The incidence of coeliac disease in adult first degree relatives

Background and aimsAlthough prevalence of coeliac disease among first degree relatives of coeliac patients is well-known, only four studies are available about its incidence. We investigated whether first degree relatives found to be negative at a first serological screening can subsequently develop coeliac disease.Patients and methodsIn the last 6 years, endomysial antibodies were tested in 158 adult first degree relatives referred to our coeliac out-patient clinic. After at least a year, negative subjects were offered a second testing. Sixty-three accepted.Results130/158 first degree relatives tested negative initially. Although one of them had developed coeliac disease after the first testing, at the second testing none of the 63 endomysial antibody negative first degree relatives proved positive. Incidence of coeliac disease among first degree relatives was 1/64 in 51 months, 0.437% year (95%CI 0.05–2.62). An analysis of the sample size showed that 10,000 first degree relatives must be followed up to significantly reduce the CI.ConclusionsAlthough we confirmed the high prevalence of coeliac disease among first degree relatives (28/158, 17.7%), we found that the low incidence suggests that further studies are required to understand whether endomysial antibody negative first degree relatives need to be followed up.