, according to a new report.
The overall high incidence among pediatric patients warrants a low threshold for screening and additional research on region-specific celiac disease triggers, the authors write.
“Determining the true incidence of celiac disease (CD) is not possible without nonbiased screening for the disease. This is because many cases occur with neither a family history nor with classic symptoms,” write Edwin Liu, MD, a pediatric gastroenterologist at the Children’s Hospital Colorado Anschutz Medical Campus and director of the Colorado Center for Celiac Disease, and colleagues.
“Individuals may have celiac disease autoimmunity without having CD if they have transient or fluctuating antibody levels, low antibody levels without biopsy evaluation, dietary modification influencing further evaluation, or potential celiac disease,” they write.
The study was published online in The American Journal of Gastroenterology.
Celiac disease incidence
The Environmental Determinants of Diabetes in the Young (TEDDY) study prospectively follows children born between 2004 and 2010 who are at genetic risk for both type 1 diabetes and CD at six clinical sites in four countries: the United States, Finland, Germany, and Sweden. In the United States, patients are enrolled in Colorado, Georgia, and Washington.
As part of TEDDY, children are longitudinally monitored for celiac disease autoimmunity (CDA) by assessment of autoantibodies to tissue transglutaminase (tTGA). The protocol is designed to analyze the development of persistent tTGA positivity, CDA, and subsequent CD. The study population contains various DQ2.5 and DQ8.1 combinations, which represent the highest-risk human leukocyte antigen (HLA) DQ haplogentotypes for CD.
From September 2004 through February 2010, more than 424,000 newborns were screened for specific HLA haplogenotypes, and 8,676 children were enrolled in TEDDY at the six clinical sites. The eligible haplogenotypes included DQ2.5/DQ2.5, DQ2.5/DQ8.1, DQ8.1/DQ8.1, and DQ8.1/DQ4.2.
Blood samples were obtained and stored every 3 months until age 48 months and at least every 6 months after that. At age 2, participants were screened annually for tTGA. With the first tTGA-positive result, all prior collected samples from the patient were tested for tTGA to determine the earliest time point of autoimmunity.
CDA, a primary study outcome, was defined as positivity in two consecutive tTGA tests at least 3 months apart.
In seropositive children, CD was defined on the basis of a duodenal biopsy with a Marsh score of 2 or higher. The decision to perform a biopsy was determined by the clinical gastroenterologist and was outside of the study protocol. When a biopsy wasn’t performed, participants with an average tTGA of 100 units or greater from two positive tests were considered to have CD for the study purposes.
As of July 2020, among the children who had undergone one or more tTGA tests, 6,628 HLA-typed eligible children were found to carry the DQ2.5, the D8.1, or both haplogenotypes and were included in the analysis. The median follow-up period was 11.5 years.
Overall, 580 children (9%) had a first-degree relative with type 1 diabetes, and 317 children (5%) reported a first-degree relative with CD.
Among the 6,628 children, 1,299 (20%) met the CDA outcome, and 529 (8%) met the study diagnostic criteria for CD on the basis of biopsy or persistently high tTGA levels. The median age at CDA across all sites was 41 months. Most children with CDA were asymptomatic.
Overall, the 10-year cumulative incidence was highest in Sweden, at 8.4% for CDA and 3% for CD. Within the United States, Colorado had the highest cumulative incidence for both endpoints, at 6.5% for CDA and 2.4% for CD. Washington had the lowest incidence across all sites, at 4.6% for CDA and 0.9% for CD.
“CDA and CD risk varied substantially by haplogenotype and by clinical center, but the relative risk by region was preserved regardless of the haplogenotype,” the authors write. “For example, the disease burden for each region remained highest in Sweden and lowest in Washington state for all haplogenotypes.”