Administrative information
Open Science
Introduction
Methods: Patient and public involvement, trial design
Methods: Participants, interventions, and outcomes
Methods: Assignment of interventions
Methods: Data collection, management, and analysis
Methods: Monitoring
Ethics
Data collection methods
Item 25b: Plans to promote participant retention and complete follow-up, including list of any outcome data to be collected for participants who discontinue or deviate from intervention protocols
Example
“Participant retention will be achieved by several strategies. Participant involvement throughout the trial development, activation and conduct, facilitated primarily by obtaining the Consumer Advisory Board’s input, ensures a patient-centred approach is applied to all trial activities and interactions with trial participants. The study staff at each site will be accessible to participants to answer their questions and respond to any concerns. To minimise the burden on a participant’s time, study visits will be scheduled to occur with any pre-existing clinic or other outpatient appointments in place for them when possible. Parking vouchers or travel reimbursements, to a maximum of $60 AUD, will be provided for visits that are study-specific and cannot be done remotely over the phone. Practical guidance and suggestions for participant retention awareness training will occur at the site initiation meetings and is documented in the Operations Manual.
For participants who withdraw from the trial, no further information will be collected from the date of withdrawal. If a participant at an intervention site does not receive the CGA [Comprehensive Geriatric Assessment intervention], or a participant at the control site receives a CGA, they will remain in the trial and be followed up until the end of the study and analyses will be conducted using the intention-to-treat principle ” [393].
Explanation
Trial investigators must often seek a balance between achieving a sufficiently long follow-up for clinically relevant outcome measurement [394], and a sufficiently short follow-up to decrease attrition and maximise completeness of data collection. Non-retention refers to instances where participants are prematurely “off-study” (i.e., consent withdrawn or lost to follow-up) and thus outcome data cannot be obtained from them. The majority of trials will have some degree of non-retention, and the number of these “off-study” participants usually increases with the duration of follow-up [395].
It is desirable to plan ahead for how retention will be promoted in order to prevent missing data and avoid the associated complexities in both the study analysis (Item 27c) and interpretation. Participant retention can be improved [206, 236, 396], e.g., by financial reimbursement, systematic methods and reminders for contacting patients, scheduling appointments, and monitoring retention, and limiting participant burden related to follow-up visits and procedures (Item 18).
Because missing data can be a major threat to trial validity and statistical power, data collection is often continued until a participant withdraws from the study [397]. A participant who discontinues follow-up assessment for one outcome may be willing to continue with assessments for other outcomes, if given the option.
Non-retention should be distinguished from non-adherence [398]. Non-adherence refers to deviation from intervention protocols (Item 15c), but does not mean that the participant is “off-study” and no longer in the trial. Non-adherence should not be an automatic reason for ceasing to collect data from the trial participant. It is widely recommended that all randomised participants be included in the analysis in their assigned groups, regardless of adherence (Item 27c).
Reviews of two samples of 108 and 292 trial protocols from 2016 found that only half reported strategies to promote participant retention and complete follow-up [9, 10].
Protocols should describe any retention strategies and define which outcome data will be recorded from non-adherers [236]. Protocols should also detail any plans to record the reasons for non-adherence (e.g., discontinuation of intervention due to harms versus lack of efficacy) and non-retention (i.e., withdrawn from trial or lost to follow-up), as this information can influence the handling of missing data and interpretation of results [236, 399].
Summary of key elements to address
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Retention strategies to promote complete follow-up and prevent missing data
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List of outcome data that will be collected for participants who discontinue or deviate from intervention protocols
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Any plans to record the reasons for:
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Non-adherence (e.g., discontinuation of intervention due to harms versus lack of efficacy)
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Non-retention (withdrawal from trial, loss to follow-up)
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