1 Department of Otorhinolaryngology-Head and Neck Surgery, University of Helsinki and Helsinki University Hospital, P.O. Box 263, 00029, Helsinki, Finland. pia.jarvenpaa@fimnet.fi.
2 Department of Gastroenterology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
3 Department of Otorhinolaryngology-Head and Neck Surgery, University of Helsinki and Helsinki University Hospital, P.O. Box 263, 00029, Helsinki, Finland.