Cost-utility of a new psychosocial goal-setting and manualised support intervention for Independence in Dementia (NIDUS-Family) versus goal-setting and routine care: economic evaluation embedded within a randomised controlled trial.

Background: NIDUS-Family is a 6-8 session, psychosocial and behavioural intervention, delivered by non-clinical facilitators, tailored to goals set by dementia-unpaid/family carer dyads. It is effective in terms of attainment of personalised client goals. We aimed to determine if it is cost-effective. Methods: This cost utility and cost-effectiveness analysis is within a two-armed, single masked, multi-site, superiority Randomised Controlled Trial (RCT). We recruited 302 dyads from community settings. Randomisation was blocked and site-stratified, using a 2:1 ratio (intervention: control (goal-setting and routine care)), with allocation by remote web-based system. We calculated the probability that NIDUS-Family is cost-effective for a client with dementia based on Quality Adjusted Life Year (QALY) from health and personal social services and societal perspectives, at GBP 20,000-30,000 decision thresholds for QALY gained, compared to usual care over 12 months. Analyses were intention-to-treat. Trial registration: ISRCTN11425138. Findings: From 30.4.2020-9.5.2022, 204 participants (109 (53.4%) female) were randomised to intervention and 98 (60 (61.2%) female) to control. 218 (72.2%) participants at 6 months and 178 (58.9%) at 12 months provided cost data. There was 89% and 87% probability that NIDUS-Family was cost-effective compared to usual care from personal social services and societal perspectives respectively. Intervention participants accrued on average GBP 8934 (37%) less costs than control participants (95% CI -59,460 to 41,592). Interpretation: NIDUS-Family is the first personalised care and support intervention to demonstrate cost-effectiveness from the perspective of the quality of life of people with dementia, as well as clinical effectiveness and should be part of routine dementia care.