Seventy seven percent of the patients in this study reported a lifetime history of substance or alcohol use. The two most commonly used substances were alcohol and cannabis. After controlling for age, sex, smoking status and alcohol use in the cox model, we observed a lower mortality risk adjusted variable in cannabis-users compared to cannabis non-users despite subjects having similar symptoms and antipsychotic treatment. It is surprising that the GAF in lifetime users and non-users of cannabis or alcohol users was not significantly different. This may be due to the fact that GAF is a subjective measurement and it was only a one time cross-sectional assessment. Although not significant in the Cox model, when stratified into four groups, those using alcohol in the older age group had significantly higher mortality in the Kaplan-Meier survival curve. This finding may be driven by the age factor.
