Certain Common Infections Might Transiently Lower Risk for RA

For decades, clinicians have speculated that common infections might serve as triggers for onset of rheumatoid arthritis (RA). Yet, we have little epidemiologic evidence for this phenomenon.

In a population-based, case-control study in Sweden, researchers identified 2831 incident cases of RA and selected age-, sex- and community-matched controls without RA. All participants were surveyed about common infectious syndromes they had experienced during the 2 years before onset of RA in the index cases. Occurrence of gastroenteritis, urinary tract infections, and genital infections seemed to protect against developing RA (odds ratios, 0.71–0.80), whereas respiratory infections (tonsillitis, sinusitis, and pneumonia) did not affect risk for develo…