Recruitment into a guided internet based CBT (iCBT) intervention for depression: lesson learnt from the failure of a prevalence recruitment strategy

Introduction: Internet based Cognitive Behavioural Therapy (iCBT) represents a significant development in the way psychological interventions are delivered. Studies tend to recruit via common media channels leading to criticisms of biased sample sizes and limited generalisability to primary care settings.

Aim: To evaluate the use of a prevalence recruitment strategy within primary care to recruit into an RCT examining a free to use iCBT intervention.

Methods: Fully randomised controlled trial (RCT), utilising a prevalence based recruitment strategy, comparing the iCBT intervention with telephone support provided by NHS Direct Health Advisors with treatment-as-usual (TAU) control.

Results: Recruitment rates were low with only 7 participants recruited over 8 months. Overall only 14% of expected study invitations were sent, with only 1% undertaking the consent and initial screening process.

Discussion: Key differences with successful prevalence recruitment strategies highlight four main issues to consider when recruiting participants from primary care into iCBT studies--lack of equipoise, a need for an assertive approach, coding of depression in GP databases and help seeking behaviour in depression which can all act as potential contributors to failure to recruit. However other non-primary care recruitment methods, such as the use of media channels, which are already shown to be effective in non-primary care settings should be considered if these methods more accurately target the population who would be willing to adopt iCBT more generally.