Cost-effectiveness of adding a smartphone app (BlueIce) to the mental health care of adolescents who repeatedly self-harm.

Digital interventions can offer crises support although their cost-effectiveness is unknown. We undertook an economic evaluation alongside a two-arm, single blind, randomised controlled trial. 170 adolescents aged 12-17, receiving child and adolescent mental health care who had self-harmed ≥2 in the past 12 months were randomised to usual care with or without an app (BlueIce). The Risk-Taking and Self-Harm Inventory for Adolescents (RTSHIA), and Child Health Utility 9-Dimensions (CHU-9D) were completed at baseline, 12-weeks, and 6-months. Mental healthcare use was extracted from clinical records. CHU-9D responses were converted to preference-based utility values to estimate quality-adjusted life-years (QALYs). Generalised linear models examined the effect of BlueIce from the NHS and Personal Social Services perspective on costs and QALYs. The cost of BlueIce was £32.26 with the mean cost of mental healthcare over 6 months ranging between £1750 - £2472 per participant. The 6-month difference in mean costs [-£722.09 (95 % CI:1998.84, 334.65)] and the utility score [0.009 (95 %CI:0.033, 0.052)] both favoured BlueIce. Youth derived QALYs showed an incremental net monetary benefit (NMB) at 6-months of £782.09 with an almost 70 % probability of being cost-effective. Given the low intervention cost, the addition of an app could be considered a good investment.