The ‘Retention in Randomised Control Trials (RRCT)’ Project

Abstract

The Retention in Randomised Control Trials (RRCT) project assessed whether a high retention rate could be achieved in a longitudinal Randomised Control Trial (RCT) - The North-East Cot (NECOT) trial - by implementing various interventions: a relationship based intervention, a combination of interventions (relationship and prepaid incentive), a prepaid incentive intervention and a free sample/prize intervention. The RRCT project used a subset of participants (n=450) from the NECOT trial who were allocated consecutively to one of six groups (two control groups and four intervention groups).

None of the interventions tested had a significant impact on reducing attrition above the normal protocol of the NECOT trial. The relationship based intervention had significantly higher attrition, thus a negative effect, compared to control group 1 (χ2 =7.860, df =1 and p =0.005), control group 2 (χ2 =6.182, df =1 and p =0.013) and the control groups combined (χ2 =9.587, df =1 and p =0.002).

Women who were aged below 25, living without a partner/husband, up to university educated or with a household income up to £20,000 were significantly more likely to drop out of the NECOT trial. Also, women aged below 25, living without a partner/husband, of ‘other’ ethnicity or with a household income up to £20,000 responded best to the prepaid intervention.

The RRCT project provides an anthropological approach to attrition and retention thus contributing to the literature on this subject. Both social and biological anthropological perspectives can be applied to reasons for retention and attrition, for instance Prisoner’s Dilemma, Tit-For-Tat strategy, reciprocal altruism, moral motivation, reciprocity and building social obligations.