[The German Health Interview and Examination Survey for Children and Adolescents (KiGGS): sample design, response and nonresponse analysis].

From May 2003 to May 2006, the Robert Koch Institute conducted the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). Aim of this nationwide interview and examination survey was to collect, for the first time, comprehensive and nationwide data on the health status of children and adolescents aged 0 to 17 years. Subject recruitment was carried out in two steps: first, 167 study locations (sample points) were chosen; second, subjects were selected from the official registers of residents of the local residents' registration offices. The percentage of quality-neutral drop-outs was comparatively low (5.3%). The participation rate was 66.6% and showed only little variation between age groups and sexes, but marked variation between resident aliens and Germans, between inhabitants of cities with a population of 100,000 or more and sample points with fewer inhabitants, as well as between the old West German states and the newly-formed German states (incl. Berlin). A total of 17,641 children and adolescents were surveyed, of whom 8,985 were boys and 8,656 were girls. The completeness of the data sets in relation to the modules was good. The main reasons for non-participation were failure to appear at an agreed appointment time (or cancellation of the appointment at short notice), the refusal of the child/adolescent himself, or lack of interest of the parents.