Use of strategies to improve retention in primary care randomised trials: a qualitative study with in-depth interviews

How do trial teams plan for retention during the design stage of the trial? A scoping review

BACKGROUND

Retention to trials is important to ensure the results of the trial are valid and reliable. The SPIRIT guidelines (18b) require "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" be included in trial protocols. It is unknown how often protocols report this retention information. The purpose of our scoping review is to establish if, and how, trial teams report plans for retention during the design stage of the trial.

MATERIALS AND METHODS

A scoping review with searches in key databases (PubMed, Scopus, EMBASE, CINAHL (EBSCO), and Web of Science from 2014 to 2019 inclusive) to identify randomised controlled trial protocols. We produced descriptive statistics on the characteristics of the trial protocols and also on those adhering to SPIRIT item 18b. A narrative synthesis of the retention strategies was also conducted.

RESULTS

Eight-hundred and twenty-four protocols met our inclusion criteria. RCTs (n = 722) and pilot and feasibility trial protocols (n = 102) reported using the SPIRIT guidelines during protocol development 35% and 34.3% of the time respectively. Of these protocols, only 9.5% and 11.4% respectively reported all aspects of SPIRIT item 18b "plans to promote participant retention and to complete follow-up, including list of any outcome data for participants who discontinue or deviate from intervention protocols". Of the RCT protocols, 36.8% included proactive "plans to promote participant retention" regardless of whether they reported using SPIRIT guidelines or not. Most protocols planned "combined strategies" (48.1%). Of these, the joint most commonly reported were "reminders and data collection location and method" and "reminders and monetary incentives". The most popular individual retention strategy was "reminders" (14.7%) followed by "monetary incentives- conditional" (10.2%). Of the pilot and feasibility protocols, 40.2% included proactive "plans to promote participant retention" with the use of "combined strategies" being most frequent (46.3%). The use of "monetary incentives - conditional" (22%) was the most popular individual reported retention strategy.

CONCLUSION

There is a lack of reporting of plans to promote participant retention in trial protocols. Proactive planning of retention strategies during the trial design stage is preferable to the reactive implementation of retention strategies. Prospective retention planning and clear communication in protocols may inform more suitable choice, costing and implementation of retention strategies and improve transparency in trial conduct.

Establishing Requirements for Technology to Support Clinical Trial Retention: Systematic Scoping Review and Analysis Using Self-determination Theory

BACKGROUND

Retaining participants in clinical trials is an established challenge. Currently, the industry is moving to a technology-mediated, decentralized model for running trials. The shift presents an opportunity for technology design to aid the participant experience and promote retention; however, there are many open questions regarding how this can be best supported. We advocate the adoption of a stronger theoretical position to improve the quality of design decisions for clinical trial technology to promote participant engagement.

OBJECTIVE

This study aimed to identify and analyze the types of retention strategies used in published clinical trials that successfully retain participants.

METHODS

A systematic scoping review was carried out on 6 electronic databases for articles published from 1990 to September 2020, namely CINAHL, The Cochrane Library, EBSCO, Embase, PsycINFO, and PubMed, using the concepts "retention," "strategy," "clinal trial," and "clinical research." This was followed by an analysis of the included articles through the lens of self-determination theory, an evidence-based theory of human motivation.

RESULTS

A total of 26 articles were included in this review. The motivational strategies identified in the clinical trials in our sample were categorized into 8 themes: autonomy; competence; relatedness; controlled motivation; branding, communication material, and marketing literature; contact, tracking, and scheduling methods and data collection; convenience to contribute to data collection; and organizational competence. The trials used a wide range of motivational strategies. Notably, the trials often relied on controlled motivation interventions and underused strategies to support intrinsic motivation. Moreover, traditional clinical trials relied heavily on human interaction and "relatedness" to support motivation and retention, which may cause problems in the move to technology-led decentralized trials. We found inconsistency in the data-reporting methods and that motivational theory-based approaches were not evident in strategy design.

CONCLUSIONS

This study offers direction and a framework to guide digital technology design decisions for future decentralized clinical trials to enhance participant retention during clinical trials. This research defines previous clinical trial retention strategies in terms of participant motivation, identifies motivational strategies, and offers a rationale for selecting strategies that will improve retention. It emphasizes the benefits of using theoretical frameworks to analyze strategic approaches and aid decision-making to improve the quality of technology design decisions.

Clinical and cost-effectiveness of paramedic administered fascia iliaca compartment block for emergency hip fracture (RAPID 2)-protocol for an individually randomised parallel-group trial

Background

Approximately 75,000 people fracture a hip each year in the UK. This painful injury can be devastating—with a high associated mortality rate—and survivors likely to be more dependent and less mobile. Pain relief at the scene of injury is known to be inadequate. Intravenous morphine is usually given by paramedics, but opioids are less effective for dynamic pain and can cause serious side effects, including nausea, constipation, delirium and respiratory depression. These may delay surgery, require further treatment and worsen patient outcomes. We completed a feasibility study of paramedic-provided fascia iliaca compartment block (FICB), testing the intervention, trial methods and data collection. The study (RAPID) demonstrated that a full trial was feasible. In this subsequent study, we aim to test safety, clinical and cost-effectiveness of paramedic-provided FICB as pain relief to patients with suspected hip fracture in the prehospital environment.

Methods

We will conduct a pragmatic multi-centre individually randomised parallel-group trial, with a 1:1 allocation between usual care (control) and FICB (intervention). Hospital clinicians in five sites (paired ambulance services and receiving hospitals) in England and Wales will train 220 paramedics to administer FICB. The primary outcome is change in pain score from pre-randomisation to arrival at the emergency department. One thousand four hundred patients are required to find a clinically important difference between trial arms in the primary outcome (standardised statistical effect ~ 0.2; 90% power, 5% significance). We will use NHS Digital (England) and the SAIL (Secure Anonymised Information Linkage) databank (Wales) to follow up patient outcomes using routine anonymised linked data in an efficient study design, and questionnaires to capture patient-reported outcomes at 1 and 4 months. Secondary outcomes include mortality, length of hospital stay, job cycle time, prehospital medications including morphine, presence of hip fracture, satisfaction, mobility, and NHS costs. We will assess safety by monitoring serious adverse events (SAEs).

Discussion

The trial will help to determine whether paramedic administered FICB is a safe, clinically and cost-effective treatment for suspected hip fracture in the pre-hospital setting. Impact will be shown if and when clinical guidelines either recommend or reject the use of FICB in routine practice in this context.

Trial registration

ISRCTN15831813. Registered on 22 September 2021.

From cohort to community: The emotional work of birthday cards in the Medical Research Council National Survey of Health and Development, 1946-2018

The Medical Research Council National Survey of Health and Development (NSHD) is Britain's longest-running birth cohort study. From their birth in 1946 until the present day, its research participants, or study members, have filled out questionnaires and completed cognitive or physical examinations every few years. Among other outcomes, the findings of these studies have framed how we understand health inequalities. Throughout the decades and multiple follow-up studies, each year the study members have received a birthday card from the survey staff. Although the birthday cards were originally produced in 1962 as a method to record changes of address at a time when the adolescent study members were potentially leaving school and home, they have become more than that with time. The cards mark, and have helped create, an ongoing evolving relationship between the NSHD and the surveyed study members, eventually coming to represent a relationship between the study members themselves. This article uses the birthday cards alongside archival material from the NSHD and oral history interviews with survey staff to trace the history of the growing awareness of importance of emotion within British social science research communities over the course of the 20th and early 21st centuries. It documents changing attitudes to science's dependence on research participants, their well-being, and the collaborative nature of scientific research. The article deploys an intertextual approach to reading these texts alongside an attention to emotional communities drawing on the work of Barbara Rosenwein.

Considerations for clinical trial design and conduct in the evaluation of novel advanced therapeutics in neurodegenerative disease

The recent advances in the development of potentially disease modifying cell and gene therapies for neurodegenerative disease has resulted in the production of a number of promising novel therapies which are now moving forward to clinical evaluation. The robust evaluation of these therapies pose a significant number of challenges when compared to more traditional evaluations of pharmacotherapy, which is the current mainstay of neurodegenerative disease symptom management. Indeed, there is an inherent complexity in the design and conduct of these trials at multiple levels. Here we discuss specific aspects requiring consideration in the context of investigating novel cell and gene therapies for neurodegenerative disease. This extends to overarching trial designs that could be employed and the factors that underpin design choices such outcome assessments, participant selection and methods for delivery of cell and gene therapies. We explore methods of data collection that may improve efficiency in trials of cell and gene therapy to maximize data sharing and collaboration. Lastly, we explore some of the additional context beyond efficacy evaluations that should be considered to ensure implementation across relevant healthcare settings.

Exploring Primary Care Clinicians' Views about How Best to Implement a Potential Trial around Point-of-Care Tests for Common Infections in South Africa

Optimisation of antibiotic prescribing is critical to combat antimicrobial resistance. Point-of-care tests (POCTs) for common infections could be a valuable tool to achieve this in primary care. Currently, their use has primarily been studied in high-income countries. Trials in low-and-middle-income countries face challenges unique to their setting. This study aims to explore the barriers and facilitators for a future trial of POCTs for common infections in South Africa. Twenty-three primary care clinicians in the Western Cape Metropole were interviewed. Interview transcripts were analysed using thematic analysis. We identified three key themes. These themes focused on clinicians’ views about proposed trial design and novel POCTs, clinicians’ perspectives about trial set-up, and specific trial procedures. Participants were overall positive about the proposed trial and POCTs. Potential issues centred around the limited space and technology available and participant retention to follow-up. Additionally, impact on clinic workload was an important consideration. These insights will be invaluable in informing the design of a feasibility trial of POCTs in this setting.

Surgical fixation compared with cast immobilisation for adults with a bicortical fracture of the scaphoid waist: the SWIFFT RCT

BACKGROUND

Scaphoid fractures account for 90% of carpal fractures and occur predominantly in young men. Immediate surgical fixation of this fracture has increased.

OBJECTIVE

To compare the clinical effectiveness and cost-effectiveness of surgical fixation with cast treatment and early fixation in adults with scaphoid waist fractures that fail to unite.

DESIGN

Multicentre, pragmatic, open-label, parallel two-arm randomised controlled trial with an economic evaluation and a nested qualitative study.

SETTING

Orthopaedic departments of 31 hospitals in England and Wales recruited from July 2013, with final follow-up in September 2017.

PARTICIPANTS

Adults (aged ≥ 16 years) presenting within 2 weeks of injury with a clear, bicortical fracture of the scaphoid waist on plain radiographs.

INTERVENTIONS

Early surgical fixation using Conformité Européenne-marked headless compression screws. Below-elbow cast immobilisation for 6-10 weeks and urgent fixation of confirmed non-union.

MAIN OUTCOME MEASURES

The primary outcome and end point was the Patient-Rated Wrist Evaluation total score at 52 weeks, with a clinically relevant difference of 6 points. Secondary outcomes included Patient-Rated Wrist Evaluation pain and function subscales, Short Form questionnaire 12-items, bone union, range of movement, grip strength, complications and return to work.

RESULTS

The mean age of 439 participants was 33 years; 363 participants were male (83%) and 269 participants had an undisplaced fracture (61%). The primary analysis was on 408 participants with valid Patient-Rated Wrist Evaluation outcome data for at least one post-randomisation time point (surgery, n = 203 of 219; cast, n = 205 of 220). There was no clinically relevant difference in the Patient-Rated Wrist Evaluation total score at 52 weeks: the mean score in the cast group was 14.0 (95% confidence interval 11.3 to 16.6) and in the surgery group was 11.9 (95% confidence interval 9.2 to 14.5), with an adjusted mean difference of -2.1 in favour of surgery (95% confidence interval -5.8 to 1.6; p = 0.27). The non-union rate was low (surgery group, n = 1; cast group, n = 4). Eight participants in the surgery group had a total of 11 reoperations and one participant in the cast group required a reoperation for non-union. The base-case economic analysis at 52 weeks found that surgery cost £1295 per patient more (95% confidence interval £1084 to £1504) than cast treatment. The base-case analysis of a lifetime-extrapolated model confirmed that the cast treatment pathway was more cost-effective. The nested qualitative study identified patients' desire to have a 'sense of recovering', which surgeons should address at the outset.

LIMITATION

There were 17 participants who had initial cast treatment and surgery for confirmed non-union, which in 14 cases was within 6 months from randomisation and in three cases was after 6 months. Three of the four participants in the cast group who had a non-union at 52 weeks were not offered surgery.

CONCLUSIONS

Adult patients with an undisplaced or minimally displaced scaphoid waist fracture should have cast immobilisation and suspected non-unions immediately confirmed and urgently fixed. Patients should be followed up at 5 years to investigate the effect of partial union, degenerative arthritis, malunion and screw problems on their quality of life.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN67901257.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 52. See the NIHR Journals Library website for further project information.

What are the most important unanswered research questions in trial retention? A James Lind Alliance Priority Setting Partnership: the PRioRiTy II (Prioritising Retention in Randomised Trials) study

BACKGROUND

One of the top three research priorities for the UK clinical trial community is to address the gap in evidence-based approaches to improving participant retention in randomised trials. Despite this, there is little evidence supporting methods to improve retention. This paper reports the PRioRiTy II project, a Priority Setting Partnership (PSP) that identified and prioritised unanswered questions and uncertainties around trial retention in collaboration with key stakeholders.

METHODS

This PSP was conducted in collaboration with the James Lind Alliance, a non-profit making initiative, to support key stakeholders (researchers, patients, and the public) in jointly identifying and agreeing on priority research questions. There were three stages. (1) First an initial online survey was conducted consisting of six open-ended questions about retention in randomised trials. Responses were coded into thematic groups to create a longlist of questions. The longlist of questions was checked against existing evidence to ensure that they had not been answered by existing research. (2) An interim stage involved a further online survey where stakeholders were asked to select questions of key importance from the longlist. (3) A face-to-face consensus meeting was held, where key stakeholder representatives agreed on an ordered list of 21 unanswered research questions for methods of improving retention in randomised trials.

RESULTS

A total of 456 respondents yielded 2431 answers to six open-ended questions, from which 372 questions specifically about retention were identified. Further analysis included thematically grouping all data items within answers and merging questions in consultation with the Steering Group. This produced 27 questions for further rating during the interim survey. The top 21 questions from the interim online survey were brought to a face-to-face consensus meeting in which key stakeholder representatives prioritised the order. The 'Top 10' of these are reported in this paper. The number one ranked question was 'What motivates a participant's decision to complete a clinical trial?' The entire list will be available at www.priorityresearch.ie .

CONCLUSION

The Top 10 list can inform the direction of future research on trial methods and be used by funders to guide projects aiming to address and improve retention in randomised trials.

Rapid Analgesia for Prehospital hip Disruption (RAPID): findings from a randomised feasibility study

Background

In managing hip fracture, effective pain relief before admission to hospital is difficult without risking side effects. Although emergency departments routinely use fascia iliaca compartment block (FICB), there has been little evaluation of its use by paramedics before hospital admission. We aimed to assess whether a multi-centre randomised trial to evaluate FICB was feasible.

Methods

Volunteer paramedics used scratchcards to allocate patients with hip fracture at random between FICB and pain relief as usual. Primary outcomes were mortality and quality of life. We also measured adverse events, costs, final diagnosis, length of stay in hospital, pain scores and quality of care and collected qualitative data about acceptability to patients in interviews, and paramedics in focus groups. We pre-specified criteria for deciding whether to progress to a fully powered trial based on the recruitment of paramedics and patients, delivery of FICB, retrieval of outcome data, safety, acceptability, and diagnostic accuracy of hip fracture.

Results

We effectively met all progression criteria: we recruited 19 paramedics who randomly allocated 71 patients between trial arms between 28 June 2016 and 31 July 2017; 57 (31 experimental arm, 26 usual care arm, 80% overall) retrospectively consented to follow-up. Just over half (17/31) of experimental participants received FICB; all others had contraindications, including nine taking anticoagulants. Four of the 31 participants assigned FICB and six of the 26 assigned usual care died within 6 months of hospital admission. Serious adverse events were also similar: 3/35 experimental versus 4/36 in usual care. Paramedics’ recognition of hip fracture had sensitivity of 49/64 (77%) with a positive predictive value of 46/57 (81%). We received quality of life questionnaires for 30 of 49 patients (61%) at 1 month and 12 of 17 (71%) at 6 months. Patient satisfaction was similar: experimental mean 3.4 (n = 20) versus 3.5 (n = 13) for usual care.

Conclusions

RAPID met all progression criteria within reasonable limits. As equipoise remains, we plan to undertake a fully powered multi-centre trial to test clinical and cost effectiveness of paramedic-administered FICB at the scene of hip fracture.

Trial registration

ISRCTN 60065373 sought 5 November 2015.

Electronic supplementary material

The online version of this article (10.1186/s40814-019-0454-1) contains supplementary material, which is available to authorized users.

Inclusion of special populations in clinical research: important considerations and guidelines

BACKGROUND

Trials that involve human participants call for experiments or observations that are performed in a clinical research setting. Currently, there are over 16,000 clinical trials open in the United States. Despite continuing efforts to include "special populations" in clinical trials, there are gaps in participation for people who are either minors or elderly adults, are from historically under-represented minorities, or live in rural communities. The inclusion of these special populations in clinical trials research is essential for conclusions that benefit all populations. Data suggest that study partic-ipation rates for special populations have fallen to levels that could endanger the successful performance of some types of research. This is particularly concerning in the 21st century, where demographic trends in the United States continue to shift towards an older and Hispanic population with fewer rural dwellers. Trends in New Mexico and other minority-majority states mirror many of these shifts.

RELEVANCE FOR PATIENTS

In this review, we highlight improvement strategies for enhanced clinical trial participation by members of special populations. Key drivers for disparate clinical trials participation and outcomes often include differences in genetics, physiology, and perceptions of mistrust towards researchers. To overcome these barriers, we focus on best practices in recruitment strategies from the perspectives of the participants, the researchers and the institutions that support clinical trials.

Interventions to improve retention in a surgical, clinical trial: A pragmatic, stakeholder-driven approach

OBJECTIVE

To explore stakeholder perspectives upon participant retention in clinical trials, and to generate strategies to support retention in a surgical, clinical trial.

STUDY DESIGN AND SETTING

The SWIFFT trial is a multicenter study comparing treatments for the fracture of the waist of the scaphoid bone in adults. Here we report upon a multistage, iterative consultative process with SWIFFT stakeholders, these include workshops with members of the public, with nurses involved in data collection, and with consultant clinicians. Structured discussions were digitally recorded and transcribed, data were handled and analyzed following a framework approach to qualitative data analysis.

RESULTS

Removing practical barriers were identified as important factors in supporting retention. Stakeholders also identified that (i) how well a study is understood and (ii) how much it is valued are important factors in an individual's willingness to maintain their involvement. A number of strategies resulted from this consultation, these include: in-clinic data collection, co-ordinated clinical and research appointments, a SWIFFT website, and newsletter.

CONCLUSION

A participatory approach to trial retention might engage all relevant stakeholders in the delivery of a clinical trial, it might also support the generation of specific and contextually relevant solutions to the challenge of participant retention.

A feasibility study of a novel, task-specific movement training intervention for women with patellofemoral pain

OBJECTIVE

To investigate whether a novel, task-specific training intervention that focused on correcting pain-producing movement patterns was feasible and whether it would improve hip and knee kinematics, pain, and function in women with patellofemoral pain.

DESIGN

Prospective, non-randomized, within-group, double baseline, feasibility intervention study.

SUBJECTS

A total of 25 women with patellofemoral pain were enrolled.

INTERVENTION

The intervention, delivered 2×/week for six weeks, consisted of supervised, high-repetition practice of daily weight-bearing and recreational activities. Activities were selected and progressed based on participants' interest and ability to maintain optimal alignment without increasing pain.

MAIN MEASURES

Primary feasibility outcomes were recruitment, retention, adherence, and treatment credibility (Credibility/Expectancy Questionnaire). Secondary outcomes assessing intervention effects were hip and knee kinematics, pain (visual analog scale: current, average in past week, maximum in past week), and function (Patient-Specific Functional Scale).

RESULTS

A total of 25 participants were recruited and 23 were retained (92% retention). Self-reported average daily adherence was 79% and participants were able to perform their prescribed home program correctly (reduced hip and knee frontal plane angles) by the second intervention visit. On average, treatment credibility was rated 25 (out of 27) and expectancy was rated 22 (out of 27). Hip and knee kinematics, pain, and function improved following the intervention when compared to the control phase.

CONCLUSION

Based on the feasibility outcomes and preliminary intervention effects, this task-specific training intervention warrants further investigation and should be evaluated in a larger, randomized clinical trial.

Best practice guidance for the use of strategies to improve retention in randomized trials developed from two consensus workshops

Objectives

To develop best practice guidance for the use of retention strategies in randomized clinical trials (RCTs).

Study Design and Setting

Consensus development workshops conducted at two UK Clinical Trials Units. Sixty-six statisticians, clinicians, RCT coordinators, research scientists, research assistants, and data managers associated with RCTs participated. The consensus development workshops were based on the consensus development conference method used to develop best practice for treatment of medical conditions. Workshops commenced with a presentation of the evidence for incentives, communication, questionnaire format, behavioral, case management, and methodological retention strategies identified by a Cochrane review and associated qualitative study. Three simultaneous group discussions followed focused on (1) how convinced the workshop participants were by the evidence for retention strategies, (2) barriers to the use of effective retention strategies, (3) types of RCT follow-up that retention strategies could be used for, and (4) strategies for future research. Summaries of each group discussion were fed back to the workshop. Coded content for both workshops was compared for agreement and disagreement. Agreed consensus on best practice guidance for retention was identified.

Results

Workshop participants agreed best practice guidance for the use of small financial incentives to improve response to postal questionnaires in RCTs. Use of second-class post was thought to be adequate for postal communication with RCT participants. The most relevant validated questionnaire was considered best practice for collecting RCT data. Barriers identified for the use of effective retention strategies were: the small improvements seen in questionnaire response for the addition of monetary incentives, and perceptions among trialists that some communication strategies are outdated. Furthermore, there was resistance to change existing retention practices thought to be effective. Face-to-face and electronic follow-up technologies were identified as retention strategies for further research.

Conclusions

We developed best practice guidance for the use of retention strategies in RCTs and identified potential barriers to the use of effective strategies. The extent of agreement on best practice is limited by the variability in the currently available evidence. This guidance will need updating as new retention strategies are developed and evaluated.

Use of a motivational interviewing-informed strategy in group orientations to improve retention and intervention attendance in a randomized controlled trial

High retention and treatment adherence are essential to ensure the quality of evidence from clinical trials. Strategies for improving these have been explored but actual rates in lifestyle intervention trials indicate challenges. This study examined the use of a motivational interviewing-informed strategy during interactive group orientations prior to obtaining informed consent, collecting baseline data and randomization in a healthy dietary pattern intervention trial for asthma control in adults. The themes generated from small group discussions and echoed in large group discussions during the orientation sessions helped potential participants better understand the scientific rationale of the research design and procedures and the practical implications for them to participate in the study. Potential participants reported significantly lower confidence of completing the study after the group orientation. This suggests that the group orientations helped potential participants identify challenges to completing the study, have more realistic expectations about participation and be prepared if enrolled. Both retention (92% of 90 participants at 6 months) and intervention attendance (99% of 46 intervention participants attended 80% of 11 weekly group/individual sessions) were high, suggesting the motivation interviewing-informed group orientation strategy may help improve retention and adherence in clinical trials.

Increasing follow-up questionnaire response rates in a randomized controlled trial of telehealth for depression: three embedded controlled studies

BACKGROUND

Attrition is problematic in trials, and may be exacerbated in longer studies, telehealth trials and participants with depression - three features of The Healthlines Study. Advance notification, including a photograph and using action-oriented email subject lines might increase response rates, but require further investigation. We examined the effectiveness of these interventions in three embedded Healthlines studies.

METHODS

Based in different trial sites, participants with depression were alternately allocated to be pre-called or not ahead of the 8-month follow-up questionnaire (Study 1), randomized to receive a research team photograph or not with their 12-month questionnaire (Study 2), and randomized to receive an action-oriented ('ACTION REQUIRED') or standard ('Questionnaire reminder') 12-month email reminder (Study 3). Participants could complete online or postal questionnaires, and received up to five questionnaire reminders. The primary outcome was completion of the Patient Health Questionnaire (PHQ-9). Secondary outcome measures were the number of reminders and time to questionnaire completion.

RESULTS

Of a total of 609 Healthlines depression participants, 190, 251 and 231 participants were included in Studies 1-3 (intervention: 95, 126 and 115), respectively. Outcome completion was ≥90 % across studies, with no differences between trial arms (Study 1: OR 0.38, 95 % CI 0.07-2.10; Study 2: OR 0.84, 95 % CI 0.26-2.66; Study 3: OR 0.53 95 % CI 0.19-1.49). Pre-called participants were less likely to require a reminder (48.4 % vs 62.1 %, OR 0.41, 95 % CI 0.21-0.78), required fewer reminders (adjusted difference in means -0.67, 95 % CI -1.13 to -0.20), and completed follow-up quicker (median 8 vs 15 days, HR 1.35, 95 % CI 1.00-1.82) than control subjects. There were no significant between-group differences in Studies 2 or 3.

CONCLUSIONS

Eventual response rates in this trial were high, with no further improvement from these interventions. While the photograph and email interventions were ineffective, pre-calling participants reduced time to completion. This strategy might be helpful when the timing of study completion is important. Researchers perceived a substantial benefit from the reduction in reminders with pre-calling, despite no overall decrease in net effort after accounting for pre-notification.

TRIAL REGISTRATION

Current Clinical Trials ISRCTN14172341.