Overall of the 762 subjects, 62 died during follow-up. Kaplan-Meier estimates of overall 5- and 10-year mortality risks were 5.8% and 10.6%, respectively. Ten-year mortality risk in patients 35–55 years old at baseline was more than double (13.8%) the 10-year risk in patients under 35 years old at baseline (6.0%) (χ2=11.1, df=1, p=0.0009). In the survival analysis, cannabis users had a lower 5- (3.1%) and 10-year (5.5%) mortality risk than cannabis non-users 5- (7.5%) and 10-year (13.6%) (χ2=8.0, df=1, p=0.005). Similarly, alcohol users had a lower 5- and 10-year mortality risk than alcohol non-users (5-year, 5.5% vs. 6.7%; 10-year, 8.9% vs. 13.1%); however, the differences were not significant (χ2=1.8, df=1, p=0.18). After stratifying by age <35 years versus age 35–55 years, these trends toward reduced mortality in alcohol or cannabis users, compared to non-users remained the same. After excluding cannabis or alcohol users, there were only 11 deaths in subjects using all of the other illicit drug groups listed; therefore, these substances were not included in the subsequent survival analysis. No significant differences in cause specific mortality by alcohol or substance use was detected.
