Two controlled trials to increase participant retention in a randomized controlled trial of mobile phone-based smoking cessation support in the United Kingdom.

BACKGROUND: Loss to follow-up of trial participants represents a threat to research validity. To date, interventions designed to increase participants' awareness of benefits to society of completing follow-up, and the impact of a telephone call from a senior female clinician and researcher requesting follow-up have not been evaluated robustly. PURPOSE: Trial 1 aimed to evaluate the effect on trial follow-up of written information regarding the benefits of participation to society. Trial 2 aimed to evaluate the effect on trial follow-up of a telephone call from a senior female clinician and researcher. METHODS: Two single-blind randomized controlled trials were nested within a larger trial, Txt2stop. In Trial 1, participants were allocated using minimization to receive a refrigerator magnet and a text message emphasizing the benefits to society of completing follow-up, or to a control group receiving a simple reminder regarding follow-up. In Trial 2, participants were randomly allocated to receive a telephone call from a senior female clinician and researcher, or to a control group receiving standard Txt2stop follow-up procedures. RESULTS: Trial 1: 33.5% (327 of 976) of the intervention group and 33.8% (329 of 974) of the control group returned the questionnaire within 26 weeks of randomization, risk ratio (RR) 0.99; 95% confidence interval (CI) 0.88-1.12. In all, 83.3% (813 of 976) of the intervention group and 82.2% (801 of/974) of the control group sent back the questionnaire within 30 weeks of randomization, RR 1.01; 95% CI 0.97, 1.05. Trial 2: 31% (20 of 65) of the intervention group and 32% (20 of 62) of the control group completed trial follow-up, RR 0.93; 95%CI 0.44, 1.98. CONCLUSIONS: In presence of other methods to increase follow-up neither experimental method (refrigerator magnet and text message emphasizing participation's benefits to society nor a telephone call from study's principal investigator) increased participant follow-up in the Txt2stop trial.

Three controlled trials of interventions to increase recruitment to a randomized controlled trial of mobile phone based smoking cessation support.

BACKGROUND: Recruitment is a major challenge for trials but there is little evidence regarding interventions to increase trial recruitment. We report three controlled trials of interventions to increase recruitment to the Txt2stop trial. PURPOSE: To evaluate: Trial 1. The impact on registrations of a text message regarding an online registration facility; Trial 2. The impact on randomizations of sending pound5 with a covering letter to those eligible to join the trial; Trial 3. The impact on randomizations of text messages containing quotes from existing participants. METHODS: Single blind controlled trials with allocation concealment. INTERVENTIONS: Trial 1: A text message regarding our new online registration facility; Trial 2: A letter with pound5 enclosed; Trial 3: A series of four text messages containing quotes from participants. The control group in each trial received standard Txt2stop procedures. RESULTS: Trial 1: 3.6% (17/470) of the intervention group and 1.1% (5/467) of the control group registered for the trial, risk difference 2.5% (95% CI 0.6-4.5). 0% (0/ 470) of the intervention group and 0.2% (1/467) of the control group registered successfully online, risk difference -0.2 (95% CI -0.6-0.2); Trial 2: 4.5% (11/246) of the intervention group and 0.4% (1/245) of the control group were randomized into the Txt2stop trial, risk difference 4.0% (95% CI 1.4-6.7); Trial 3: 3.5% (14/405) of the intervention group and 0% (0/406) of the control group were randomized into the Txt2stop trial, risk difference 3.5 (95% CI 1.7-5.2). LIMITATIONS: There were no baseline data available for trial 1. Allocation of participant IDs in trials 2 and 3 were systematic. CONCLUSION: Sending a text message about an online registration facility increased registrations to Txt2stop, but did not increase online registrations. Sending a pound5 reimbursement for participants' time and sending text messages containing quotes from existing participants increased randomizations into the Txt2stop trial. Clinical Trials 2010; 7: 265-273. http://ctj.sagepub.com.

Using marketing theory to inform strategies for recruitment: a recruitment optimisation model and the txt2stop experience.

BACKGROUND: Recruitment is a major challenge for many trials; just over half reach their targets and almost a third resort to grant extensions. The economic and societal implications of this shortcoming are significant. Yet, we have a limited understanding of the processes that increase the probability that recruitment targets will be achieved. Accordingly, there is an urgent need to bring analytical rigour to the task of improving recruitment, thereby increasing the likelihood that trials reach their recruitment targets. This paper presents a conceptual framework that can be used to improve recruitment to clinical trials. METHODS: Using a case-study approach, we reviewed the range of initiatives that had been undertaken to improve recruitment in the txt2stop trial using qualitative (semi-structured interviews with the principal investigator) and quantitative (recruitment) data analysis. Later, the txt2stop recruitment practices were compared to a previous model of marketing a trial and to key constructs in social marketing theory. RESULTS: Post hoc, we developed a recruitment optimisation model to serve as a conceptual framework to improve recruitment to clinical trials. A core premise of the model is that improving recruitment needs to be an iterative, learning process. The model describes three essential activities: i) recruitment phase monitoring, ii) marketing research, and iii) the evaluation of current performance. We describe the initiatives undertaken by the txt2stop trial and the results achieved, as an example of the use of the model. CONCLUSIONS: Further research should explore the impact of adopting the recruitment optimisation model when applied to other trials.

Do messages of scarcity increase trial recruitment?

INTRODUCTION: Psychological theory suggests that participants may be more likely to volunteer to join a clinical trial if they perceive places in the trial are a scarce commodity. MATERIAL AND METHODS: We conducted a single blind, randomized controlled trial to test recruitment strategies within the larger txt2stop smoking cessation trial. 1862 people who were eligible for the txt2stop trial but had not yet consented to join were randomized to receive either A) a reminder about the txt2stop trial plus a message that there were only 300 places left, or B) a reminder about the trial only. The outcome was the participant's consent to join the txt2stop trial 3days after messages were sent. RESULTS: Of 895 participants randomized to the intervention group, 90 (10.1%) had consented to join the txt2stop trial. Of the 967 participants randomized to the control group, 67 (6.9%) had consented to join the txt2stop trial (OR=1.50, 95% CI 1.07-2.12). DISCUSSION: Scarcity messages were an effective way to increase recruitment into the txt2stop trial and could be relevant to other trials. CONCLUSIONS: Communicating scarcity is an effective way to increase trial recruitment.