The requirement for prior consent to participate on survey response rates: a population-based survey in Grampian

A two-stage survey was carried out consistent with new confidentiality guidelines. Individuals were contacted by post and asked by the Director of Public Health to consent to receive a postal or electronic questionnaire about communicating their views to the NHS. Those who consented were then sent questionnaires. Response rates at both stages were measured.25% of people returned signed consent forms and were invited to complete questionnaires. Respondents at the consent stage were more likely to be female (odds ratio (OR) response rate of women compared to men = 1.5, 95% CI 1.4, 1.7), less likely to live in deprived postal areas (OR = 0.59, 95% CI 0.45, 0.78) and more likely to be older (OR for people born in 1930–39 compared to people born in 1970–79 = 2.82, 95% CI 2.36, 3.37). 80% of people who were invited to complete questionnaires returned them. Response rates were higher among older age groups. The overall response rate to the survey was 20%, relative to the original number approached for consent (1951/10000).The requirement of a separate, prior consent stage may significantly reduce overall survey response rates and necessitate the use of substantially larger initial samples for population surveys. It may also exacerbate non-response bias with respect to demographic variables.Accurate information on population characteristics and healthcare needs is an essential pre-requisite for informed healthcare decision making. There are a number of ways of eliciting this population-level information; one of the most common being self-completion questionnaire surveys. Self-completion surveys have been used with significant success in a number of fields; for example, to elicit information on lifestyle, occupation and health. A substantial review of published surveys is provided by McColl et al. [1]. Self-completion questionnaires have been used widely in epidemiological and community health studies and they are also potentially important to ascertain public opinion relati