INTRODUCTION: Specialized early intervention programs such as The Danish OPUS treatment are efficient in treating patients with a first episode of psychosis (FEP) at least after 2 and 5 years. Few studies have examined long-term outcomes of these interventions.

AIM: To examine the effect of 2 years of OPUS vs treatment as usual (TAU) within an FEP cohort, 10 years after inclusion into the OPUS trial.

METHODS: From 1998 to 2000, participants were randomized to OPUS or TAU. Ten years later, we conducted comprehensive interviews and performed register-based follow-up on all participants in national Danish registers. We analyzed participants according to the intention-to-treat principle.

RESULTS: Of the 547 participants included in the study, 347 (63.4%) took part in this follow-up. While there was evidence of a differential 10-year course in the development of negative symptoms, psychiatric bed days, and possibly psychotic symptoms in favor of OPUS treatment, differences were driven by effects at earlier follow-ups and had diminished over time. Statistically significant differences in the course of use of supported housing were present even after 8-10 years. There were no differences between OPUS and TAU regarding income, work-related outcomes, or marital status.

CONCLUSION: Most of the positive short-term effects of the OPUS intervention had diminished or vanished at this long-term follow-up. We observed a clear tendency that OPUS treatment leads to fewer days in supported housing. There is a need for further studies investigating if extending the intervention will improve outcomes more markedly at long-term follow-ups.