Background: The outcome of schizophrenia and related psychoses is generally modest, and patients display high rates of disability.
Aims: The aim of the review is to present an up-to-date account of the research on the very long-term outcome of psychotic disorders.
Method: We conducted a search in the PubMed and Scopus databases for articles published since the publication of the very long-term data of the World Health Organization's International Study of Schizophrenia (the ISoS study), over the last 18 years (from 2002 to 2019). Studies were included if they reported on at least 15-year outcome and if they had used valid and reliable tools for the estimation of the patients' outcome in terms of symptomatology and functioning.
Results: A total of 16 studies were included in this review, involving 1,391 patients with schizophrenia and related psychoses. Most were single-center studies, with moderate size samples of patients, and 11 were prospective studies. Very long-term outcome of psychotic disorders varies considerably among studies. Good outcome ranges from 8% to 73.8%, and it appears to be better in developing countries, whereas differences are less apparent among Western countries (8%-40.3%). Studies in different settings have used different methods involving a variety of samples of patients to estimate their outcome, whereas definitions of good and poor outcome also varied among studies. Longer duration of untreated psychosis was associated with worse outcome in some studies. Schizophrenia was found to have poorer long-term prognosis compared to other schizophrenia spectrum disorders. A large proportion of patients, ranging from 19% to 48.2%, were not on medication.
Conclusion: Recent evidence on the very long-term outcome of psychotic disorders is in line with previous reports and suggests that prognosis remains rather modest. There are several limitations of current research regarding outcome definitions and study design that should be addressed by future research.
Keywords: Outcome; psychotic disorders; schizophrenia; very long-term outcome.