Exposure to antibiotics increases the risk of developing rheumatoid arthritis, say researchers writing in the journal Rheumatology this month.
More than 20 years ago, it was speculated that rheumatoid arthritis might have a bacterial cause. Subsequent studies have suggested that any bacterial involvement in rheumatoid arthritis may be a product of changes in the patient’s microbiota, and next-generation gene sequencing techniques have enabled differences in the gut microbiota between patients with and without rheumatoid arthritis to be identified. Antibiotic therapy has been suggested as one therapeutic approach for rheumatoid arthritis, and restoration of the microbiota using probiotics or fecal transplantation have shown promising results. A prior case control study indicated a relationship between prior antibiotic prescription and the onset of juvenile idiopathic arthritis, but whether this relationship holds for adult rheumatoid arthritis is unknown.
This 15-year case-control study compared 8,482 patients with newly diagnosed rheumatoid arthritis between 2006 and 2018 and 22,661 controls to test the hypothesis that prior antibiotic use influences the risk of developing rheumatoid arthritis.
A higher likelihood of a rheumatoid arthritis diagnosis was evident after antibiotic prescriptions within one year, five years and ever with a strong dose-response. Patients receiving more than 10 antibiotics in a five-year period were more than twice as likely to receive a rheumatoid arthritis diagnosis as controls [adjusted odds ratio 2.65 (CI 2.40, 2.93)]. Antibiotics prescribed more than a decade earlier had the strongest association with a later rheumatoid arthritis diagnosis.
“There seemed a dose response relationship with higher numbers of prescriptions, indicating a greater risk of RA,” wrote the authors, led by David Armstrong, C.B.E., of King's College London in the U.K.
“The results also seem in agreement with a damaged microbiome hypothesis, in that prescription density over time was the best predictor. In other words, the potentially damaging effects of antibiotic prescription several years prior to the diagnosis of RA showed an accumulating pattern,” the authors wrote.
The findings showed some similarities to those linking antibiotic exposure to juvenile idiopathic arthritis, suggesting there may be a common bacterial or microbiome etiology in the two conditions, but this was difficult to determine as the two antibiotic groups examined in this latest study are classed as broad spectrum. However, small differences in the risk associations of penicillins and quinolones might support the role of specific bacteria that show differential susceptibilities to these two antibiotics classes.
As an alternative explanation to the findings linking antibiotics to rheumatoid arthritis, the authors wrote, “Patients with pre-symptomatic or early undiagnosed RA may have been more likely to present to their general practitioner with infections due to an unrecognized effect of RA.”
David Armstrong, Alex Dregan, Mark Ashworth, et al. “Influence of prior antibiotic use on risk of rheumatoid arthritis: case control study in general practice.” Rheumatology (Oxford). October 3, 2019. doi:10.1093/rheumatology/kez452