title: Digital questionnaire platform in the Danish Blood Donor Study.
abstract: OBJECTIVE
  The Danish Blood Donor Study (DBDS) is a prospective, population-based study and biobank. Since 2010, 100,000 Danish blood donors have been included in the study. Prior to July 2015 all participating donors had to complete a paper-based questionnaire. Here we describe the establishment of a digital tablet-based questionnaire platform implemented in blood bank sites across Denmark.
  
  
  METHODS
  The digital questionnaire was developed using the open source survey software tool LimeSurvey. The participants accesses the questionnaire online with a standard SSL encrypted HTTP connection using their personal civil registration numbers. The questionnaire is placed at a front-end web server and a collection server retrieves the completed questionnaires. Data from blood samples, register data, genetic data and verification of signed informed consent are then transferred to and merged with the questionnaire data in the DBDS database.
  
  
  RESULTS
  The digital platform enables personalized questionnaires, presenting only questions relevant to the specific donor by hiding unneeded follow-up questions on screening question results. New versions of questionnaires are immediately available at all blood collection facilities when new projects are initiated.
  
  
  CONCLUSIONS
  The digital platform is a faster, cost-effective and more flexible solution to collect valid data from participating donors compared to paper-based questionnaires. The overall system can be used around the world by the use of Internet connection, but the level of security depends on the sensitivity of the data to be collected.
authors: Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. Electronic address: kristoffer.soelvsten.burgdorf@regionh.dk.
authors: K S
authors: KS
authors: Burgdorf
authors: Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, Copenhagen University Hospital, Roskilde, Denmark.
authors: N
authors: N
authors: Felsted
authors: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors: S
authors: S
authors: Mikkelsen
authors: Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors: M H
authors: MH
authors: Nielsen
authors: Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors: L W
authors: LW
authors: Thørner
authors: Department of Clinical Immunology, Naestved Hospital, Naestved, Denmark.
authors: O B
authors: OB
authors: Pedersen
authors: Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors: E
authors: E
authors: Sørensen
authors: Department of Clinical Immunology, Aalborg University Hospital, Aalborg, Denmark.
authors: K R
authors: KR
authors: Nielsen
authors: Department of Clinical Immunology, Odense University Hospital, Odense, Denmark.
authors: M T
authors: MT
authors: Bruun
authors: Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, Copenhagen University Hospital, Roskilde, Denmark.
authors: T
authors: T
authors: Werge
authors: Department of Clinical Immunology, Aarhus University Hospital, Aarhus, Denmark.
authors: C
authors: C
authors: Erikstrup
authors: Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, Copenhagen University Hospital, Roskilde, Denmark.
authors: T
authors: T
authors: Hansen
authors: Department of Clinical Immunology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
authors: H
authors: H
authors: Ullum
mesh_terms: D001782:Blood Donors; D003718:Denmark; D005260:Female; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires
keywords: Blood donors; Data collection; Epidemiology; MeSH; Methods; Surveys and questionnaires