Feasibility and acceptance studies for the German National Cohort
From 2011 to 2013, the German National Cohort conducted pretest studies. The Department for Epidemiology used these studies to investigate the feasibility and methodological aspects of several potential research methods or instruments. We initiated a study on stool collection on-site, i.e. in the study centre, versus at home. Almost all participants opted for home collection (92%). Both participating study centres differed considerably in the proportion of on-site collection (2% - 14%). Regarding the home collection, 98% returned a sample. 
A second study on feasibility of biospecimen collection investigated the acceptance of cervicovaginal self-sampling. Of all eligible women 67% decided to take part in this study. Conducting a cervicovaginal lavage at home based on a short user manual was acceptable to 98%. Laboratory analysis confirmed HPV16 as the most common HPV genoytype (6/18 samples positive for HPV) .
A questionnaire for retrospective collection mostly on 12-month prevalence of common infectious diseases was tested twice. In pretest 1, completeness, comprehensiveness and inter-item correlation was evaluated.  In pretest 2, new items on infection vulnerability and test-retest reliability were assessed. The weighted kappa ranged from 0.65 to 0.9. 
Prospective web-based data collection on common acute infections was also tested twice. In pretest 1, 167 GNC participants of 200 possible agreed to take part, 86% of whom responded at least once to weekly email reminders over 23 study weeks.  In pretest 2, 78% of the total study population belonged to the group "very good compliance". 
Regarding data collection using the official vaccination certificate, a pretest study tested 3 invitation methods to optimise the response: The use of any reminder led to 89% bringing their vaccination certificates versus 81% of participants without a special reminder (p=0.06). Comparing certificates with documentation of general practitioners showed that e.g. influenza vaccination is less often (7% - 36%) whereas single tetanus vaccination is more often (15% - 8%) recorded in the certificates. 
LEIBNIZ INSTITUTE FOR PREVENTION RESEARCH AND EPIDEMIOLOGY-BIPS, BREMEN, GERMANY
- Department of Epidemiological Methods and Etiologic Research
GERMAN CANCER RESEARCH CENTER, HEIDELBERG, GERMANY
- Division of Genome Modifications and Carcinogenesis, Research Program Infection and Cancer
- Division of Cancer Epidemiology
ROBERT KOCH-INSTITUTE, BERLIN, GERMANY
- Department for Infectious Disease Epidemiology
CHARITÉ - UNIVERSITÄETSMEDIZIN BERLIN, BERLIN, GERMANY
- Clinic for Gynecology· Institute for Social Medicine, Epidemiology and Health Economics
UNIVERSITY MEDICAL CENTER HAMBURG-EPPENDORF, HAMBURG, GERMANY
- Department of Cancer Epidemiology, Clinical Cancer Registry· University Cancer Center Hamburg
UNIVERSITY MEDICAL CENTER FREIBURG, FREIBURG, GERMANY
- Institute for Prevention and Cancer Epidemiology
- Center for Chronic Immunodeficiency Department of Biometry, Epidemiology and Information Processing, WHO,
- Collaborating Centre for Research and Training in Veterinary Public Health, University of Veterinary Medicine Hannover, Hannover, Germany
MAX-DELBRÜCK-CENTER FOR MOLECULAR MEDICINE, BERLIN, GERMANY
- Molecular Epidemiology Research Group
TWINCORE CENTRE FOR EXPERIMENTAL AND CLINICAL INFECTION RESEARCH, HANNOVER, GERMANY
Head of Study Centre in Hannover
Dr. med. Yvonne Kemmling
1. Schultze A, Akmatov MK, Andrzejak M, Karras N, Kemmling Y, Maulhardt A, Wieghold S, Ahrens W, Günther K, Schlenz H, Krause G, et al. Comparison of stool collection on site versus at home in a population-based study : feasibility and participants' preference in Pretest 2 of the German National Cohort. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2014;57(11):1264-9.
2. Castell S, Krause G, Schmitt M, Pawlita M, Delere Y, Obi N, Flesch-Janys D, Kemmling Y, Kaufmann AM. Feasibility and acceptance of cervicovaginal self-sampling within the German National Cohort (Pretest 2). Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2014;57(11):1270-6.
3. Sievers C, Akmatov MK, Kreienbrock L, Hille K, Ahrens W, Gunther K, Flesch-Janys D, Obi N, Michels KB, Fricke J, Greiser KH, et al. Evaluation of a questionnaire to assess selected infectious diseases and their risk factors : findings of a multicenter study. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2014;57(11):1283-91.
4. Castell S, Akmatov MK, Obi N, Flesh-Janys D, Nieters A, Kemmling Y, Pessler F, Krause G. Test-retest reliability of an infectious disease questionnaire and evaluation of self-assessed vulnerability to infections : findings of Pretest 2 of the German National Cohort. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2014;57(11):1300-7.
5. Mall S, Akmatov MK, Schultze A, Ahrens W, Obi N, Pessler F, Krause G. Web-based questionnaires to capture acute infections in long-term cohorts : findings of a feasibility study. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2014;57(11):1308-14.
6. Akmatov MK, Rübsamen N, Schultze A, Kemmling Y, Obi N, Günther K, Ahrens W, Pessler F, Krause G, Mikolajczyk RT. Diverse recruitment strategies result in different participation percentages in a web-based study, but in similar compliance. International journal of public health. 2015;60(8):937-43.
7. Schultze A, Akmatov MK, Castell S, Karch A, Ahrens W, Gunther K, Schlenz H, Flesch-Janys D, Obi N, Pessler F, Krause G. Collection of vaccination data in the German National Cohort : Findings of a feasibility study in three study centers. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2014;57(11):1292-9.
Prof. Dr. Gérard Krause
Head of Department for Epidemiology
Dr. Stefanie Castell
Deputy Head of Department for Epidemiology
- Epidemiologie - Prof. Dr. Gérard Krause
Geldgeber / Förderer
BMBF - Bundesministerium für Bildung und Forschung