medwireNews: Results of a real-world study suggest that recurrent infections occur frequently among treated patients with rheumatoid arthritis (RA), and that the type of the initial infection is associated with subsequent infection risk.
James Galloway (King’s College London, UK) and colleagues used the British Society for Rheumatology Biologics Register - Rheumatoid Arthritis registry to analyze data from 5289 patients who experienced at least one serious infection over 19,431 patient–years of follow-up. Over half of the patients were treated with a tumor necrosis factor inhibitor, while approximately a third were treated with conventional DMARDs only, 10% were receiving rituximab, and the remainder were given tocilizumab.
The annual incidence of serious infection was 4.6% per year at baseline, and this rose to 14.2% following an index infection. Patients were at highest risk for recurrent infection within the first 3 months of having an index infection, and the most common type of infection was respiratory, accounting for 44.0% of all events.
These findings suggest that “[r]ecurrent infections in RA are common,” report the researchers in Rheumatology.
“When choosing a biologic for a patient without prior history of infection, small differences in relative risk may have little clinical significance when absolute rates of infection are considered,” but for those who have already had an infection, “even small differences in relative infection risk may become significant,” they explain.
The team also found that the type of incident infection had “a large impact” on the likelihood of recurrent infection.
Indeed, patients who experienced sepsis had the highest annual risk for any recurrent infection, at 19.7%, followed by those with respiratory and genitourinary infections, at 15.0% and 14.5%, respectively.
In a multivariable analysis, patients who experienced sepsis as an index infection had a significant 1.32-fold higher risk for recurrent infection than those with a respiratory tract infection after adjustment for factors including age, sex, disease activity, and smoking.
Furthermore, increasing age and polypharmacy – a surrogate measure of comorbidity – were associated with a significantly elevated risk for recurrent infection in the multivariable model.
Although this was the first study to quantify the burden of recurrent serious infection “in a contemporary, real world representative RA cohort,” Galloway and co-authors caution that the cohort “was highly skewed towards patients with severe disease requiring biologic therapy,” meaning that the findings may not be generalizable to all patients with RA. They also note that the impact of individual drugs on infection risk was not assessed.
And the team concludes that further studies should be carried out “to understand the patterns of recurrent infection and to appreciate the nuances in differential infection profiles of immunosuppressive drugs.”
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