The Poster Hall at this week’s American College of Rheumatology annual meeting was the size of an aircraft carrier. How do you tackle a room like this without getting overwhelmed? I focused on the Juvenile Idiopathic Arthritis abstracts and picked out a dozen that were compelling to me. This first batch focuses on the etiology of JIA. If JIA follows a similar pattern to other autoimmune diseases, about a third of the blame lies with a genetic predisposition and two-thirds on environmental factors. Here are three intriguing studies looking at antibiotics, smoking and gluten/food allergies and their role as potential environmental factors in the development of JIA.
Abstract #929: Antibiotic Exposure and the Development of Juvenile Idiopathic Arthritis: A Population-Based Case-Control Study. Daniel Horton et al, University of Pennsylvania. *This abstract was presented at the pediatric rheumatology abstract session.
With the role of the microbiome increasingly implicated in the development of autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease, the authors set out to examine whether antibiotic exposure is associated with new diagnosis of JIA. This was a nested case-control study using data from The Health Improvement Network in the United Kingdom. Out of the more than 450,000 children in the database, they identified 152 cases of JIA (ranging in age from 1-15 years old). Controls were randomly matched by age and sex.
Data was collected on antibiotic exposure for both groups and analyzed with conditional logistic regression, adjusting for confounders and associated covariates. Results revealed that antibiotic exposure was more common in children with a new diagnosis of JIA. There was no change in this association when adjusted for infections. Having multiple treated URI’s was associated with the development of JIA but having multiple untreated URIs was not, implying that the antibiotic exposure might be more important than the infection itself. Controls were more likely to be unexposed to antibiotics while children with JIA were more likely to have had multiple courses of antibiotics. When a child had more than five prescriptions, the risk of new diagnosis increased by 3.5-fold.
The authors conclude that antibiotics are associated with the development of JIA and that these results suggest a possible role of antibiotics in pathogenesis of JIA. However, it’s important not to jump to conclusions. This is only one, small study and is limited by a predominance of young (ages 1-5) children, which may skew the data; by the 10% of the children excluded from the study; and by the limitations of the database itself. An alternate explanation for the association between antibiotics and JIA could be that children who are developing JIA have immune dysregulation and thus are more likely to get an infection/receive antibiotics. Regardless, the findings of this study will push researchers to continue investigating the role of antibiotics in JIA so expect to see more of this research coming down the pike.
Environmental Risk Factors and Development of Juvenile Idiopathic Arthritis. Shernoi et al, Seattle Children’s Hospital.
Smoking is an established risk factor for rheumatoid arthritis, but little is known about the environmental factors involved in the pathogenesis of JIA. This was a case-control study out of Seattle Children’s Hospital looking for potential environment triggers in JIA. A questionnaire was administered to 223 children with JIA along with 86 controls. Overall, approximately 5% of mothers smoked during pregnancy for both cases and controls. This was a negative study, with no association found between maternal smoking during pregnancy or at JIA symptom onset, infections in the first year of life, daycare attendance, household pets, urban residence or family stressors (death, divorce, move, new household pets, unemployment) and the development of JIA.
Abstract #2286: Food Allergy and Celiac Disease in Children with Juvenile Idiopathic Arthritis. Davis et al, Tufts Floating Hospital for Children.
The connection between the gastrointestinal tract and rheumatic disease is strong, with some gastrointestinal infections (salmonella, Whipples disease), rheumatic diseases (Crohns disease) and even celiac disease able to manifest as arthritis. To further investigate the connection between the gut and rheumatic disease, the authors assessed the risk of food allergy and celiac disease in a large population of children with JIA. Using data from the electronic medical records of children seen at Boston Children’s Hospital between 1993 and 2014, they identified the rates of food allergy and celiac disease in both the general population and in children with JIA.
Children with JIA had an increased risk of celiac disease, 1% vs 0.18% in the general population. Children with JIA also had a statistically significant increased risk of food allergies. Given how common dietary changes (e.g. eliminating gluten in the absence of celiac disease, elimination diets) are cited on the internet as an alternative “treatment” for JIA, its heartening that someone is looking into this association further. This study, however, does not help us understand how celiac/food allergies and JIA are connected – a cause, an effect, or an association with causation.
More to come but, in the meantime, you can find ALL the abstracts linked here.