Age at onset and the outcomes of schizophrenia: A systematic review and meta‐analysis

The aim of this study was to analyse the effect of age at onset on the long-term clinical, social and global outcomes of schizophrenia through a systematic review and a meta-analysis. Original studies were searched from Web of Science, PsycINFO, Pubmed and Scopus, as well as manually. Naturalistic studies with at least a 2-year follow-up were included. Of the 3509 search results, 81 articles fulfilled the inclusion criteria. The meta-analysis was performed in Stata as a random-effect analysis with correlation coefficients between age at onset and the outcomes (categorized into remission, relapse, hospitalization, positive symptoms, negative symptoms, total symptoms, general clinical outcome, employment, social/occupational functioning and global outcome). There was a statistically significant (P < .05) correlation between younger age at onset and more hospitalizations (number of studies, n = 9; correlation, r = 0.17; 95% confidence interval, CI 0.09-0.25), more negative symptoms (n = 7; r = 0.14; 95% CI 0.01-0.27), more relapses (n = 3; r = 0.11; 95% CI 0.02-0.20), poorer social/occupational functioning (n = 12; r = 0.15; 95% CI 0.05-0.25) and poorer global outcome (n = 13; r = 0.14; 95% CI 0.07-0.22). Other relationships were not significant. This was the first systematic review of the effects of age at onset on the long-term outcomes of schizophrenia. The results show that age at onset has a small, but significant impact on some of the outcomes of schizophrenia.