Three behavior change theory–informed randomized studies within a trial to improve response rates to trial postal questionnaires

Beatriz Goulao* (Corresponding Author), Anne Duncan, Ruth Floate, Jan Clarkson, Craig Ramsay

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
7 Downloads (Pure)


OBJECTIVE: Our aim was to design and evaluate a novel behaviour change approach to increase response rates to an annual postal questionnaire in three randomised Studies within a Trial (SWATs) and replicate the most promising SWAT.

STUDY DESIGN AND SETTING: SWAT1 tested a trial logo sticker on questionnaire envelopes vs no sticker; SWAT2 tested a theoretically informed letter sent with the questionnaire versus a standard letter; SWAT3 tested a theoretically informed newsletter sent prior to the questionnaire versus no newsletter. The SWATs were conducted within a large dental trial (N=1,877 adults) and SWAT2 replicated in a different trial in a similar setting (N=2,372).

RESULTS: SWAT1 improved response rates by 1.4%, 95% confidence interval (CI) (-7.2%, 10.0%). SWAT2 improved response rates by 7.0%, 95% CI (1.7%, 12.3%). SWAT3 improved response rates by 0.8%, 95% CI (-5.1%, 6.7%). Replication of SWAT2 as the most promising SWAT showed improvement in response rates of 1.0%, 95% CI (-3.2%, 5.3%). Pooled results from SWAT2 showed an overall improvement in response rates of 3.4%, 95% CI (0.1%, 6.7%).

CONCLUSION: A theory-based behavioural approach to design interventions to improve trial response rates showed small, but meaningful improvements. The approach presented here can be easily implemented and adapted to address other identified barriers to trial retention.

Original languageEnglish
Pages (from-to)35-41
Number of pages7
JournalJournal of Clinical Epidemiology
Early online date4 Feb 2020
Publication statusPublished - Jun 2020

Bibliographical note

IQuaD was funded by the NIHR HTA (project 09/01/45). INTERVAL was funded by the NIHR HTA (project 06/35/99). No additional funding was obtained to conduct the randomised studies with the trials. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. The Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates.


  • Attrition
  • Behavioural intervention
  • Dentistry
  • Randomized controlled trials
  • Retention
  • Study within a trial
  • Theoretical Domains Framework


Dive into the research topics of 'Three behavior change theory–informed randomized studies within a trial to improve response rates to trial postal questionnaires'. Together they form a unique fingerprint.

Cite this