Swedish researchers report in the Annals of the Rheumatic Diseases that there is an increase in the risk of developing arthritis in early adulthood if a child has a serious infection during the first year of his or her life.

Cecilia Carlens (Rheumatology Unit, Department of Medicine, Karolinska University Hospital and Institute, Stockholm, Sweden) and colleagues studied data from national registers on over 3,500 people born between 1973 and 2002. The researchers had access to data on hospital treatments and episodes of arthritic disease as well as information on mother’s health, details of pregnancy and birth, and details of any infections during the first 12 months of the participants’ lives.

The results of the analysis demonstrated that being born early, small, or underweight was associated with a lower likelihood of developing rheumatoid arthritis as a young adult. Having more than three siblings and being large for gestational age were traits linked to a higher probability of rheumatoid arthritis, but these relationships were not statistically significant. In addition, a form of arthritis that affects only young children and teens – juvenile idiopathic arthritis – was found in participants who had a longer-than-average gestational period.

The researchers note, however, that the most significant predictor of arthritis was a hospital stay due to an infection during the first year of life. This characteristic was associated with a doubling of the likelihood of developing rheumatoid arthritis as a young adult, especially of developing a subtype called seronegative rheumatoid arthritis. Carlens and colleagues also found that serious infections almost double the risk of juvenile idiopathic arthritis, with greater risks if the child had respiratory, gut, or skin/soft tissue infections.

An explanation of the association between infections and arthritis begins with the possibility that infections act as acute triggers of arthritis in later life, and the researchers suggest that infections may alter the way in which the immature immune system develops.

Perinatal characteristics, early life infections and later risk of rheumatoid arthritis and juvenile idiopathic arthritis
C Carlens, L Jacobsson, L Brandt, S Cnattingius, O Stephansson, J Askling
Annals of the Rheumatic Diseases (2008).
doi: 10.1136/ard.2008.089342
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Written by: Peter M Crosta