Translation of questionnaire increases the response rate in immigrants: filling the language gap or feeling of inclusion?

Sweden has a long history of conducting questionnaire-based Public Health Surveys (PHS) to monitor health determinants. As Sweden has become a multi-ethnic society a linguistically adapted instrument to collect data was first used in Stockholm PHS 2006 to overcome the barrier of lack of Swedish language proficiency, but more importantly to overcome the psychological barrier of being excluded. The questionnaire was translated into the six most spoken languages among Swedish immigrants, namely Arabic, English, Farsi, Finnish, Spanish, and Turkish. In spite of a decrease in participation rate (-2.9%, p < 0.0001) among native Swedes in PHS 2006 compared with PHS 2002, there was a substantial increase in participation rate among immigrants in PHS 2006 who received a translated questionnaire or were interviewed in their mother tongue. The increase in response rate varied from 2.1% among Finnish-speaking immigrants up to 12.4% among Turkish-speaking immigrants and was significant for Arabic-speaking (p < 0.0001), Farsi-speaking (p = 0.003), Spanish-speaking (p < 0.0001) and Turkish-speaking (p < 0.0001) immigrants. Various attempts to increase participation rate will be of importance to policy makers involved in the integration of the immigrant population, to healthcare professionals, and obviously to the public.