Cannabis as Secondary Drug Is Not Associated With a Greater Risk of Death in Patients With Opiate, Cocaine, or Alcohol Dependence.

Abstract

The health burden of cannabis use in patients with other substance dependencies is not fully understood. To assess the impact of cannabis use as secondary drug on mortality of patients with other major substance use disorders. Patients with opiate, cocaine, or alcohol dependence admitted to detoxification from 2001 to 2010 at a teaching hospital in Badalona, Spain. Sociodemographic characteristics, drug use, medical comorbidities, and urine drug screens were obtained at admission. Deaths were ascertained through clinical records and a death registry. Mortality rates and Cox regression models were used to analyze the association between urinary cannabis and mortality. A total of 474 patients (20% women) were admitted with a median age of 38 years (interquartile range: 32-44 years). The main substances that motivated admissions were opiates (27%), cocaine (24%), and alcohol (49%). Positive urinary cannabis was detected in 168 patients (35%). Prevalence of cannabis use among patients with opiate, cocaine, or alcohol dependence was 46.5%, 42.9%, and 25.5%, respectively. At admission, 110 (23.7%) patients had human immunodeficiency virus infection and 217 (46.5%) had hepatitis C virus infection. Patients were studied for a median of 5.6 years (interquartile range: 2.6-7.7 years) (2454.7 person-years), and at the end of the study, 50 patients (10.5%) had died, yielding a mortality rate of 2.04 × 100 patient-years (95% confidence interval: 1.53-2.66). There was no association between cannabis detection and overall mortality in the adjusted regression models [hazard ratio (95% confidence interval): 1.12 (0.60-2.00), P = 0.73], but acquired immune deficiency syndrome-related deaths were more frequent in those positive for cannabis (26% vs 2%, P = 0.03). Positive urinary cannabis did not confer an increased risk of death in patients with severe opiate, cocaine or alcohol dependence.