Survey nonresponse among ethnic minorities in a national health survey--a mixed-method study of participation, barriers, and potentials.

Objectives: The participation rate in the Danish National Health Survey (DNHS) 2010 was significantly lower among ethnic minorities than ethnic Danes. The purpose was to characterize nonresponse among ethnic minorities in DNHS, analyze variations in item nonresponse, and investigate barriers and incentives to participation.

Design: This was a mixed-method study. Logistic regression was used to analyze nonresponse using data from DNHS (N = 177,639 and chi-square tests in item nonresponse analyses. We explored barriers and incentives regarding participation through focus groups and cognitive interviews. Informants included immigrants and their descendants of both sexes, with and without higher education.

Results: The highest nonresponse rate was for non-Western descendants (80.0%) and immigrants 25 (72.3%) with basic education. Immigrants and descendants had higher odds ratios (OR = 3.07 and OR = 3.35, respectively) for nonresponse than ethnic Danes when adjusted for sex, age, marital status, and education. Non-Western immigrants had higher item nonresponse in several question categories. Barriers to non-participation related to the content, language, format, and layout of both the questionnaire and the cover letter. The sender and setting in which to receive the questionnaire also influenced answering incentives. We observed differences in barriers and incentives between immigrants and descendants.

Conclusions: Nonresponse appears related to linguistic and/or educational limitations, to alienation generated by the questions' focus on disease and cultural assumptions, or mistrust regarding anonymity. Ethnic minorities seem particularly affected by such barriers. To increase survey participation, questions could be sensitized to reflect multicultural traditions, and the impact of sender and setting considered.