A group of Italian researchers suggests that prevalence may be closer to 1 in 160, but two recent studies were left out of review.
The Annals of Medicine recently published the editorial, "Are we not over-estimating the prevalence of coeliac disease in the general population?" A group of Italian researchers conducted a systematic review of 40 published journal articles, all of which focused on the prevalence of celiac disease in the general population. The authors took into consideration the sample sizes, years of publications, geographic regions, different types of publications and diagnostic criteria when conducting the review and then categorized the original papers based on their diagnostic criteria.
Biagi et al. (2010) observed that 32 of the 40 papers adhered to the proper diagnostic protocol of testing celiac antibodies followed by a small intestinal biopsy. The remaining 8 papers used only either a positive antibody test or a positive duodenal biopsy to support the diagnosis of celiac disease. In conclusion, the authors calculated a prevalence of 1 in 160, a prevalence lower than what is currently recognized (1 in 133).
Other findings: The prevalence remains the same among both adults and children, and the prevalence does not differ in different geographic regions.
Biagi et al. (2010) point to the use of the tTG blood test as the only tool used to support a diagnosis as reason for this overestimation. The authors note that the tTG's specificity of 99% (not 100%) might become problematic in populations with a low risk of celiac disease.
Note: It is important to note that two significant studies on the prevalence of celiac disease conducted in recent years were not included in this systematic review. These studies include Rubio-Tapia et al.'s (2009) finding that celiac had increased four-fold in the U.S. over the past 50 years, and Lohi et al.'s (2007) observation that the prevalence of celiac had doubled in Finland in two decades. Both Rubio-Tapia et al. (2009) and Lohi et al. (2007) concluded that environmental factors, such as exposure to wheat and the hybridization of wheat itself, may be responsible for the increase in prevalence. Further, Lohi et al. (2007) also noted that their findings could not be attributable to improved diagnostic tools and criteria.