were used. Factors associated with flare in patients with I-RMDs were investigated using multivariable logistic regression adjusted for demographic and clinical factors. Results: The study included 7336 patients with I-RMD, with 272 of 7336 (3.7%) experiencing flares and 121 of 7336 (1.6%) experiencing flares requiring starting a new medication or increasing the dosage of an existing medication. Factors independently associated with increased odds of flare were: female sex (OR=1.40, 95% CI=1.05 to 1.87), active disease at the time of vaccination (low disease activity (LDA), OR=1.45, 95% CI=1.08 to 1.94