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From the CTN Special Issue of American Journal of Drug and Alcohol Abuse: Read the other articles here.




Relation of Study Design to Recruitment and Retention in CTN Trials.

American Journal of Drug and Alcohol Abuse 2011;37(5):426-433. [doi: 10.3109/00952990.2011.596972]

Paul G. Wakim, PhD, Carmen L. Rosa, MS, Prasad Kothari, MS, Mary Ellen Michel, PhD (all from the Center for the Clinical Trials Network, NIDA).

Recruitment and retention in randomized clinical trials are difficult in general and particularly so in trials of substance abuse treatments. Understanding trial design characteristics that could affect recruitment and retention rates would help in the design of future trials. This study aimed to test whether any of the following factors are associated with recruitment or retention: type of intervention, type of therapy, duration of treatment, total duration of trial, number of treatment sessions, number of follow-up visits, number of primary assessments, timing of primary assessments, number of case report form (CRF) pages at baseline, and number of CRF pages for the entire trial. Recruitment and retention data from 24 Clinical Trials Network (CTN) trials conducted and completed between 2001 and 2010 were analyzed using single-factor analysis of variance and single-predictor regression methods to test their association with trial design characteristics. Almost all of the analyses performed did not show statistically significant patterns between recruitment and retention rates and the trial design characteristics considered.

Conclusions: In CTN trials, the relationship between assessment burden on participants and length of trial, on the one hand, and recruitment and retention, on the other, is not as strong and direct as expected. Other factors must impinge on the conduct of the trial to influence trial participation. Researchers may deem it slightly more justifiable to permit inclusion of some of the design features that previously were assumed to have a strong, negative influence on recruitment and retention, and should consider other strategies that may have a stronger, more direct effect on trial participation. That said, although critical, recruiment and retention should be kept in perspective; they do not in and of themselves make a clinical trial "successful." The ultimate goal is to design clinical trials that produce clinically meaningful findings; a clinical trial with great recruitment and retention, but fundamentally flawed design, is unlikely to provide valid or useful results. (Article (Peer-Reviewed), PDF, English, 2011)

Keywords: CTN protocol development | CTN platform/ancillary study | Recruitment | Research design | Retention - Research | American Journal of Drug and Alcohol Abuse (journal)

Document No: 744, PMID: 21854286, PMC3174089.

Submitted by CTN Dissemination Librarians, 8/23/2011.


Kothari, Prasad
Michel, Mary Ellen mail
Rosa, Carmen L. mail
Wakim, Paul G. mail

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Supported by a grant from the National Institute on Drug Abuse to the University of Washington Alcohol and Drug Abuse Institute.
The materials on this site have neither been created nor reviewed by NIDA.
Updated 9/2011 --
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