Could antibiotics increase the risk of RA?

A history of taking antibiotics is associated with a higher risk of developing rheumatoid arthritis, a large case-control study suggests

---

A history of taking antibiotics is associated with a higher risk of developing rheumatoid arthritis, a large case-control study suggests.

According to the UK study, recently published in BioMed Central, the odds of developing rheumatoid arthritis were 60% higher among individuals exposed to one or more courses of antibiotics in the previous 10 years prior to diagnosis than in their matched unexposed counterparts.

And the risk increased with the more courses of antibiotics the individual received. More recent exposure of antibiotics was also found to increase the odds of developing rheumatoid arthritis.

To conduct the study, researchers used primary care data to identify more than 22,000 patients with rheumatoid arthritis and compare their history of infection and antibiotic prescription with more than 90,000 controls matched by gender, age and location.

Along with frequency of antibiotics, the risk of developing rheumatoid arthritis also seemed to vary according to the class and mode of action of the antibiotic.

Bactericidal antibiotics carried a higher risk than bacteriostatic antibiotics (45% vs 31%).

And the type of infection being treated appeared important, with respiratory tract infections showing the strongest association. But while previous research had suggested the bacteria commonly associated with these infections may be responsible for the increase in autoantibodies associated with rheumatoid arthritis, this study suggests it is the antibiotics.

“Our analysis indicates the strongest association is only present in antibiotic-treated cases of [upper respiratory tract infections] ….not untreated [infections], suggesting that associated antibiotic usage is likely to be the main associative factor for increased incidence of rheumatoid arthritis in this cohort.”

The researchers suggest that gut microbiota disturbances might account for the link between antibiotics and the development of rheumatoid arthritis. They point to existing strong evidence linking antibiotic-induced microbiota disturbances to numerous conditions, such as inflammatory bowel disease.

“…Even short-term changes [in gut microbiota from antibiotics] may interrupt the key immune pathways, which may manifest as symptoms in later-life conditions,” the study authors said.

Professor Michelle Leech at the Centre for Inflammatory Disease at Monash University, commenting on the study, said the research didn’t examine how genetic factors and a patient’s predisposition to developing rheumatoid arthritis might affect their health prior to diagnosis.

“My question is; to what extent are patients with rheumatoid arthritis who received antibiotics actually having more infections and illnesses, compared to other people?

“Antibiotics affect the gut microbiota and the gut itself seems important in regulating the intensity of the immune system, but we can’t be sure about a causal link yet to rheumatoid arthritis.”

BMC Medicine, 7 August