The Danish Health and Wellbeing Survey: Study design, response proportion and respondent characteristics

Aims: This study aimed to describe the study design and respondent characteristics (including non-response analyses) of the Danish Health and Wellbeing Surveys in 2015 and 2019 and a follow-up survey that was carried out during the COVID-19 pandemic in 2020. Methods: The Danish Health and Wellbeing Survey is the Danish part of the European Health Interview Survey (EHIS). The samples in 2015 (N=12,000) and 2019 (N=14,000) were both based on a simple random selection of individuals aged > 15 years from the Danish Civil Registration System. All individuals from the sample in 2019 who were still alive and living in Denmark were reinvited for a follow-up survey in 2020 (N=13,474). Data in all surveys were collected via self-administered questionnaires (web or paper based). The questionnaires in 2015 and 2019 included the EHIS model questionnaire as well as national questions, whereas the questionnaire in 2020 mainly focused on physical and mental health, employment and working lives, and health behaviour. Results: The overall response proportion declined slightly between 2015 (48.4%) and 2019 (47.4%) but went up to 49.8% in the follow-up survey in 2020. Unit non-response was associated with, for example, male sex, younger age, being unmarried and lower educational level but not with degree of urbanisation. In all, 5000 individuals completed the questionnaire in both 2019 and 2020. Conclusions: The results are in line with most previous research on non-response in health surveys. However, an association between degree of urbanisation and non-response has been suggested in previous studies. This association was not found in our study.