A randomized, embedded trial of pre‐notification of trial participation did not increase recruitment rates to a falls prevention trial

Abstract

Objectives To design and evaluate the effectiveness of a pre-notification leaflet about research to increase recruitment to a randomized controlled trial (RCT). Methods A methodological, two-arm, RCT was conducted, embedded within an existing cohort RCT (REFORM). Participants were randomized for the embedded trial, using a 1:2 ratio (intervention : control) before being randomized for REFORM. Controls received a trial recruitment pack. The intervention group received an additional pre-notification leaflet 2-3 weeks before the recruitment pack. Primary and secondary analyses were conducted using relative risk, the Cox proportional hazards model and incremental cost-effectiveness ratios.Results Of the 1436 intervention group participants, 73 (5.1%) were randomized into the REFORM trial compared with 126 (4.4%) of the 2878 control group participants. The associated relative risk (1.16) was not statistically significant [95% confidence interval (CI) 0.88-1.56]. Return rate was not significantly increased (relative risk 1.10, 95% CI 0.92-1.28) nor time to return decreased (hazard ratio: 1.11, 95% CI 0.93-1.33). Incremental cost-effectiveness ratios indicated the intervention may be cost-effective if the true estimate of effect was close to the upper bound of the associated 95% CI. Conclusion Pre-notification for potential trial participants demonstrated a small difference to randomization (0.7% difference) and return rates (1.1% difference) in favour of the intervention. Results should however be interpreted with caution as CIs for these estimates cross the point of no effect. Nevertheless, this research enhances existing evidence for pre-notification to increase recruitment rates, with further development and assessment of this potentially cost-effective intervention being recommended.

Do recruitment SWAT interventions have an impact on participant retention in randomised controlled trials? A systematic review

“…[22][23][24][25][26][27] Most trials (n = 6, 60%) used postal follow-up (patient self-completed diaries/calendars or questionnaires), with the remaining studies using follow-up in a clinic (n = 3, 30%) or telephone followup (n = 1, 10%). Four SWATs (40%) used unequal randomisation, 19,21,23,27 with the majority (n = 3; 75%) favouring the SWAT control arm. 19,21,23 In line with the Online Resource for Recruitment research in Clinical Trials categorisation, and as detailed in Table 1, the majority of SWATs focussed on the information given to participants (n = 6, 60%), [22][23][24][25][26][27] including modifications to patient information sheets (n = 2), modifications to invitation letters (n = 2), modifications to both (n = 1), and provision of a research information leaflet (n = 1).…”

“…Overall, the majority of SWATs (n = 9) were assessed as having some concerns (n = 6) or a high risk of bias (n = 3). [18][19][20][22][23][24][25][26][27] For all SWATs missing outcome data and selection of reported results were well reported. The reasons for some concerns were largely due to limited reporting of the randomisation process or outcome assessment or deviations from the intended intervention.…”

A systematic review of economic evaluations alongside studies within a trial (SWATs) for improving recruitment and retention in randomised controlled trials

“…As there was an uncertainty regarding which data the reviewers from the retention review had accessed, the papers' risk of bias was re-assessed. For recruitment strategies, four included studies (four SWATs) were retrieved from the electronic databases, 22,[25][26][27] one study (one SWAT) was retrieved from manual searching, 28 four studies (10 SWATs) were already included in the recruitment review, 2 and one study (one SWAT) was already included in the retention review. 20 Most SWATs had individually randomised designs; however, two studies (two SWATs) were quasi-randomised, 29,30 a n dt w os t u d i e s( t w oS W A T s )w e r ec l u s t e rr a n d o m i s e d .…”

“…One included study affected the quality appraisal detrimentally, as a full text was unavailable. 26 Recruitment strategies Financial incentives. The ICER of a financial incentive, against no financial incentive, was estimated from two studies (six SWATs).…”

“…The cost-effectiveness of this strategy was estimated according to a single SWAT. 26 With an odds ratio of 1.17 (95% CI: 0.87, 1.57) and an incremental cost of US$2.25, it costs US$25.97 (95% CI: from US$9.00 to N/A) to recruit an additional patient (see Table S3 in Supplemental Material 3 for more details). Given the sample size of the included study 26 , and its low Cochrane risk of bias, the GRADE certainty of evidence is moderate due to imprecision.…”