INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .
Relationship between relapse and hospitalization in first-episode psychosis.
OBJECTIVE Relapse is a frequently used outcome measure in schizophrenia research . However , difficulties in reliably measuring relapse diminish its usefulness . Hospitalization is a potential alternative , but its relationship to relapse has not been assessed . METHODS This study used data from a two-year , prospect i ve study to examine associations between  relapse  and  hospitalization  in a cohort of 200 Canadian patients with first-episode psychosis . First , the relationship between relapse and  hospitalization  was assessed by cross-tabulating relapse and hospitalization . Next , survival curves of time to first relapse or hospitalization were compared . Finally , to examine the convergent validity of relapse and  hospitalization  , the predictive capacity of three predictors were examined : a substance use disorder diagnosis , prior hospitalization , and medication adherence . RESULTS Rates of both relapse and hospitalization were similar . During the two-year follow-up , 37 % of the patients experienced a relapse , and 26 % were hospitalized . As an indicator of relapse , hospitalization had a low sensitivity ( 47 % ) and high specificity ( 87 % ) . A higher risk of hospitalization and relapse was associated with prior hospitalization , a substance use disorder diagnosis , and medication nonadherence . CONCLUSIONS Results indicated that relapse and hospitalization are separate but related outcome measures . They had similar frequencies and were found to have similar relationships with some predictors . Relapse is a more useful outcome measure in smaller clinical studies in which routine st and ardized clinical measures can be used .  Hospitalization  is more relevant in larger studies or as a quality indicator for studies using administrative data bases , and it serves as a good measure for quality management in health systems
INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .