Past studies have examined the serological screening process (blood test) for celiac disease and showed that while the autoimmune disease affects men and women equally, women are diagnosed more frequently. To date, it is not known what the diagnosis rate through serological testing is for black patients. In comparison with diagnosis rates in Northern and Western Europe, the United States has a high rate of undiagnosed celiac disease. To determine why this could be the case, researchers examined a nationwide database called the Clinical Outcomes Research Initiative (CORI) National Endoscopy Database, to learn how often biopsies of the duodenum (the first section of the intestine) are being performed.

The study examined duodenal biopsies performed in the U.S. between 2004 and 2009 in patients presenting with diarrhea, anemia, iron deficiency, or weight loss in which the upper GI tract appeared normal in an endoscopy, as this can be a common manifestation of celiac disease. Data from 13,091 individuals meeting these criteria were examined. 88 percent (11,489) of the patients were white and 58 percent (7,576) were females. The most common reason for the endoscopy was anemia, followed by diarrhea, weight loss, and iron deficiency. 66 percent (8,490) of these endoscopies were performed in a community or health maintenance organization (HMO) setting.

After examining the data, researchers discovered that the rate of biopsy increased each year from 35 percent in 2004 to 51 percent in 2009. It was noted that male patients, persons over 70 years old and patients of either black or Hispanic origin were least likely to have the biopsy. When examining age as a factor, it was found that biopsies occurred more frequently among patients aged 20-49. While this study shows biopsies occur more frequently in people aged 20-49, celiac is currently most often diagnosed in people aged 40-60, which dismisses the belief that celiac occurs among only children. Despite the increase in duodenal biopsies, the variations between the sexes and races remained.

Geographical information was also examined. Biopsy rates were highest in the Northwest (Oregon, Washington) and lowest in the North Central region (Indiana, Minnesota, Nebraska, North Dakota). It was also found that academic settings reported lower biopsy rates in comparison to Veteran Affairs or community/HMO medical settings.

The study reported limitations in the findings, as pathology and therefore the biopsy results were not taken into account, meaning the impact of nonperformance of the duodenal biopsy was not quantified. The four inclusion criteria were chosen as they are common presentations of celiac disease, but with numerous signs, symptoms and associated conditions indicative of the autoimmune condition, these do not include all possible manifestations. Race and ethnicity may also have been misclassified as these were reported by the conducting physicians and not the patients themselves.

Despite these study limitations, the researchers concluded it is less likely for patients who are male, black, Hispanic, or elderly to undergo a duodenal biopsy. Biopsy rates increased among all patient groups in the study over the years; however researchers say the reason for this increase is not clear. They hypothesize the increase could be attributed to a greater awareness of celiac disease, but it could also reflect the low biopsy rates as reported in a 2004 study. Researchers also noted that women are more likely to pursue medical care, which could account for the higher rates of diagnosis in females (a longstanding observation regarding the rate of diagnosis of celiac disease among females). The study investigators believe future efforts should focus on increasing the rate of duodenal biopsies in the “appropriate context.”

A recent study published in the American Journal of Gastroenterology on July 31, 2012 examined the prevalence rates of celiac in the U.S., including among the black and Hispanic populations. This study showed celiac to be rare in those races, but more common in non-Hispanic whites, affecting one percent of the population.

“The latest research shows that celiac disease is more common in Caucasians than in blacks or Hispanics, but celiac disease can occur in all of these groups, and it is important to make the diagnosis promptly when patients seek medical care, even if they belong to a ‘low risk’ group,” commented Benjamin Lebwohl, MD, MS, Assistant Professor of Clinical Medicine at the Celiac Disease Center at Columbia University and researcher in the duodenal biopsy and celiac diagnosis rate study.

The full study can be found in the U.S. National Library of Medicine on the National Institutes of Health website.