Effects of Inhaled Tobacco and Cannabis Co-Use on Respiratory Health and Tobacco Cessation: An Official American Thoracic Society Research Statement

<b>Background:</b> Tobacco and cannabis are among the most widely used substances globally, and rates of co-use are on the rise. Understanding the impact of inhaled tobacco-cannabis co-use on health outcomes and tobacco cessation is critical for guiding patients and clinicians. <b>Objectives:</b> To summarize the existing evidence, identify knowledge gaps, and prioritize research questions related to effects of inhaled tobacco-cannabis co-use on tobacco cessation and lung health. <b>Methods:</b> A multidisciplinary committee was convened to review the evidence, identify knowledge gaps, and develop research questions in four priority research areas: <i>1</i>) common data elements and terminology, <i>2</i>) patterns and prevalence of co-use, <i>3</i>) impact of co-use on tobacco cessation, and <i>4</i>) effects of co-use on lung health. A modified Delphi process was conducted in three rounds to reach consensus on prioritizing research questions. <b>Results:</b> The evidence reviewed by the expert panel in four priority research areas yielded the following gaps in the literature with high priority to address with future research: <i>1</i>) lack of consensus on terminology and recommended co-use data elements, <i>2</i>) limited research on co-use and tobacco-related disparities, <i>3</i>) insufficient evidence on how cannabis use affects tobacco cessation, and <i>4</i>) alarming yet inconsistent findings on the effects of co-use on lung health. <b>Conclusions:</b> This statement outlines and guides a research agenda on the effects of inhaled tobacco-cannabis co-use on tobacco cessation and lung health. Consensus-driven recommendations include adopting harmonized terms and minimum data elements, studying the prevalence of co-use among populations experiencing tobacco-related disparities, evaluating the impact of co-use on tobacco cessation pharmacotherapies, and assessing the effects of co-use on the development and progression of lung diseases.