title: Initial nonresponders had an increased response rate after repeated questionnaire mailings.
abstract: OBJECTIVE
  There is a growing evidence base on methods to improve response rates in surveys among patients. This study aimed to determine the additional effect of two intensive follow-up procedures compared to a simple follow-up procedure.
  
  
  METHODS
  Randomized controlled trial that compared repeated mailing of the questionnaire and a request to explain nonparticipation with a simple reminder card. The study population comprised 955 elderly adults registered with 26 general practitioners in The Netherlands.
  
  
  RESULTS
  A total of 530 adults (56%) returned the questionnaire within 3 weeks and a total of 640 (67%) after follow-up. Repeated mailing of the questionnaire had additional effect compared to the simple reminder card in the group of initial nonresponders (relative risk=1.60, 95% confidence interval: 1.11-2.31), but not regarding the overall response rate. A request to explain nonparticipation did not have additional effect.
  
  
  CONCLUSIONS
  Repeated mailing of the questionnaire increased the effectiveness of follow-up among initial nonresponders.
authors.affiliation: Centre for Quality of Care Research (WOK), Radboud University Nijmegen Medical Centre, P.O. Box 9101, Nijmegen 6500, The Netherlands. M.Wensing@kwazo.umcn.nl
authors.forename: Michel
authors.initials: M
authors.lastname: Wensing
authors.forename: Geert
authors.initials: G
authors.lastname: Schattenberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005194:Family Practice; D005260:Female; D006801:Humans; D008297:Male; D010358:Patient Participation; D011159:Population Surveillance / Q000379:methods*; D011177:Postal Service; D017010:Reminder Systems; D015983:Selection Bias; D011795:Surveys and Questionnaires