Abstract
Objective We estimated the incidence of various comorbidities and mortality in a large national cohort of patients with newly diagnosed systemic lupus erythematosus (SLE) compared with matched population comparators.
Methods All patients aged ≥ 18 years with a first-time diagnosis of SLE in the Danish National Patient Register from 1996 to 2018 were included (n = 3178). For each patient with SLE, 19 age- and sex-matched population comparators were identified (n = 60,090). Comorbidity diagnoses and mortality data were retrieved from national Danish registries. For comorbidities and mortality, incidence rates per 1000 person- years and age- and sex-adjusted incidence rate ratios (IRRs) were estimated during the following time intervals following SLE diagnosis: year 1, year 2, years 3-5, and years 6-10.
Results A total of 84.3% of patients with SLE and general population comparators were female, and the mean age at baseline was 47.4 years. Patients with SLE had a significantly increased risk of developing comorbidities during follow-up. The following highest first-year IRRs were seen for typical features of SLE: coagulopathy, renal disease, and pulmonary embolism. Renal disease, coagulopathy, and osteoporosis had the highest IRRs during the 5-10 years of follow-up. Patients with SLE had 4.1-times increased mortality risk during the first year of follow-up compared with matched population controls, and 1.6- to 2.1-times increased mortality risk during subsequent follow-up periods.
Conclusion The study provides a comprehensive overview of risk estimates and the timing of comorbidities and mortality in a nationwide cohort of adult patients with SLE. These data may be a valuable reference for upcoming works on evaluating comorbidity in SLE.
