Recent infections may curb risk of rheumatism

Published 2015-02-05 10:39. Updated 2015-02-10 18:34

Recent gut and urinary tract infections may curb the risk of developing rheumatoid arthritis, suggests a new study from Karolinska Institutet published online in the journal Annals of the Rheumatic Diseases. According to the researchers, one possible explanation could lie in the way in which these infections alter the types of bacteria resident in the gut (microbiome).

The research team set out to look at the impact of different types of infection on the risk of developing rheumatoid arthritis in almost 6500 people living in south and central Sweden. Of the entire sample, 2831 had been newly diagnosed with rheumatoid arthritis between 1996 and 2009. The remaining 3570, who were randomly selected from the population, were healthy, but matched for age, sex, and area of residence with the patients. The average age of all participants at study entry was 52, and 7 out of 10 of them were women.

All participants were asked whether they had had any gut, urinary tract, or genital infections in the preceding two years. They were also asked if they had had prostatitis (inflamed prostate), or antibiotic treatment for sinusitis, tonsillitis/other throat infection, or pneumonia during this time.

Significantly lowered risk 

Gut, urinary tract, and genital infections within the preceding two years were each associated with a significantly lowered risk of developing rheumatoid arthritis: 29 percent, 22 percent, and 20 percent, respectively. Further, having all three types of infection in the preceding two years was linked to a 50 percent lower risk, after taking account of influential factors. 

By contrast, no such associations were found for recent respiratory infections and pneumonia. Factoring in smoking and socioeconomic background made no difference to the overall findings. However, since this is an observational study researchers point out that no definitive conclusions can be drawn about cause and effect.

Lead author of the current study is Maria Sandberg, PhD, at Karolinska Institutet’s Institute of Environmental Medicine . The work was financially supported by grants from the Swedish Medical Research Council, the Swedish Research Council for Health, Working Life and Welfare, the AFA foundation, Vinnova, King Gustaf V’s 80-year foundation, the Swedish Rheumatic Foundation, and the Swedish Foundation for Strategic Research.  This news article is an adapted version of a press release from BMJ Journals.


Recent infections are associated with decreased risk of rheumatoid arthritis –a population-based case-control study
Maria EC Sandberg, Camilla Bengtsson, Lars Klareskog, Lars Alfredsson, Saedis Saevarsdottir
Annals of the Rheumatic Diseases, online first 5 February 2015,  doi 10.1136/annrheumdis-2014-206493

Infectious Disease MedicineRheumatology