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.