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

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.

We conducted a total population-based case-control study to explore the prior comorbidities associated with SLE.

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.

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 < 0.001) in the 5 years before the index date. Negatively associated comorbidities could be attributed to diabetes mellitus and pregnancy related symptoms.

Our results supported that increased awareness of SLE may be warranted for patients with autoimmune-related comorbidities of multiple organs. However, diabetes mellitus and pregnancy related symptoms were negatively associated with SLE incidence in this study. Further studies are warranted to elucidate the possible underlying mechanism and for better understanding the pathogenesis of SLE.