Gut and Urinary Infections May Prevent Rheumatoid Arthritis

Recent stomach and urinary tract infections may be linked to a reduced risk of rheumatoid arthritis (RA), according to findings published in The Annals of Rheumatic Diseases.

Researchers from the Karolinska Institutet in Sweden conducted a study of 2,831 people with incident RA and 3,570 healthy controls who were matched for sex, age, calendar period, and area of residents in order to determine if recent infections affect the risk of RA. The patients’ average age was 52 years, and about 70 percent of the participants were female. The patients had at least 1 of the following diseases during the 2 years prior to the time they were included in the study: gastroenteritis, urinary tract infection, genital infection, prostatitis, sinusitis, tonsillitis, and pneumonia. The patients’ smoking and socioeconomic status were also considered.

The researchers found those participants with a recent gastrointestinal and urogenital tract infections — such as gastroenteritis, urinary tract infections, and genital infections – before clinical onset were associated with a lowered risk of RA. Specifically, RA risk was reduced by 29, 22, and 20 percent for patients with gut infections, urinary tract infections, and genital infections, respectively. Those patients with all 3 infections within 2 years prior to the study were 50 percent less likely to develop RA.

The less common prostatitis had a non-significant association with RA, the researchers noted. There was no associated noted by the researchers for a link between sinusitis, tonsillitis, or pneumonia.

An explanation the researchers offered for this effect is that certain infections may alter the types of digestive system bacteria. The researchers also noted the antibiotics used to treat gut, urinary, and genital infections are effective in treating RA.

However, the researchers commented that their data depended heavily on self reports, which may sometimes be unreliable. No causal connection between infection and rheumatoid arthritis was found, the researchers stressed.

“We hope it inspires further research that may give rise to new treatments in the future,” lead author Maria E. C. Sandberg, postdoctoral researcher at the Karolinska Institutet told The New York Times.