Background Infection occurs frequently in patients with systemic lupus erythematosus (SLE) and has been a major cause of morbidity and mortality. However, no large-scale comprehensive studies have estimated the effect of clinical characteristics on serious infections in actual clinical practice yet. We investigated the influence of clinical characteristics on serious infections using electronic medical record data.

Methods We conducted a nested case-control study. Patients with SLE who developed serious infections needing hospitalization or intravenous antibiotic administration were matched to controls who did not. Odds ratios (ORs) and 95% confidence intervals (CIs) for infection associated with the clinical characteristics were obtained using logistic regression analyses.

Results Among the total of 120 cases with infection, 93 (77.5%) were bacterial infections with 40 (25%) upper respiratory tract infections, 26 (21.7%) pneumonia, 24 (20%) sepsis, and 22 (18.3%) urinary tract infections. The patients with serious infections had lower hemoglobin and C3 levels and less frequent hydroxychloroquine administration. In addition, they had more frequent nephritis, serositis, and hematologic involvement and took higher than the low dose of glucocorticoids (GCs;>7.5 mg/d prednisolone-equivalent). The conditional logistic regression analysis with adjustment showed that serositis (OR, 2.76; 95% CI, 1.33–5.74), hematologic involvement (OR, 2.53; 95% CI, 1.32–4.87), and use of higher than the low dose of GCs (OR, 2.65; 95% CI, 1.31–5.34) were related to serious infections in SLE

Conclusions Serositis, hematologic involvement, and use of higher than the low dose of GCs are risk factors for serious infections in patients with SLE.

Funding Source(s): This research was supported by a grant from the Korea Health Technology R and D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea (grant number: HI16C0992).