Increased risk of severe infections and mortality in patients with newly diagnosed systemic lupus erythematosus: a population-based study

Objective. To evaluate the risk of severe infection and infection-related mortality among patients with newly diagnosed SLE. Methods. We conducted an age- and gender-matched cohort study of all patients with incident SLE between 1 January 1997 and 31 March 2015 using administrative health data from British Columbia, Canada. Primary outcome was the first severe infection after SLE onset necessitating hospitalization or occurring during hospitalization. Secondary outcomes were total number of severe infections and infection-related mortality. Results. We identified 5169 SLE patients and matched them with 25 845 non-SLE individuals from the general population, yielding 955 and 1986 first severe infections during 48 367 and 260 712 person-years follow-up, respectively. The crude incidence rate ratios for first severe infection and infection-related mortality were 2.59 (95% CI: 2.39, 2.80) and 2.20 (95% CI: 1.76, 2.73), respectively. The corresponding adjusted hazard ratios were 1.82 (95% CI: 1.66, 1.99) and 1.61 (95% CI: 1.24, 2.08). SLE patients had an increased risk of a greater total number of severe infections with crude rate ratio of 3.24 (95% CI: 3.06, 3.43) and adjusted rate ratio of 2.07 (95% CI: 1.82, 2.36). Conclusion. SLE is associated with increased risks of first severe infection (1.8-fold), a greater total number of severe infections (2.1-fold) and infection-related mortality (1.6-fold).