Abstract
Background: There is uncertainty about the effects of modifications to trial patient invitation letters on recruitment and retention. However, such documents are important.
Methods: A 2x2 factorial design embedded a pair of randomised Studies Within a Trial (SWAT) within a large host trial (CLEAR), to evaluate the effects of including wet-ink signatures and photographs in the patient invitation letter. Patients were randomised to receive one of four invitation letters: with a wet-ink or generic signature, and with or without a photograph. The primary outcome was the proportion of invited patients who joined the CLEAR trial. The secondary outcome was the proportion of patients retained in the trial.
Results: 368 letters were given to potential participants in the CLEAR trial and 121 (33%) joined. Proportions for each randomised group were generic signature and no photograph: 38% (33/88); generic signature and photograph: 32% (28/88); wet-ink personal signature and no photograph: 29% (26/91); wet-ink personal signature and photograph: 34% (34/101). There was no evidence of a significant difference in recruitment between those receiving the patient invitation letter containing a wet-ink versus generic signature (odds ratio (OR): 0.86, 95% confidence intervals (CI): 0.55 to 1.32, p=0.49) or photograph versus no photograph (OR: 0.99, 95% CI: 0.64 to 1.53, p=0.97). Retention was similar for the wet-ink and generic signature groups (OR: 1.20, 95% CI: 0.35 to 4.16, p=0.77) but significantly better when a photograph was used (OR: 5.40, 95% CI: 1.12 to 26.15, p=0.04, based on 2 withdrawals in the photograph group versus 9 in the no photograph group).
Conclusions: These SWAT add to the evidence base for the effects of modifications to clinical trial documentation on recruitment and retention. We found including a photograph may improve retention. Although these analyses are underpowered, they will contribute to meta-analysis of similar comparisons.
Methods: A 2x2 factorial design embedded a pair of randomised Studies Within a Trial (SWAT) within a large host trial (CLEAR), to evaluate the effects of including wet-ink signatures and photographs in the patient invitation letter. Patients were randomised to receive one of four invitation letters: with a wet-ink or generic signature, and with or without a photograph. The primary outcome was the proportion of invited patients who joined the CLEAR trial. The secondary outcome was the proportion of patients retained in the trial.
Results: 368 letters were given to potential participants in the CLEAR trial and 121 (33%) joined. Proportions for each randomised group were generic signature and no photograph: 38% (33/88); generic signature and photograph: 32% (28/88); wet-ink personal signature and no photograph: 29% (26/91); wet-ink personal signature and photograph: 34% (34/101). There was no evidence of a significant difference in recruitment between those receiving the patient invitation letter containing a wet-ink versus generic signature (odds ratio (OR): 0.86, 95% confidence intervals (CI): 0.55 to 1.32, p=0.49) or photograph versus no photograph (OR: 0.99, 95% CI: 0.64 to 1.53, p=0.97). Retention was similar for the wet-ink and generic signature groups (OR: 1.20, 95% CI: 0.35 to 4.16, p=0.77) but significantly better when a photograph was used (OR: 5.40, 95% CI: 1.12 to 26.15, p=0.04, based on 2 withdrawals in the photograph group versus 9 in the no photograph group).
Conclusions: These SWAT add to the evidence base for the effects of modifications to clinical trial documentation on recruitment and retention. We found including a photograph may improve retention. Although these analyses are underpowered, they will contribute to meta-analysis of similar comparisons.
| Original language | English |
|---|---|
| Number of pages | 12 |
| Journal | F1000Research |
| Volume | 11 |
| Issue number | 174 |
| DOIs | |
| Publication status | Published online - 11 Feb 2022 |
Bibliographical note
Copyright: This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Data Availability Statement
Underlying dataZenodo: underlying data. https://doi.org/10.5281/zenodo.5792978 (Anand, 2021a).
Extended data
Zenodo: Invitation letters design. https://doi.org/10.5281/zenodo.5654301 (Anand, 2021b)
Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).
Funding
Medical Research Council (MR/R013748/1) National Institute for Health Research (15/100/01) Grant Information: This SWAT research was funded by the Medical Research Council PROMoting THE USE of SWATs (PROMETHEUS) Award (Grant number MR/R013748/1). Grant assigned to Professor Judy Bradley. The CLEAR trial is funded by the National Institute for Health Research, Health Technology Assessment Programme (15/100/01). We also acknowledge the Professor John Glover Award for supporting the work of Rohan Anand. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
UN SDGs
This output contributes to the following UN Sustainable Development Goals (SDGs)
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SDG 3 Good Health and Well-being
Keywords
- SWAT
- Study Within a Trial
- Methodology
- Recruitment
- Retention
- Randomised trial
- Patient invitation letter
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