The Association Between Cannabis Dependence and Tobacco Smoking Cessation in a Representative U.S. Sample

Introduction: Studies indicate that almost half of cannabis (marijuana) users also smoke tobacco. Cannabis users have a higher rate of smoking compared to the general population. The dual use of cannabis and tobacco presents a significant barrier to cessation of either substance. However, not all cannabis users are dependent on it. In this paper, we describe the association between cannabis dependence and smoking cessation using data from a nationally representative U.S. sample.

Methods: This study used data from the 2012 National Survey of Drug Use and Health (NSDUH), representative sample of the non-institutionalized U.S. population. Variables measured in the survey include use of tobacco, alcohol, illicit drugs, mental health status and demographics of respondents. The sample for the current analysis consisted of adults aged 18 and over (N = 10,135). In the current analyses, 47% of the sample were female. Among cannabis users, approximately 60% used cigarettes in the past month. This figure increased to 64% among people who were classified as cannabis dependent.    

We computed smoking cessation status from the NSDUH questions on lifetime smokers and smoking the 30 days prior to the NSDUH interview. Conventionally, individuals who have smoked more than 100 cigarettes in their lifetime are labeled as "lifetime smokers".  Drawing from the literature, we defined a former smoker as a lifetime smoker who had not smoked in the 30 days prior to the NSDUH interview (Smoking cessation: Yes). A current smoker is a lifetime smoker who had smoked at any time in the preceding 30 days (Smoking cessation: No). The NSDUH asked a number of questions on the use and effects of cannabis on health and social functioning. Based on this, the NSDUH created a binary variable on whether or not an individual was cannabis dependent. Logistic regression models were used to examine the relationship between cannabis dependence and smoking cessation. Point estimates were appropriately weighed and standard errors were adjusted to account for the complex survey design. All analyses were conducted using STATA version 13.

Results: The results from the logistic regression showed that people who were cannabis dependent were 82% less likely to quit smoking compared to people who were not cannabis dependent (OR=0.18, CI=0.12-0.28). Stratified analyses examining only females indicated those who were cannabis dependent were 79% less likely quit smoking compared to non-cannabis dependent females (OR=0.21, CI=0.10-0.43). An analysis of the data for only males indicated a similar trend (OR=0.17, CI=0.10-0.29).

Conclusion: Individuals who are dependent on cannabis are less likely quit smoking compared to those who are non-cannabis dependent. This study has potential implications for prevention science. Addressing cannabis dependence could contribute to successful smoking cessation among users of both substances.