Prevalence, incidence, and autoimmune comorbidities of celiac disease: a nation-wide, population-based study in Denmark from 1977 to 2016

AIM: The aim of this study was to describe and identify potential trends with respect to prevalence, incidence, age, sex, and autoimmune comorbidity of celiac disease (CD). PATIENTS AND METHODS: A Danish nationwide cohort study of CD using data from The National Patient Register. Patients with a primary or secondary diagnosis code of CD during the period 1977 to 2016 were identified. Information on sex, date of birth, death, or immigration was obtained from the Danish Civil Registration System, and autoimmune comorbidities were identified in the Danish National Patient Register. The CD cohort was compared with the general Danish population using a control cohort and aggregated data obtained from Statistics Denmark. RESULTS: The CD cohort consisted of 11 802 (65% women) patients. The median age at diagnosis of CD varied between 30 years in 1980-1984 and 45 years in 1995-1999 and 27 years in 2015-2016. The prevalence of CD in 1986 and 2016 was 14 and 180 per 100 000 persons, respectively, with a female/male ratio changing from 1.3 to 2.0. Incidence rates (per 100 000 person-years) changed from 1.6 in 1980-1984 to 15.2 in 2015-2016, with the largest increase among females aged 0-9 years. In 2016, prevalence of autoimmune comorbidities was 16.4% among the CD patients compared with 5.3% in the general population. CONCLUSION: The prevalence of diagnosed CD has doubled every decade in Denmark from 1986 to 2016, and in the same period the female/male ratio has increased and the median age at diagnosis has decreased. The prevalence of autoimmune comorbidity in 2016 was three times higher among CD patients compared with the general Danish population.