Association of Cannabis Use With Cigarette Use in People Certified for Medical Cannabis for Chronic Pain: A Secondary Analysis of a Prospective Cohort Study

Background: Chronic pain is associated with cigarette use and cannabis use and people with chronic pain report using each to manage pain. Little is known about how medical cannabis legalization impacts cigarette use among people with chronic pain. We aimed to examine the relationship between cannabis use and cigarette use in New York State. Methods: Secondary analysis of a prospective, longitudinal cohort study of adults with chronic pain, using opioids and newly certified to use medical cannabis. Quarterly questionnaires over 9 months collected self-reported cannabis use, cigarette use, pain, anxiety and depression. The primary outcome was past 30-day cigarette use [yes/no] and cigarettes per day [CPD]. Four two-step mixed-effect models assessed the longitudinal impact of cannabis on cigarette use. Independent variables for each were cannabis use days in the past 30 days of: (1) any cannabis; (2) cannabis by source (unregulated, medical, mixed); (3) cannabis by route (inhaled, non-inhaled); (4) added interaction between cannabis use and pain severity. Results: Of 223 participants, 75 (33.6%) used cigarettes and 164 (73.5%) used cannabis at baseline. In Model 1, any cannabis use was not significantly associated with cigarette use or CPD. In Model 2, days of unregulated cannabis use (β = .058, P = .002) and mixed cannabis use were associated with CPD (β = .041, P = .018). In Model 3, non-inhaled cannabis use was negatively associated with CPD (β = −.015, P = .015). In Model 4, the interaction term between any cannabis use and pain intensity was significant (β = −.006; P = .047). The association between cannabis use and CPD was positive at pain severity scores less than 6.73, but above it, cannabis use was negatively associated with CPD. Conclusion: Unregulated and non-inhaled cannabis use were implicated in the association between cannabis use and cigarette use, and pain severity moderated the effect of cannabis use on CPD. Further studies are needed to fully understand this relationship.