title: Response in individuals with and without foreign background and application to the National Cohort in Germany: which factors have an effect?
abstract: OBJECTIVE
  Response rates in epidemiologic studies vary widely. This study examines response rates of potential study participants according to foreign versus German background and investigates effects of recruitment strategies.
  
  
  METHODS
  Response rates and characteristics of recruitment procedures from feasibility studies for a large cohort study conducted in 2011 were analyzed.
  
  
  RESULTS
  Among 1,235 participants the proportion of recruited individuals with a foreign background was 17.3% (95% confidence interval 15.3-19.5%), significantly lower than in the sampling frame (23.1%). The difference between observed and expected proportion was high among individuals with Turkish background and smaller among ethnic Germans from the Former Soviet Union and other foreign background groups. Common recruitment strategies to increase the response had positive effects in all groups. For the planned recruitment strategy in the forthcoming German National Cohort, we estimate an overall response of approximately 50%.
  
  
  CONCLUSIONS
  Individuals with Turkish background may need particular efforts to be adequately represented in a population-based cohort in Germany. Other foreign background groups are relatively well represented using standard procedures. An adequate response can be obtained under carefully planned recruitment strategies.
authors.affiliation: Institut für Public Health, Universitätsklinikum Heidelberg, Heidelberg, Germany, Volker.Winkler@urz.uni-heidelberg.de.
authors.forename: Volker
authors.initials: V
authors.lastname: Winkler
authors.forename: Michael
authors.initials: M
authors.lastname: Leitzmann
authors.forename: Nadia
authors.initials: N
authors.lastname: Obi
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ahrens
authors.forename: Thomas
authors.initials: T
authors.lastname: Edinger
authors.forename: Guido
authors.initials: G
authors.lastname: Giani
authors.forename: Jakob
authors.initials: J
authors.lastname: Linseisen
authors.forename: Markus
authors.initials: M
authors.lastname: Löffler
authors.forename: Karin
authors.initials: K
authors.lastname: Michels
authors.forename: Ute
authors.initials: U
authors.lastname: Nöthlings
authors.forename: Sabine
authors.initials: S
authors.lastname: Schipf
authors.forename: Alexander
authors.initials: A
authors.lastname: Kluttig
authors.forename: H-Erich
authors.initials: HE
authors.lastname: Wichmann
authors.forename: Barbara
authors.initials: B
authors.lastname: Hoffmann
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Jöckel
authors.forename: Heiko
authors.initials: H
authors.lastname: Becher
mesh_terms: D015331:Cohort Studies; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D016021:Epidemiologic Studies; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D044382:Population Groups / Q000706:statistics & numerical data*; D012111:Residence Characteristics / Q000706:statistics & numerical data*