Why is recruitment to trials difficult? An investigation into recruitment difficulties in an RCT of supported employment in patients with severe mental illness.

Background: Under-recruitment to randomised controlled trials (RCTs) is often problematic and there may be particular difficulties in recruiting patients with severe mental illness.

Aim: To evaluate reasons for under-recruitment in an RCT of patients with severe mental illness

Methods: Qualitative study during the recruitment phase of an RCT of supported employment. Trial staff and recruiting clinicians were interviewed. Data were analyzed thematically using constant comparative techniques.

Results: Recruitment rates were low. Five main reasons for recruitment difficulties were found. These included: (i) misconceptions about trials, (ii) lack of equipoise, (iii) misunderstanding of the trial arms, (iv) variable interpretations of eligibility criteria, (v) paternalism.

Conclusion: Reasons for recruitment difficulties in trials involving patients with severe mental illness include issues that occur in trials in general, but others are more specific to these patients. Clinician and patient involvement in the study design may improve recruitment in future similar trials.