Staphylococcus aureus sepsis in rheumatoid arthritis.

Patients with rheumatoid arthritis (RA) are at increased risk of infection. In this study, we determined the risk of and risk factors for Staphyococcus aureus (S. aureus) sepsis in RA. We assembled a retrospective nested case-control subset of RA patients with S. aureus sepsis from the Barnes-Jewish Hospital Medical Informatics database, confirmed the diagnoses, and collected data electronically and by chart review. We used multivariate logistic regression to identify independent risk factors for S. aureus sepsis, with risk expressed as odds ratios (ORs). We extracted data on the length of hospitalization and 30-day and 1-year mortality from the Medical Informatics database for all cases and controls. There were 48 confirmed S. aureus sepsis cases and 232 confirmed controls in the RA cohort. In multivariate analysis, indwelling central venous catheter (OR 15.97; 95 % CI 5.09-50.10; p < 0.01) and congestive heart failure (OR 2.89; 95 % CI 1.26-6.63; p = 0.01) were independently associated with risk of S. aureus sepsis, while treatment with disease-modifying anti-rheumatic drugs (DMARDs), both biologic and non-biologic, was not. S. aureus sepsis was associated with increased 30-day and 1-year mortality (OR 7.37; 95 % CI 2.86-19.0; p < 0.01 for 30-day and OR 5.24; 95 % CI 2.51-10.94; p < 0.01 for 1-year mortality) and longer hospitalization (p < 0.01). Treatment with biologic DMARDs was not associated with longer hospitalization (p = 0.89). Indwelling central venous catheters and congestive heart failure increased the risk of S. aureus sepsis in this observational cohort of patients with RA. Treatment with biologic and non-biologic DMARDs did not increase this risk.