Explore comorbidities associated with systemic lupus erythematosus: a total population-based case–control study

Summary Background Because of the increasing incidence and overall burden of systemic lupus erythematosus (SLE), efforts have been made to identify the factors that contribute to SLE onset and progression. Aim We conducted a total population-based case–control study to explore the prior comorbidities associated with SLE. Design and methods Data were collected from Taiwan’s National Health Insurance Research Database. Newly diagnosed SLE patients from 1 January 2010, to 31 December 2013 (n = 2847), were exactly matched at a 1:4 ratio for gender, age, residence and insurance premium to form a non-SLE group. Multivariate conditional logistic regression with stepwise selection was used to find the prior-associated comorbidities. Results A total of 38 prior comorbidities were associated with SLE incidence (32 positive and 6 negative associations). Positively associated comorbidities could be categorized as autoimmune-related inflammation of multiple organs including skin, blood, liver, tooth, thyroid, musculoskeletal and connective tissue. Among them, diffuse diseases of connective tissue (International Classification of Disease, Ninth Revision, Clinical Modification 710) exhibited the most robust association (OR = 5.68, 95% CI = 4.02–8.03, P