Accurate and sufficient measurement of cannabis and tobacco co-use: Agreement, consensus, and the path forward

Abstract

Expert consensus surrounding cannabis-tobacco co-use measurement is critical and necessary in providing a harmonized data bank to those interested in measuring co-use but require expert recommendations. The need for consensus signifies the next step forward in the accurate and sufficient measurement of cannabis-tobacco co-use to improve public health efforts.

Hindocha & McClure (1) argued for better measurement of cannabis and tobacco co-use at multiple levels of investigation (e.g., clinical studies, clinical care, surveillance), as there may be unknown harms associated with co-use. We appreciate the insightful responses generated from experts in the field, and feel that collectively, this Debate series supports the need to develop a path forward for co-use measurement consensus and implementation.

McRobbie et al. (2) note important considerations for those weighing the pros and cons of additional assessment to capture co-use and note the areas of public health and research that could benefit from co-use measurement. One underlying theme throughout McRobbie et al.’s response pertains to individual differences in co-use patterns not currently being assessed. Temporarily of use, price sensitivity to products and substitution potential, patterns of co-use, such as blunt use and co-administration, subjective and health effects of co-use, and treatment implications are all complex and multi-faceted issues that likely vary across individuals who co-use substances. Without accurate measurement of co-use, we are unable to document these individual differences and respond accordingly.

Walsh & Duaso (3) argue that co-use measurement is essential for treatment interventions and clinical care. Practitioners, experienced in screening and treating tobacco use, would benefit from clear recommendations on cannabis screening, data capture, and when use emerges, how to address and intervene, particularly among a tobacco-using population. Walsh & Duaso also highlight the issue of cannabis legality across geographic regions and how that may affect honesty in patient endorsement, reporting requirements for the provider, and implications for documentation of illicit substance use. These are critical challenges to the wide-scale integration of cannabis use capture into clinical care and among those treating tobacco use.

Finally, Najman (4) highlights how quickly the landscape of nicotine/tobacco and cannabis use are evolving, allowing for increased access to an array of products that are not easily captured through current research and surveillance instruments. Further, polysubstance use is common, and combinations of substances used together require additional attention, with cannabis and tobacco co-use being one example. Najman argues for innovation in research methods to capture data from large samples with the goal of better assessment of polysubstance use patterns.

Taken together, these thought-provoking and timely responses are diverse in theme, though in overwhelming agreement that cannabis-tobacco co-use is an important public health concern that requires better measurement. The next logical step forward then is consensus building of terms and items to capture co-use accurately and sufficiently. This is complex given the rapidly shifting regulatory landscapes of cannabis and tobacco, which operate independently and vary across geographic regions. This is problematic for these substances, more so than for many other substances given the commonality of use.

While challenging, McRobbie et al.’s response (2) points out that lessons may be learned from recent efforts to build consensus of novel tobacco and nicotine product terminology (5) as well as employing methods used for item determination and expert consensus, such as the Delphi Method. There is appreciable burden associated with additional data collection, particularly in clinical care, and as such, the path forward should include consensus and recommendation of data element tiers (1) based on the research question and goals of inclusion. We intentionally recommended categories of data elements as part of tiered recommendations but did not provide specific items and wording. The task of consensus building will require expert input, time, and effort, though it is worthwhile and timely. Distilling co-use down to one or two pertinent items that are informative and predictive of outcomes, as a starting point, would be beneficial. For those interested in tobacco cessation research and service delivery, for example, they may seek out a single item to capture cannabis use among their patients to accurately account for co-use. However, consensus does not currently exist to suggest what single item would be recommended in this setting.

In conclusion, the field requires consensus in the terms that are used for tobacco/nicotine use, cannabis use, and importantly, their co-use, which is true of the substance use field more broadly (6). Consensus surrounding co-use measurement is critical and necessary to provide a harmonized data bank to researchers, clinicians, epidemiologists, and others interested in incorporating these items, but who rely on expert recommendations. The need for consensus signifies the next step forward in the accurate and sufficient measurement of cannabis-tobacco co-use to improve public health efforts.