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Randomized Controlled Trial
. 2015 Aug;68(8):877-87.
doi: 10.1016/j.jclinepi.2015.03.014. Epub 2015 Mar 31.

Professionally designed information materials and telephone reminders improved consent response rates: evidence from an RCT nested within a cohort study

Andy Boyd  1 , Kate Tilling  2 , Rosie Cornish  2 , Amy Davies  2 , Kerry Humphries  2 , John Macleod  2
Affiliations
Randomized Controlled Trial

Professionally designed information materials and telephone reminders improved consent response rates: evidence from an RCT nested within a cohort study

Andy Boyd et al. J Clin Epidemiol. 2015 Aug.

Abstract

Objectives: To investigate whether different study-to-participant communication methods increase response, increase response from hard-to-engage individuals, and influence participants' consent decisions.

Study design and setting: A randomized controlled trial within the Avon Longitudinal Study of Parents and Children. Cohort members were invited to re-enroll at age 18 and consent to linkage to their health and administrative records. Participants were randomized to receive one of eight combinations of three interventions: a prior-notification postcard or no contact, a standard or professionally designed consent pack, and a phone or postal reminder. The primary outcome was return of the consent form ("response"), with consent decision being the secondary outcome.

Results: Of 1,950 participants, 806 (41%) responded. Response rates were 2.7% higher (95% confidence interval: -0.06, 5.5%; P = 0.06) among those receiving designed packs than among those receiving standard packs and 6.4% higher (2.3, 10.6%; P = 0.002) among those receiving phone reminders (compared with postal reminders). The prior-notification postcard did not influence response rates [difference = 0% (-2.8, 2.8%; P = 1.0)], and we found no evidence that the communication method influenced consent decision.

Conclusion: This trial provides evidence that communication material design can influence response rates and that phone reminders have superior cost/benefit returns over designed materials. Experimental evaluation of communications strategies and dissemination of findings may benefit cohort studies.

Keywords: ALSPAC; Cohort study; Randomized controlled trial; Record linkage; Recruitment; Retention.

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Figures

Fig. 1
Fig. 1
RCT sample selection and allocation to intervention groups. RCT, randomized controlled trial; ALSPAC, Avon Longitudinal Study of Parents and Children.
Fig. 2
Fig. 2
Summary of the PEARL RCT interventions. PEARL, Project to Enhance ALSPAC through Record Linkage; RCT, randomized controlled trial.
Fig. 3
Fig. 3
Prior-notification postcard and information pack intervention designs.
Fig. 4
Fig. 4
Subgroup analysis: differences in response for the reminder intervention by sociodemographic characteristics. CI, confidence interval; RD, risk difference.
See this image and copyright information in PMC

References

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