DIALOG+ for service users with chronic depression: a cluster-randomised controlled feasibility trial and qualitative evaluation

Many individuals who experience depression go on to develop chronic forms of this disorder yet research on tailored treatments is lacking. DIALOG +, a technology-assisted and resource-oriented intervention, may be one potential solution. This study aimed to assess the feasibility and acceptability of conducting a definitive cluster randomized controlled trial (cRCT) of DIALOG + for service users with chronic depression. A mixed-methods feasibility study involving a two-arm cRCT and qualitative evaluation was conducted in community-based mental health care services in South-East England. Service users with a clinical diagnosis of chronic depression (≥ 2 years), and their clinicians, were cluster-randomized to either the intervention (DIALOG +) or an active control (Treatment as Usual + completion of the DIALOG scale) group. Participants were assessed at baseline and 6 months post-randomisation by blinded assessors. The DIALOG + arm participants were interviewed about their experiences. The feasibility of recruitment and retention strategies, eligibility criteria, and selected outcome measures including their estimated variability were all assessed. Acceptability of DIALOG + and fidelity evaluation recording methods were also explored. Thirty-six service users and 11 clinicians were cluster-randomised to the intervention arm (n = 25/8) or the active control arm (n = 11/3). 75% of the target service user sample and 92% of the clinician sample were recruited. The service user retention rate was 77.8%. Recruitment was affected by organisational-level difficulties, however, all consented and eligible service users were randomised. Eligibility criteria for the subsequent main trial were modified to ensure adequate inclusiveness. The outcome measures used were feasible except for the clinician-rated ones which required replacement. No formal between-group tests were conducted however the results indicated a trend towards increased subjective quality of life (SQOL) and a decrease in depressive symptoms at 6-months in the DIALOG + arm. Qualitative interviews were conducted with 7 service users and 6 clinicians, with data indicating that DIALOG + is acceptable due to the intervention providing increased clarity and focus, and positively impacting on clinical communication. 85.7% of service users indicated they would want to use DIALOG + again in the future. A definitive cRCT is feasible to conduct with some adjustments to the recruitment procedures and materials, eligibility criteria and clinician-rated outcome measures. DIALOG + has a potential to increase SQOL and reduce depressive symptoms for service users with chronic depression. ISRCTN16864442 (10.04.2018).