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. Author manuscript; available in PMC: 2017 Nov 20.
Published in final edited form as: J Clin Epidemiol. 2017 May 22;88:122–132. doi: 10.1016/j.jclinepi.2017.05.010

Table 3.

Best practice guidance for the use of retention strategies in RCTs

Retention strategy Guidance for the use of retention strategies in RCTs Barrier to implementation
Incentives

  • Financial incentives valued £5–£20 can be considered to improve questionnaire response

  • Small benefit gained from adding incentives

  • Additional administration involved in sending monetary incentives to RCT participants

  • Nonmonetary incentives can be considered as a token of appreciation for RCTs participants with careful consideration of appropriate branding

  • None identified
Communication strategies

  • Second-class post can be used for routine postal communication with RCT participants

  • None identified
New questionnaire formats

  • Alternative ways to complete outcome data, for example, by post, text, or e-mail can be used to improve response

  • None identified

  • A relevant and validated questionnaire should be used to measure RCT outcomes

  • None identified

  • Plain English should be used in questionnaires

  • None identified

Abbreviation: RCT, randomized clinical trial.