Original Article
Telephone call reminders did not increase screening uptake more than SMS reminders: a recruitment study within a trial

https://doi.org/10.1016/j.jclinepi.2019.04.009Get rights and content

Abstract

Objectives

The aim of the study was to compare the response rates and costs of phone call vs. short message service (SMS) screening reminders to prospective randomized controlled trial (RCT) participants.

Study Design and Setting

This study was a randomized evaluation within a large Australian diabetes prevention RCT. Participants were men aged 50–74 years, overweight or obese, without a previous type 2 diabetes diagnosis. Those eligible on a prescreening questionnaire who did not attend a further screening assessment within 4 weeks were randomized to receive an SMS or phone call reminder (N = 709). The primary outcome was attendance for further screening assessment within 8 weeks of prescreening.

Results

Attendance was 18% (62/354) in the SMS reminder group, and 23% (80/355) in the phone reminder group, with no statistically significant difference in response according to reminder type (relative risk = 1.29, 95% confidence interval [CI]: 0.96–1.73, P = 0.09). The lower confidence limits for response to SMS (95% CI: 14–22%) and phone reminders (95% CI: 18–27%) did not include the 8-week attendance rate before this evaluation, 12%. Phone reminders cost substantially more than SMS reminders (AU$6.21 vs. AU$0.53 per reminder).

Conclusion

SMS reminders were as adequate a method as phone reminders to boost RCT screening uptake and were considerably more affordable.

Introduction

Recruitment of participants to randomized controlled trials (RCTs) is challenging, and an estimated 50% of trials fail to reach their recruitment targets [1], [2]. Disease prevention RCTs face additional recruitment challenges compared with those for disease treatment, reporting higher attrition of volunteers at each stage of recruitment [3]. Several explanations for this observation have been proposed. First, disease prevention RCTs commonly seek to enroll healthy individuals who may perceive their risk of disease to be low, reducing their motivation to participate in clinical research [4], [5]. Second, participants in disease prevention RCTs must usually be identified directly from the general public rather than through clinician referral [6], [7]. Lack of involvement in recruitment by a potential volunteer's personal clinician may leave an individual unsure about the suitability of the trial for them [8] or misunderstanding the trial processes [4], reducing interest in participation.

In RCTs where attrition during early recruitment and initial screening phases is important, interventions to address participant uncertainty and low motivation may boost recruitment, saving time and money. In studies evaluating the use of participant reminders [9], [10], [11], phone calls increased RCT enrollment among individuals who failed to respond to an initial mailed invitation compared with no reminder [10] and to a mailed reminder [11]. Also, a series of four short message service (SMS) reminders increased enrollment (compared with no reminder) among participants who did not respond after initial screening [12]. Elsewhere, health services research shows strong evidence that SMS reminders are as effective as phone call reminders for improving attendance at clinic appointments [13], [14], [15]. However, to our knowledge, no randomized evaluation has been published comparing SMS and phone reminders to improve recruitment to RCTs [16]. Unlike an SMS, a phone call reminder provides the opportunity to build rapport and to clarify specific uncertainties, arguably more important for participants interested in joining a disease prevention RCT than for patients due to attend a prebooked clinic appointment for disease management. By contrast, SMS reminders have the advantage of being cheaper [13], less intrusive, and providing written information that participants can refer to later.

Men are underrepresented in disease prevention and health promotion RCTs [7], [17] despite experiencing higher rates of avoidable mortality than women [18]. In the past, men have been mischaracterized as disinterested in health promotion and disease prevention, but there is growing recognition that men care about their health and engage with health services if they are tailored to their needs [19], [20]. Men may prefer to monitor their own health needs and gather information independently before making the decision to engage with professional health services [21]. We hypothesized that SMS reminders may address this preference for independent decision-making in our male participants.

This study within a trial (SWAT) aimed to compare, in randomized fashion, the efficacy and cost-effectiveness of phone call and SMS reminders in improving attendance for screening assessments for a large multicenter diabetes prevention RCT (registered as SWAT 88 on the SWAT repository).

Section snippets

Setting

This reminder study was conducted in the context of the Testosterone for Diabetes Mellitus (T4DM) trial. The design of the T4DM study is published elsewhere [22], but briefly, T4DM is a Phase III, multicenter, double-blind, placebo-controlled trial of testosterone for the prevention of diabetes or reversal of newly diagnosed diabetes (trial registration ACTRN12612000287831). The trial is run through six Australian hospital-based centers and is coordinated by a central university-based

Results

The T4DM study was open to recruitment from January 2013 to February 2017. In that time, 19,022 participants were screened, and 1,007 were randomized. The reminder study opened to recruitment in June 2016 and closed in October 2016, the week that the calculated sample size was attained. During that period, 2,315 participants were screened to the main study, and 709 of them were eligible for the reminder study (having neither attended nor declined laboratory screening within 4 weeks of

Summary of findings

In this randomized evaluation of screening reminders, there was no statistically significant difference in response to phone call and SMS reminders (RR = 1.29, 95% CI: 0.96–1.73, P = 0.09). However, the overall attendance rate in those who received a phone or SMS reminder was 20% at 8 weeks, compared with the previously observed attendance rate of 12% in the main study. As in similar studies [13], [14], we found that phone reminders were substantially more expensive to perform than SMS

Conclusion

Compared with SMS reminders, phone call reminders were more costly and did not significantly increase the screening uptake rate of nonresponders in this large multicenter RCT. There was some suggestion that phone call reminders were more effective than SMS reminders in men ≥aged 65 years. SMS reminders were substantially cheaper and quicker to perform than phone call reminders, making them a promising approach for boosting recruitment in RCTs with limited budgets.

Acknowledgments

The authors thank the coordinating center team: Caitlin Van Holst Pellekaan and Sandra Healey (NHMRC Clinical Trials Center); the T4DM study nurses: Glenda Fraser (ANZAC Research Institute and Concord Hospital), Jenny Healy (Austin Hospital), Helen Daniels and Chyn Soh (Fremantle Hospital and Fiona Stanley Hospital), Jody Sawyer (Princess Alexandra Hospital), Rosemary Cox and Fiona Cossey (The Queen Elizabeth Hospital), Lee Mahoney (The Keogh Institute for Medical Research); Sherilyn Goldstone

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  • Cited by (0)

    Funding: This work was supported by a National Health and Medical Research Council of Australia (NHMRC), Australia Project Grant 1030123, Bayer, Lilly, University of Adelaide, and NHMRC Clinical Trials Centre, University of Sydney.

    Conflicts of interest: G.W. has received research funding from Bayer, Lilly, Lawley Pharmaceuticals, and Weight Watchers and speaker honoraria from Bayer, Lilly, and Besins Health Care. C.A. has received honoraria from Besins Health Care and is an advisory board member for Ferring. M.G. has received research funding from Bayer, Novartis, Weight Watchers, and Lilly and speaker's honoraria from Besins Healthcare and Otsuka. D.J.H. has received institutional grants for investigator-initiated studies of testosterone pharmacology (Lawley, Besins Healthcare) but no personal income and has provided expert testimony to antidoping and professional standards tribunals and testosterone litigation. B.B.Y. has received speaker honoraria and conference support from Bayer, Lilly, and Besins Healthcare, research support from Bayer, Lilly, and Lawley Pharmaceuticals, and has been a member of advisory committees for Lilly and Besins. A.Ke. has received honoraria from Amgen, Novartis, Mylan, Pfizer, Sanofi, and Bayer. K.B., A.C., M.D., W.H., V.G., W.I., A.J., R.M., K.R., B.S., and A.Ki. declare no relevant conflicts of interest.

    Authors’ contributions: G.W., C.A., A.C., M.D., V.G., M.G., W.H., D.J.H., W.I., A.J., A.Ke., R.M., B.S., and B.Y.Y. conceived the Testosterone for Diabetes Mellitus study. K.B., G.W., W.H., A.Ke., and A.Ki. designed the evaluation presented in this article. K.B. and K.P.R. carried out the evaluation and collected the data. K.B., K.P.R., and A.Ki. performed the statistical analyses. K.B. wrote the first draft of the article. All authors revised and approved the article.

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