Outreach and support in south London (OASIS), 2001-2011: ten years of early diagnosis and treatment for young individuals at high clinical risk for psychosis.

INTRODUCTION: Prevention of psychosis has become a major objective of modern clinical psychiatry. An increasing number of new services have been established in Europe and in the world. The OASIS team has become an established model where clinical practice and research are fully integrated in the field of preventative interventions in psychosis.
METHOD: Comprehensive analysis of different clinical and service measures describing the 2001-2011 implementation of the OASIS team.
RESULTS: Over the last decade, the OASIS team has received a total of 1102 referrals, mostly young males from ethnic minorities. After the assessment, 35% were diagnosed with an At Risk Mental State (ARMS) while 32% were already psychotic. Within the ARMS, 70% met the inclusion criteria for the attenuated psychotic symptoms subgroup, 1% met the inclusion criteria for the genetic deterioration syndrome, 9% met inclusion criteria for a brief and self-limited intermittent psychotic episode and the others met inclusion criteria for more than one subgroup. Most of them had at least one comorbid diagnosis, mainly relating to anxiety and depressive domains. The majority of the OASIS clients received cognitive behavioural therapy alone or in combination with antidepressants/antipsychotics. Over the 2-year follow-up time, 44 subjects (15.2%) developed a frank psychotic episode.
CONCLUSIONS: The OASIS service represents one of the largest and most established prodromal services in the world. The burden of research evidence and the translational impact produced on the clinical practice support the OASIS as a model for the development of similar services.