[Clinical characteristics and risk factors of patients with rheumatoid arthritis complicated with urinary tract infection].

OBJECTIVE: To explore the clinical characteristics of urinary tract infection (UTI) in patients with rheumatoid arthritis (RA), to evaluate the effects of different treatment regimens on the risk of UTI, and to identify independent risk factors for UTI complicated with RA.

METHODS: A retrospective cohort study was conducted. RA patients hospitalized in the Department of Rheumatology and Immunology, The First Affiliated Hospital of Baotou Medical College from September 2020 to September 2023 were enrolled. General clinical data, laboratory indicators and medication information of the patients were collected. Patients were divided into two groups according to the presence or absence of UTI for comparative analysis. Patients were grouped based on different treatment regimens received, and the proportions of UTI occurrence were compared among each group. The results of urine culture and drug susceptibility test in the RA patients with UTI were analyzed. Univariate and multivariate Logistic regression analyses were further performed to screen relevant factors for UTI in the RA patients, and the diagnostic value of combined indicators was assessed using receiver operating characteristic (ROC) curve.

RESULTS: A total of 196 RA patients were included, among whom 99 cases were complicated with UTI and 97 cases without UTI. Compared with the non-UTI group, the UTI group had higher proportions of female patients, patients aged ≥65 years, patients with RA disease duration ≥10 years, patients hospitalized for infection within the past two years, and patients with comorbidities (diabetes mellitus, hypertension, etc.). Peripheral blood leukocyte count, percentage of neutrophils, serum procalcitonin, erythrocyte sedimentation rate (ESR) and C-reactive protein level were elevated (P < 0.05), while hemoglobin, percentage of lymphocytes and plasma albumin level were decreased (P < 0.05). The RA patients were divided into four groups according to different treatment regimens: ①glucocorticoids (GCs) monotherapy group; ②conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) monotherapy group; ③csDMARDs combined with GCs group; ④ csDMARDs combined with biological DMARDs (bDMARDs)/ targeted synthetic DMARDs (tsDMARDs) group. The overall difference in UTI proportion among the four groups was statistically significant (P < 0.001). After Bonferroni correction, the UTI proportion in group ① and group ③ was higher than that in group ② and group ④ (adjusted P < 0.05). GSs use was associated with increased UTI risk, and the risk of UTI showed an upward trend with the increase of daily dose. Multivariate Logistic regression analysis demonstrated that RA disease duration ≥10 years, previous hospitalization due to infection within the past two years, comorbid diabetes mellitus, and elevated disease activity score in 28 joints based on ESR (DAS28-ESR) were independent risk factors for UTI in the RA patients. The area under the ROC curve of the diagnostic model constructed with the above combined predictors was 0.82 (95%CI: 0.76-0.88), with a sensitivity of 0.67 and a specificity of 0.94. Gram-negative bacteria were the predominant pathogens in urine culture of the RA patients with UTI, among which Escherichia coli accounted for 67.71%. Among evaluable single-isolate bacterial strains with available drug-susceptibility results, the resistance rates to levofloxacin and trimethoprim-sulfamethoxazole were 65.4% and 52.8%, respectively.

CONCLUSION: Clinical infection surveillance should be strengthened in RA patients. GCs should be rationally used on the premise of effective RA disease control, and bDMARDs/tsDMARDs therapy should be initiated timely according to disease status to reduce GCs exposure and minimize the risk of UTI. Meanwhile, antimicrobial agents should be selected in a standardized manner based on urine culture and drug susceptibility test results.