Assessing the overlap between tobacco and marijuana: Trends in patterns of co-use of tobacco and marijuana in adults from 2003-2012.

BACKGROUND As marijuana legalization and acceptability increase in the U.S., it is important to understand the potential impact on tobacco use. Accordingly, we assessed prevalence, correlates, and ten-year trends in co-use of marijuana and tobacco among U.S. adults. METHODS Data came from 378,459 adults participating in the 2003-2012 National Survey on Drug Use and Health, an annual, cross-sectional, household survey. Data from 2011-2012 were used to compute the most recent prevalence of past 30-day marijuana and tobacco use (co-use). Data from 2003-2012 were used to compute demographic correlates of co-use, overall trends in co-use, and trends by age, race, and sex. We also assessed trends in tobacco use among marijuana users and marijuana use among tobacco users. RESULTS From 2011 to 2012, 5.2% of participants were past month co-marijuana and tobacco users, 24.0% were tobacco-only users, and 2.3% were marijuana-only users. From 2003 to 2012, prevalence of co-use increased overall (p<.0001), and among males and females (p<.001, p<.05), those ages 26-34 (p<.001) and 50+years (p<.0001), and Whites (p<.01), Blacks (p<.05), and Hispanics (p<.01); there were no changes among adults 18-25 years. Tobacco use among marijuana users decreased between 2003 and 2012 (from 74.3% to 69.6%, p<.0001), while marijuana use increased among tobacco users (from 14.2% to 17.8, p<.0001). CONCLUSIONS Co-use of tobacco and marijuana increased from 2003-2012, with marijuana use increasing among past-month tobacco users and tobacco use declining among past-month marijuana users. Improved surveillance of co-use is needed as marijuana legalization policies expand and become more integrated in communities.