Initial nonresponders had an increased response rate after repeated questionnaire mailings

Background and 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. Conclusion: Repeated mailing of the questionnaire increased the effectiveness of follow-up among initial nonresponders. (c) 2005 Elsevier Inc. All rights reserved.