Prevalence and characteristics of adults avoiding gluten without celiac disease: a long-term population-based follow-up study.

Objective: Nationwide prevalence studies on people avoiding gluten without celiac disease (PWAG) are lacking, and in particular, long-term follow-up studies are unavailable. We aimed to evaluate the prevalence, incidence, and characteristics of PWAG in a population-based cohort in 2000 and 2011.

Methods: Health and diet-related data were collected in nationwide Health 2000 and 2011 surveys, which comprised 5,777 and 3,866 individuals, respectively, representing 2,682,733 and 1,967,876 Finnish adults. Serum samples were taken for the measurement of transglutaminase autoantibodies. In total 3,296 individuals participated in both surveys, forming a prospective cohort. PWAG refers to subjects avoiding gluten without celiac disease or positive autoantibodies. Psychological health was assessed with General Health Questionnaire and the Beck Depression Inventory.

Results: The prevalence of PWAG increased significantly from 0.2% (2000) to 0.7% (2011) (p < 0.001), with the highest prevalence (1.3%) detected in individuals > 70 years old. An annual incidence rate of 42 (95% confidence interval 25-71) per 100,000 persons was noted. The PWAG group was more likely to maintain additional special diets than those not avoiding gluten, including e.g. lactose-free diet (41.7% vs. 12.0% in 2011, p < 0.001) and food restriction for allergy (12.5% vs. 3.0%, p = 0.007). Beck Depression Inventory indicated more depression (p = 0.023) among PWAG in 2000, while no difference was seen in 2011 or in General Health Questionnaire. Celiac disease-related risk factors, including female gender, anemia, autoimmune diseases or antibody levels near the upper limit of normal in 2000, did not predict later gluten avoidance.

Conclusions: The prevalence of PWAG multiplied over a decade, reaching 0.7% in 2011 in Finland. The PWAG group maintained more likely additional dietary restrictions than those not avoiding gluten and had signs of psychosocial burden. No predicting factors for the condition were identified.