To assess the effect of measles, mumps and rubella (MMR) vaccination on disease activity in children with juvenile idiopathic arthritis (JIA).
A retrospective observational multicentre cohort study was performed in 314 patients with JIA, born between 1989 and 1996. Disease activity and medication use were compared during the period of 6 months before vaccination versus 6 months after vaccination. Disease activity was measured by joint counts, the Physician's global assessment scale and erythrocyte sedimentation rate. Next, we compared disease activity in patients vaccinated between 8 and 9 years of age with the activity in patients who had not been vaccinated at this time (who received MMR between the ages of 9 and 10 years).
No increase in disease activity or medication use was seen in the 6 months after MMR vaccination (n = 207), including in patients using methotrexate (n = 49). No overt measles infections were noted. When disease activity in vaccinated patients (n = 108) was compared with activity in those not yet vaccinated (n = 86), there were no significant differences.
The MMR booster vaccination does not seem to aggravate disease activity in JIA. This indicates that the most patients with JIA can be vaccinated safely with the MMR vaccine. A prospective study is recommended.