A study update newsletter or Post-it® note did not increase postal questionnaire response rates in a falls prevention trial: an embedded randomised factorial trial.

Sara Rodgers,David J Torgerson,Judith Watson,Caroline Fairhurst,Illary Sbizzera,Wesley Vernon,Catherine Hewitt,Sarah Cockayne,Sarah E Lamb

doi:10.12688/f1000research.14591.2

Abstract

Background: Participants not returning data collection questionnaires is a problem for many randomised controlled trials. The resultant loss of data leads to a reduction in statistical power and can result in bias. The aim of this study was to assess whether the use of a study update newsletter and/or a handwritten or printed Post-it® note sticker increased postal questionnaire response rates for participants of a randomised controlled trial. Method: This study was a factorial trial embedded within a host trial of a falls-prevention intervention among men and women aged ≥65 years under podiatric care. Participants were randomised into one of six groups: newsletter plus handwritten Post-it®; newsletter plus printed Post-it®; newsletter only; handwritten Post-it® only; printed Post-it® only; or no newsletter or Post-it®. The results were combined with those from previous embedded randomised controlled trials in meta-analyses. Results: The overall 12-month response rate was 803/826 (97.2%) (newsletter 95.1%, no newsletter 99.3%, printed Post-it® 97.5%, handwritten Post-it® 97.1%, no Post-it® 97.1%). The study update newsletter had a detrimental effect on response rates (adjusted odds ratio 0.14, 95% CI 0.04 to 0.48, p<0.01) and time to return the questionnaire (adjusted hazard ratio 0.86, 95% CI 0.75 to 0.99, p=0.04). No other statistically significant differences were observed between the intervention groups on response rates, time to response, and the need for a reminder. Conclusions: Post-it® notes have been shown to be ineffective in three embedded trials, whereas the evidence for newsletter reminders is still uncertain.

Highlights

Postal questionnaires represent a cost-effective and convenient way of collecting participant-reported outcome data in health research, such as in randomised controlled trials (RCTs)
Post-it® notes have been shown to be ineffective in three embedded trials, whereas the evidence for newsletter reminders is still uncertain
We present the results of a metaanalysis of the three ‘Post-it® notes’ and two ‘newsletters sent prior to questionnaires’ studies previously undertaken at York Trials Unit to increase questionnaire response rates in RCTs of health treatments

Summary

Introduction

Postal questionnaires represent a cost-effective and convenient way of collecting participant-reported outcome data in health research, such as in randomised controlled trials (RCTs). Attrition (i.e. when participants do not return the questionnaires) is a problem for many RCTs. The resultant loss of data leads to a reduction in statistical power and can result in bias[1]. A Cochrane systematic review[4] evaluating 110 different strategies to improve response rates to postal questionnaires in RCTs identified pre-notification as an effective strategy. One RCT has evaluated the effectiveness of a pre-notification newsletter to increase response rates[5]. This study found a statistically significant increase in response rates (OR 1.45, 95% CI 1.01 to 2.10) among participants allocated to receive the pre-notification newsletter. The aim of this study was to assess whether the use of a study update newsletter and/or a handwritten or printed Post-it® note sticker increased postal questionnaire response rates for participants of a randomised controlled trial. The results were combined with those from previous embedded randomised controlled trials in meta-analyses

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