Severe respiratory infections in rheumatoid arthritis patients: an observational study of 528 patients from a single university hospital

Abstract

Patients with rheumatoid arthritis (RA) have an increased risk of infections. This may be linked to disease-related factors, immunosuppressive therapy and the presence of comorbidities. Background/Objectives: In an unselected group of RA patients, our aims were to assess the following: (a) the incidence and (b) features of diseases and (c) the predictive factors of severe respiratory infection (SRI). Methods: An observational and retrospective study of all patients with RA included in the vaccination program of our hospital between October 2011 and October 2018 was conducted. The follow-up continued until December 2020. Patients with SRI, defined as those that required hospitalization or at least one dose of intravenous antibiotic treatment in the emergency room, were (a) compared with those not requiring hospital admission and (b) studied for predictive factors of SRI (multivariate analysis adjusted for age and sex). The vaccination program in our hospital includes vaccination against influenza, S. pneumoniae and H. influenzae. Information on the patients, infections and hospitalizations was retrospectively retrieved from the hospital and general physician records. Results: We studied 528 RA patients (409 women/119 men) with a mean age of 58.9 ± 13.2 years. A total of 55 patients (10.4%) suffered 89 SRIs. The median [IQR] number of hospitalizations per patient was 1.5 [1-2]. Patients with an SRI were older, had had RA for longer and had more comorbidities (hypertension, hypercholesterolemia, diabetes and interstitial lung disease). These patients had more ACPA positivity, more extra-articular manifestations and high disease activity at the time of their vaccination. Treatment with glucocorticoids, methotrexate and leflunomide was seen in a higher number of patients. Predictive factors for SRI were age; time of evolution of RA; associated comorbidities, especially hypertension and diabetes; extra-articular manifestations, especially interstitial lung disease; and treatment with glucocorticoids, methotrexate and leflunomide. Conclusions: Despite being included in a vaccination program, about 10% of our patients required hospitalization due to an SRI. The main predictive factors were certain comorbidities, interstitial lung disease and treatment with glucocorticoids. Predicting SRI in RA patients remains an unmet need.