Qualitative sample size
Following the 6-month assessment period (primary outcome collection), we will include a purposive sample of 20 participants per country, in individual qualitative interviews to discuss their experience of receiving the intervention. The sampling frame will be comprised of all patients randomised to the intervention arm and will explicitly include participants with positive or negative experiences of the intervention, those whose quality of life improved and those whose did not and those who frequently used or who did not receive the intervention during the testing period. Participant characteristics such as age, gender and clinical site (Pakistan) will also be considered. We will also aim to interview all seven clinicians in each country who delivered DIALOG+ to discuss their experiences of delivering the intervention.