Clinical Features of and Risk Factors for Infection in Patients with Rheumatoid Arthritis

Background: To explore the infection characteristics of patients with rheumatoid arthritis(RA) and related risk factors for infection. Methods This was a retrospective analysis of the clinical data of 648 hospitalized patients with RA, related risk factors for infection and infection sites, pathogens, and drug resistance patterns. The chi-square test 、Mann-Whitney U test and binary logistic-regression analysis were used to identify risk factors. Results A total of 648 patients with RA had 182 cases of infection, and the infection rate was 28.09%. Common infections were pneumonia(19.60%), urinary tract infections(5.25%), and upper respiratory tract infections(5.09%). Gram-negative bacteria ranked first in terms of pathogen composition (67.57%), and the main pathogenic bacteria were Pseudomonas aeruginosa and Escherichia coli ; Staphylococcus aureus was the main pathogenic bacteria species among the gram-positive bacteria. The proportion of resistant isolates was relatively high, and the gram-negative bacteria had a relatively high sensitivity to penicillins/cephalosporins + β-lactamase inhibitors, aminoglycosides, and carbapenems. The risk factors included older age (P = 0.020), a long disease duration (P = 0.004), smoking (P = 0.016), hypoproteinaemia (P = 0.010),and the use of corticosteroids (P < 0.01).The use of nonbiologic disease-modifying antirheumaic drugs(DMARDs) was negatively associated with infection(P = 0.006). Conclusions Our results indicate that the most common infection sites in patients with RA were the respiratory and urinary tracts. Gram-negative bacteria were the common pathogens. RA patients with older age, a long disease duration, smoking, hypoproteinaemia, and long-term use of corticosteroids were prone to infection. Nonbiologic DMARDs use was significantly associated with a decreased risk for infection. The proportion of drug-resistant infections in patients with RA was relatively high.