Celiac disease affects about 1% of the population, and seems to be increasing rather dramatically, according to recent studies. But a recent analysis of those studies calls that number into question.
Researchers writing in the Annals of Medicine conducted a review of published papers, and argued that celiac disease actually affects far fewer people than 1% of the population, and that the number of celiacs has been stable, not growing, for the past 20 years.
The researchers, led by Dr. Federico Biagi from the Coeliac Centre at the University of Pavia, Italy, looked at 40 studies on the incidence of celiac disease, and compared how those studies diagnosed the condition.
They found 32 papers used celiac antibody blood tests followed by endoscopy to diagnose celiac. In nine papers, EMA (anti-endomysial antibodies)-IgA tests -- considered the most sensitive blood tests -- were used for diagnosis. In four papers, meanwhile, tTG (anti-tissue transglutaminase)-IgA blood tests were used.
The tTG-IgA test can produce some false positives (i.e., will pick up people who then have a negative intestinal biopsy), but also can identify some celiacs who have negative results on the EMA test.
When the researchers excluded the studies relying solely on the tTG-IgA test and considered only the studies they considered the most reliable, they found a prevalence rate of 1 in 160 people, or about 0.6%.
"On the basis of our review, it emerges that in the last few years the prevalence of CD [celiac disease] in the general population has been over-estimated and that this was mainly due to the use (or should we write 'abuse'?) of the [tTG-IgA] as the only diagnostic tool," the researchers wrote.
However, not everyone agrees with Dr. Biagi and his colleagues. In a letter to the editor commenting on the paper, Ron Hoggan, Ed.D., a well-known celiac researcher, notes that Dr. Biagi's analysis missed several important studies showing a much higher rate of celiac disease in certain populations.
Dr. Hoggan argues that the prevalence of celiac disease probably is higher, not lower, than most researchers believe, in part because celiac blood tests don't identify everyone with the condition.
"Much of the evidence offered for over-estimation of celiac disease is more accurately seen as inducing under-estimations of this common ailment," Dr. Hoggan wrote.
I believe that using very strict diagnostic criteria for celiac disease -- such as requiring both a positive EMA-IgA and a positive biopsy for diagnosis -- winds up leaving people in the dark about whether gluten really is causing their health problems.
In fact, I'm pretty tired of listening to researchers (and, it should be noted, some celiacs) argue about who "really" has celiac disease.
If someone has significant health problems that are resolved by taking gluten out of his diet, his physicians should support that -- regardless of whether the person got a positive on the right blood test.
Too many people who don't pass the right tests are told that gluten isn't their problem when their health actually improves significantly off gluten. This argues for making the criteria used to diagnose celiac disease looser, not tighter as Dr. Biagi and his colleagues would do.
Source:
Biagi F. et al. Are we not over-estimating the prevalence of coeliac disease in the general population? Annals of Medicine, 2010; 42:557-561.
“In fact, I’m pretty tired of listening to researchers (and, it should be noted, some celiacs) argue about who “really” has celiac disease.
If someone has significant health problems that are resolved by taking gluten out of his diet, his physicians should support that — regardless of whether the person got a positive on the right blood test.”
AMEN!!