How Much Is the Lack of Retention Evidence Costing Trial Teams in Ireland and the United Kingdom?
Abstract BackgroundEvidence to support the use of many retention strategies in clinical trials is lacking. Despite this, trial teams still need to have some form of retention strategy in their trials to try and avoid high attrition rates. This study aimed to estimate how much this lack of retention evidence might be costing trials in Ireland and the United Kingdom.Methods We selected the top ten most routinely used retention strategies by Clinical Trial Units in the United Kingdom and made assumptions as to how each of these strategies was most likely to be conducted and the costs involved. We applied our costing model to a hypothetical trial scenario in both Ireland and the United Kingdom as well as to three published trial protocols. We developed the costing model and calculated the costs in Microsoft Excel.Results Retention strategies can be extremely expensive, some of the costliest interventions included “a timeline of participant visits for sites” (with integrated participant reminders) (€1,418.44 - €108,471.99), “routine site visits by CTU staff” (€777.67 - €14,753.48), and “data collection scheduled with routine care” (€900 - €32,503.25). Others such as “telephone reminders for questionnaire response” (€34.58 - €568.62), “inclusion of pre-paid envelopes” (€93.44 - €942.50), and “targeted recruitment of sites/GPs” (€30 - €1,620) were less costly compared to the other interventions. DiscussionThe resources invested in the use of some retention interventions may outweigh known or imagined benefits on retention. Where benefits are imagined, evaluation should be a priority. Conclusion More evaluation of the effectiveness and cost of trial retention strategies is needed to avoid widespread use of strategies that are both expensive and ineffective.