Participant recruitment and retention in longitudinal preconception randomized trials: lessons learnt from the Calcium And Pre-eclampsia (CAP) trial

Trials. 2017 Oct 26;18(1):500. doi: 10.1186/s13063-017-2220-0.

Abstract

Background: The preconception period has the potential to influence pregnancy outcomes and randomized controlled trials (RCTs) are needed to evaluate a variety of potentially beneficial preconception interventions. However, RCTs commencing before pregnancy have significant participant recruitment and retention challenges. The Calcium And Pre-eclampsia trial (CAP trial) is a World Health Organization multi-country RCT of calcium supplementation commenced before pregnancy to prevent recurrent pre-eclampsia in which non-pregnant participants are recruited and followed up until childbirth. This sub-study explores recruitment methods and preconception retention of participants of the CAP trial to inform future trials.

Methods: Recruiters at the study sites in Argentina, South Africa and Zimbabwe completed post-recruitment phase questionnaires on recruitment methods used. Qualitative data from these questionnaires and quantitative data on pre-pregnancy trial visit attendance and pregnancy rates up to September 2016 are reported in this paper. RStudio (Version 0.99.903 https://www.rstudio.org ) statistical software was used for summary statistics.

Results: Between July 2011 and 8 September 2016, 1354 women with previous pre-eclampsia were recruited. Recruitment took 2 years longer than expected and was facilitated mainly through medical record/register and maternity ward/clinic-based strategies. Recruiters highlighted difficulties associated with inadequate medical records, redundant patient contact details, and follow-up of temporarily ineligible women as some of the challenges faced. Whilst the attendance rates at pre-pregnancy visits were high (78% or more), visits often occurred later than scheduled. Forty-five percent of participants became pregnant (614/1354), 33.5% (454/1354) within 1 year of randomization.

Conclusions: In preconception trials, both retrospective and prospective methods are useful for recruiting eligible women with certain conditions. However, these are time-consuming in low-resource settings with suboptimal medical records and other challenges. Trial planners should ensure that trial budgets cover sufficient on-site researchers with pre-trial training, and should consider using mobile phone and web-based electronic tools to optimize recruitment and retention. This should lead to greater efficiency and shorter trial durations.

Trial registration: Pan-African Clinical Trials Registry, Registration Number: PACTR201105000267371 . The trial was registered on 6 December 2016.

Keywords: Calcium; Pre-eclampsia; Preconception; Randomized; Recruitment; Retention.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Argentina
  • Calcium Carbonate / adverse effects
  • Calcium Carbonate / therapeutic use*
  • Dietary Supplements* / adverse effects
  • Double-Blind Method
  • Female
  • Humans
  • Patient Dropouts
  • Patient Selection*
  • Pre-Eclampsia / diagnosis
  • Pre-Eclampsia / physiopathology
  • Pre-Eclampsia / prevention & control*
  • Preconception Care / methods*
  • Pregnancy
  • Recurrence
  • Risk Factors
  • Sample Size
  • South Africa
  • Surveys and Questionnaires
  • Time Factors
  • Treatment Outcome
  • Zimbabwe

Substances

  • Calcium Carbonate