1149 Osteoprotegerin Expression is Upregulated in the Colon of Children With Active Inflammatory Bowel Disease

Abstract

Background: Inflammatory Bowel Diseases (IBD) are chronic, relapsing conditions. Infections and other environmental exposures that vary by season have been postulated to trigger relapses; however, little information has been published on the seasonality of pediatric-onset IBD. Further understanding of this topic may provide valuable data on the epidemiology of Crohn's Disease (CD) and Ulcerative Colitis (UC). Aim: To examine whether season is associated with disease activity in pediatric-onset IBD. Methods: ImproveCareNow (ICN) is a multicenter network of health care providers formed in 2007 to improve the quality of care of children with IBD. The ICN registry contains disease and treatment data, including physician global assessment (PGA), prospectively collected during outpatient encounters. This study analyzed data collected from December 2008-November 2010 at 12 centers across the USA. The percentage of visits during each season in which patients were classified as being in remission based on PGA was calculated. For patients with multiple visits per season, only the visit with the most severe PGA score was included. The distribution of sick visits (PGA of mild, moderate, or severe) and well visits (PGA of remission) across each season was also calculated. Seasons were defined as summer (Jun-Aug), fall (Sep-Nov), winter (Dec-Feb), and spring (Mar-May). Data was further divided into northern and southern regions (defined by 37° latitude). A generalized linear mixed model and the multinomial chi-square test were used for statistical analysis with p<0.05 considered significant. Results: The percentage of UC visits (n=1129)in remission was highest in summer and lowest in winter (summer 51.6%, fall 48.8%, spring 45.0%, winter 41.9%) with significant seasonal variation (p=0.01). A similar pattern was seen in CD (summer 51.4%, fall 47.5%, winter 46.9%, spring 45.8%, n=2937), though not statistically significant (p=0.09). The results were consistent across the northern and southern regions (UC p=0.58, CD p=0.08). The percentage of all sick visits was evenly distributed across seasons for UC (n=954, p=0.81) and CD (n=2414, p=0.07). However, the percentage of well visits was highest in the summer and lowest in the winter in both UC (28.7% vs. 20.5%, n=1440, p<0.001) and CD (28.1% vs. 22.6%, n=3688, p<0.001). Conclusion: In this large multicenter study, seasonal variation of disease activity was not found, nor was there seasonal variation when examined by region. Although the percentage of visits of UC patients in remission increased during the summer, this was due to a higher percentage of all well visits during this season. One potential explanation is that well visits may be intentionally scheduled during summer months to limit the amount of school missed by children.