Telephone reminders are effective in recruiting nonresponding patients to randomized controlled trials. Recruiting patients to medical research: double blind randomised trial of "opt-in" versus "opt-out" strategies. Impact of privacy legislation on the number and characteristics of people who are recruited for research: a randomised controlled trial. Do messages of scarcity increase trial recruitment? Optimising recruitment into a study of physical activity in older people: a randomised controlled trial of different approaches. A randomised trial of the effects of an additional communication strategy on recruitment into a large-scale, multi-centre trial. A randomized trial of the impact of telephone and recorded delivery reminders on the response rate to research questionnaires. Three controlled trials of interventions to increase recruitment to a randomized controlled trial of mobile phone based smoking cessation support. Successful recruitment of minorities into clinical trials: The Kick It at Swope project.
Studies investigating means of recruiting participants to randomized controlled trials (RCTs) are sparse. We investigated the effects of telephone reminders as a recruitment strategy.
                Sick-listed employees received a written invitation to participate in a study comparing standard treatments with a solution-focused follow-up and were randomly allocated to an intervention or control group (n=703). Those who did not respond within 2 weeks received either 'no reminder' (n=242) or 'attempted telephone reminder' (n=256). Outcome was enrollment to the RCT.
                An intention to recruit analysis revealed no significant differences between the groups (P=.229). An intention to phone analysis among nonresponders revealed significant differences between 'no reminder' (recruited 4.5%) and 'attempted telephone reminder' (recruited 12.1%) (P=.003, odds ratio 2.89, 95% confidence interval [CI] 1.42-5.90). An analysis of numbers needed to phone showed that to recruit one more person in this group of nonresponders, we needed to phone 13 persons (95% CI=8-33).
                Systematic use of telephone calls can increase the recruitment rate among nonresponders in RCTs. To evaluate the effect of opt-in compared with opt-out recruitment strategies on response rate and selection bias.
                Double blind randomised controlled trial.
                Two general practices in England.
                510 patients with angina.
                Patients were randomly allocated to an opt-in (asked to actively signal willingness to participate in research) or opt-out (contacted repeatedly unless they signalled unwillingness to participate) approach for recruitment to an observational prognostic study of patients with angina.
                Recruitment rate and clinical characteristics of patients.
                The recruitment rate, defined by clinic attendance, was 38% (96/252) in the opt-in arm and 50% (128/258) in the opt-out arm (P = 0.014). Once an appointment had been made, non-attendance at the clinic was similar (20% opt-in arm v 17% opt-out arm; P = 0.86). Patients in the opt-in arm had fewer risk factors (44% v 60%; P = 0.053), less treatment for angina (69% v 82%; P = 0.010), and less functional impairment (9% v 20%; P = 0.023) than patients in the opt-out arm.
                The opt-in approach to participant recruitment, increasingly required by ethics committees, resulted in lower response rates and a biased sample. We propose that the opt-out approach should be the default recruitment strategy for studies with low risk to participants. Privacy laws have recently created restrictions on how researchers can approach study participants. Method: In a randomised trial of 152 patients, 50-74 years old, in a family practice, 60 were randomly selected to opt-out and 92 to opt-in methods. Patients were sent an introductory letter by their doctor in two phases, opt-out before and opt-in after introduction of the new Privacy Legislation in December 2001. Opt-out patients were contacted by researchers. Opt-in patients were contacted if patients responded by email, free telephone number or a reply-paid card.
                Opt-in recruited fewer patients (47%; 43/92) after invitation compared with opt-out (67%; 40/60); (-20%; [-4% to -36%]). No proportional difference in recruitment was found between opt-in and opt-out groups varied by age, sex or socioeconomic status. The opt-in group had significantly more people in active decision-making roles (+30%; [10% to 50%]; p = 0.003). Non-significant trends were observed towards opt-in being less likely to include people with lower education (-11.8%; [-30% to 6.4%]; p = 0.13) and people who were not screened (-19.1%; [-40.1% to 1.9%]; p = 0.08). Opt-in was more likely to recruit people with a family history of colorectal cancer (+12.7%; [-2.8%, 28.2%]; p = 0.12).
                The number of participants required to be approached was markedly increased in opt-in recruitment. Existing participants (eg, screening attendees) with a vested interest such as increased risk, and those preferring an active role in health decision making and with less education were likely to be recruited in opt-in. Research costs and generalisability are affected by implementing privacy legislation. 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.
                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.
                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).
                Scarcity messages were an effective way to increase recruitment into the txt2stop trial and could be relevant to other trials.
                Communicating scarcity is an effective way to increase trial recruitment.
                Copyright © 2010 Elsevier Inc. All rights reserved. physical activity studies in older people often have poor recruitment. Including a questionnaire with the invitation would provide information about non-participants and selection bias, but could reduce recruitment. Telephone contact might encourage participation.
                to test the effects of different strategies for recruitment into a study of physical activity in older people.
                factorial randomised controlled trial. Randomisation by household into four groups: telephone contact plus questionnaire, telephone contact only, questionnaire only, neither.
                primary care, Oxfordshire, United Kingdom.
                560 patients > or = 65 years randomly selected after exclusions.
                questionnaire to assess health, functional ability and physical activity. Telephone contact by the research nurse a week after sending study information.
                recruitment into physical activity study.
                telephone contact increased recruitment: contact 47.9% (134/280), no contact 37.9% (106/280), difference (adjusted for the clustering effect of household) 10.0% (95% CI 0.2-19.8). Questionnaire inclusion did not significantly reduce recruitment: no questionnaire 44.3% (124/280) questionnaire 41.4% (116/280) difference -2.9% (95% CI -12.7-7.0).
                telephone contact significantly increased recruitment and should be considered in studies where recruitment may be low. While inclusion of a questionnaire provided valuable information on non-participants and did not significantly reduce recruitment, an adverse recruitment effect could not be excluded. Timely participant recruitment remains a significant challenge for most clinical trials. We evaluated the effects on participant recruitment of communication between the central trial coordinators and the clinical sites in the setting of a large international multi-centre clinical trial. The effects of communication were determined in a single-blind randomised controlled trial involving 167 clinical sites in 19 countries. Clinical sites were randomised to either additional or usual communication strategies - the additional communication group received a communication package based on additional, individually-tailored feedback about recruitment, in addition to the usual correspondence from the central trial coordinators that was provided to the control group. The two study outcomes were the median time to half randomisation target and the median total number of participants randomised per clinical site. Eighty-five clinical centres were randomised to receive additional communication and 82 to receive usual communication. At the conclusion of recruitment, there was no significant difference in the median number of participants randomised per centre between the additional and usual groups (37.5 vs. 37.0, p=0.68). The median time to half randomisation target was lower in the additional communication group compared to the usual group, however this difference did not achieve conventional levels of statistical significance (4.4 months vs. 5.8 months, p=0.08). The findings suggest that the additional communication strategy may be of some incremental benefit in helping sites achieve recruitment targets sooner. A range of factors have been shown to affect the response rate to mailed questionnaires, but particular strategies to improve patients' response in trials conducted in general practice require further study.
                Non-responders in a larger trial were randomized to receive a telephone or recorded delivery reminder on the third contact. The cost of administration of each method was estimated.
                Significantly more patients returned completed questionnaires when sent questionnaires by recorded delivery, although the cost per patient contacted was nearly three times more than for contact by telephone.
                Our study indicates that sending reminders by recorded delivery, although more expensive, is more effective than telephone reminders for recruiting patients to a study in general practice using research questionnaires. 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.
                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.
                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.
                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).
                There were no baseline data available for trial 1. Allocation of participant IDs in trials 2 and 3 were systematic.
                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. Ethnic minorities are often underrepresented in clinical trials, and their recruitment can challenge researchers. Developing and communicating effective and efficient recruitment strategies may help researchers enroll more minorities into research studies. Kick It at Swope was a double-blind, randomized trial that evaluated bupropion for smoking cessation among 600 adult African Americans who smoked 10 or more cigarettes a day. Proactive recruitment strategies (in-person appeals by study staff and health care providers) and reactive recruitment strategies (disseminating information that asked people to call a study hotline) were implemented sequentially in an additive fashion over 16 months. Resulting patterns of recruitment are described and the two phases are compared based on their relative effectiveness, efficiency, and cost. More enrollees were recruited in the reactive phase (n=534) than in the proactive phase (n=66). Those recruited in the reactive phase were more likely to be eligible (OR=4.8) and more likely to be enrolled (OR=4.2) than those recruited in the proactive phase. Participants recruited in the reactive phase reported significantly higher levels of education and income, better health, and significantly lower indicators of depression and life hassles, compared with those recruited in the proactive phase. The reactive recruitment phase was less expensive than the proactive recruitment phase (22 US Dollars/enrollee vs. 159 US Dollars/enrollee). Reactive recruitment strategies added to multiple proactive clinic-based recruitment strategies were more effective, more efficient, and less costly than proactive recruitment alone. Close monitoring combined with the use of multiple recruitment methods and flexible recruitment plans can lead to successful, efficient, and low-cost recruitment of minorities into clinical trials.
There are promising strategies for increasing recruitment to trials: telephone reminders; requiring potential participants to opt-out of being contacted by the trial team regarding taking part in a trial, rather than them having to opt-in, and open designs. Some strategies (e.g. open trial designs) need to be considered carefully before use because they also have disadvantages. For example, opt-out procedures are controversial and open designs are by definition unblinded.