Bacteremia in Systemic Lupus Erythematosus in Patients from a Spanish Registry: Risk Factors, Clinical and Microbiological Characteristics, and Outcomes

Objective. To describe the incidence of bacteremia in a large multicentric cohort of patients with systemic lupus erythematosus (SLE) and their clinical characteristics and to identify risk factors. Methods. All bacteremic episodes from the Spanish RELESSER registry were included. Clinical and laboratory characteristics concerning bacteremia and SLE status, as well as comorbidities at the time of infection, were retrospectively collected. A comparison with sex-and age-matched SLE controls without bacteremia was made. A logistic regression was conducted. Results. The study included 114 episodes of bacteremia in 83 patients. The incidence rate was 2.7/1000 patient-years. At the time of bacteremia, the median age was 40.5 (range: 8-90) years, and 88.6% of patients were female. The Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index was 4 [interquartile range (IQR) 8]; 41% had an SLE flare (66% severe); Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index was 3 (IQR 4). A comorbidity was recorded in 64% of cases. At the time of bacteremia, 88.6% received corticosteroids (68.6% > 10 mg/day) and 57% immunosuppressors. Gram-negative bacilli, most frequently Escherichia coli (29.8%), caused 52.6% of the episodes. The bacteremia-related mortality was 14% and bacteremia was recurrent in 27.2% of cases. A dose-response relationship was found between corticosteroids and bacteremia risk. In the multivariate analysis, these factors were associated with bacteremia: elevated creatinine (OR 1.31, 95% CI 1.01-1.70; p = 0.045), diabetes (OR 6.01, 95% CI 2.26-15.95; p < 0.001), cancer (OR 5.32, 95% CI 2.23-12.70; p < 0.001), immunosuppressors (OR 6.35, 95% CI 3.42-11.77; p < 0.001), and damage (OR 1.65, 95% CI 1.31-2.09; p < 0.001). Conclusion. Bacteremia occurred mostly in patients with active SLE and was frequently associated with severe flares and corticosteroid use. Recurrence and mortality were high. Immunosuppressors, comorbidities, and disease-related damage were associated with bacteremia.