Differences in demographic and clinical characteristics between cannabis users and non-drug users: A retrospective study of patients at first hospitalization due to psychotic symptoms

This retrospective, chart review, cohort study compared demographic and clinical characteristics of cannabis -users and non-drug users at first admission due to psychotic symptoms at Geha Mental Health Center, Israel, between August 2002 and December 2013. We assessed the role of current cannabis use as a risk for re-hospitalization during this period as well as the stability of psychotic diagnoses at re-hospitalization. A total of 318 patients were included in the study, of which 106 (33.3%) were cannabis -users. The cannabis-user group had a shorter duration of hospitalization than the non-drug user group but without a significant difference in 5-year re-hospitalization rates. The latter had a higher rate of severe mental illness (SMI) diagnoses at first hospitalization (53.3% vs. 20.3%, respectively), but the difference disappeared at the second hospitalization. The two groups demonstrated a 79–80% rate of conversion from a non-SMI to an SMI diagnosis between the admissions. The results indicate the instability of non-SMI diagnoses at first hospitalization due to psychotic symptoms, regardless of concurrent cannabis use. The high conversion rate from non-SMI to SMI in current cannabis-users may be due to under-diagnosis of SMI at first admission or an effect of cannabis on the development of SMI.