A substantial proportion of people at clinical high risk of psychosis will develop a psychotic disorder over time. However, the risk of transition to psychosis varies between centers, and some recent work suggests that the risk of transition may be declining.
To quantitatively examine the literature to date reporting the transition risk to psychosis in subjects at clinical high risk.
The electronic databases were searched until January 2011. All studies reporting transition risks in patients at clinical high risk were retrieved.
Twenty-seven studies met the inclusion criteria, comprising a total of 2502 patients.
Transition risks, as well as demographic, clinical, and methodologic variables, were extracted from each publication or obtained directly from its authors.
There was a consistent transition risk, independent of the psychometric instruments used, of 18% after 6 months of follow-up, 22% after 1 year, 29% after 2 years, and 36% after 3 years. Significant moderators accounting for heterogeneity across studies and influencing the transition risks were the age of participants, publication year, treatments received, and diagnostic criteria used. There was no publication bias, and a sensitivity analysis confirmed the robustness of the core findings.
The state of clinical high risk is associated with a very high risk of developing psychosis within the first 3 years of clinical presentation, and the risk progressively increases across this period. The transition risk varies with the age of the patient, the nature of the treatment provided, and the way the syndrome and transition to psychosis are defined.