Results
61 studies comprising 72 samples were analysed appendix. 7475 people with psychosis were
smokers and 5670 people with psychosis were non-smokers shows the prevalence of smoking in people presenting with their first episode of psychosis. 34 samples were analysed,
from 34 studies In the total sample of smokers, prevalence of smoking in people
presenting with their first episode of psychosis was 0∙57. Between-sample heterogeneity was significant, with an I² of 88·0%. All definitions of smoking (including daily smoking)
were included in our analysis of smoking prevalence in people presenting with their first episode of psychosis. 12 samples were obtained for the analysis, from 11 casecontrol
studies.Compared with controls, the overall prevalence of smoking in people presenting with
their first episode of psychosis was three times higher. Between-sample heterogeneity was significant, with an I² of 82·1%. Findings of Begg’s test (p=0∙007) and Egger’s
test (p=0∙018) suggested that publication bias might have been present. In the analysis of daily smoking status, four samples were identified, from three studies, with an overall odds ratio of 1∙01. Between-sample hetero geneity was significant, with an I² of 53·3%.