Early intervention in psychosis: health economic evaluation using the net benefit approach in a real-world setting.

Background: Early intervention in psychosis is a complex intervention, usually delivered in a specialist stand-alone setting, which aims to improve outcomes for people with psychosis. Previous studies have been criticised because the control used did not accurately reflect actual practice.

Aims: To evaluate the cost-effectiveness of early intervention by estimating the incremental net benefit (INB) of an early-intervention programme, delivered in a real-world setting. INB measures the difference in monetary terms between alternative interventions.

Method: Two contemporaneous incidence-based cohorts presenting with first-episode psychosis, aged 18-65 years, were compared. Costs and outcomes were measured over 1 year. The main outcome was avoidance of a relapse that required admission to hospital or home-based treatment.

Results: From the health sector perspective, the probability that early intervention was cost-effective was 0.77. The INB was €2465 per person (95% CI - €4418 to €9347) when society placed a value of €6000, the cost of an in-patient relapse, on preventing a relapse requiring admission or home care. Following adjustment, the probability that early intervention was cost-effective was 1, and the INB to the health sector was €3105 per person (95% CI -€8453 to €14 663). From a societal perspective, the adjusted probability that early intervention was cost-effective was 1, and the INB was €19 928 per person (95% CI - €2075 to €41 931).

Conclusions: Early intervention has a modest INB from the health sector perspective and a large INB from the societal perspective. The perspective chosen is critical when presenting results of an economic evaluation of a complex intervention.