1. Department of Gastroenterology; Complexo Hospitalario Universitario de Ourense; Ourense Spain
2. Department of Clinical Analysis; Complexo Hospitalario Universitario de Vigo; Vigo Spain
3. Department of Gastroenterology; Complexo Hospitalario Universitario de Vigo; Vigo Spain
4. Research Support Unit; Complexo Hospitalario Universitario de Ourense; Ourense Spain
5. Biodonostia Institute; Donostia Hospital; University of the Basque Country UPV/EHU, CIBERehd; San Sebastian Spain