Title: Investigating within-person patterns and trajectories of dual e-cigarette and tobacco use: a mixed methods study
Funder: Cancer Research UK

Abstract: Background: The full benefits of switching to e-cigarettes for cancer reduction are only realised if complete abstinence from tobacco occurs, however, around half of UK e-cigarette users continue to smoke tobacco. Although this dual use behaviour is common, it is poorly understood. Patterns of dual use vary widely, from regular e-cigarette use with occasional tobacco smoking to mixed daily use of both products. Factors precipitating dual use also vary. Given this heterogeneity, a repeated measures within-subjects investigation will provide a detailed assessment of individual dual use patterns and which factors predict trajectories of e-cigarette and/or tobacco use. Aims: 1) To investigate within-person patterns and trajectories of dual use behaviour and how this varies between individuals. 2) To identify within-person predictors of patterns of use. 3) To understand participant perspectives on their dual use behaviour. Methodology: A mixed methods N-of-1 study purposively sampling dual users (N=20) based on a range of nicotine dependence, socioeconomic status and patterns of dual use. Participants will complete repeated (daily) measures for three months under naturalistic conditions on their e-cigarette use (objective and self-report), self-reported tobacco use, and on theory-informed psychological, social and environmental factors that are potential predictors of e-cigarette and tobacco behavioural patterns. To address aim 1 we will generate descriptives of both intra- and inter-individual dual use patterns and trajectories, identifying individual time trends using trend analysis (using Generalized Additive Mixed Models [GAMM]). For aim 2, we will assess predictors of short-term episodes of exclusive tobacco use, relapse to exclusive tobacco use and full switching to exclusive e-cigarette use using GAMM. For aim 3 we will use qualitative interviews prompted by a summary report of each participant’s data to explore their perspectives on their patterns of use. Findings will be combined at an interpretation level to provide a detailed account of patterns and trajectories of dual use behaviour over time. Results: The findings will help inform a typology of dual use with situated, person-centred explanations for changes over time. Ultimately, the project will contribute to and guide policy and practice decisions and the development of interventions to support dual users to use e-cigarettes exclusively and avoid smoking relapse. Findings are anticipated to be of high interest to the Stop Smoking Services who increasingly report e-cigarette use among their clients. This work will also inform future research activities to improve our understanding of how to support dual users to become tobacco free.

Lay abstract: Background: The full benefits of switching to e-cigarettes for cancer reduction are only realised if complete abstinence from tobacco occurs, however, around half of UK e-cigarette users continue to smoke tobacco. Although this dual use behaviour is common, it is poorly understood. Patterns of dual use vary widely, from regular e-cigarette use with occasional tobacco smoking to mixed daily use of both products. Factors precipitating dual use also vary. Given this heterogeneity, a repeated measures within-subjects investigation will provide a detailed assessment of individual dual use patterns and which factors predict trajectories of e-cigarette and/or tobacco use. Aims: 1) To investigate within-person patterns and trajectories of dual use behaviour and how this varies between individuals. 2) To identify within-person predictors of patterns of use. 3) To understand participant perspectives on their dual use behaviour. Methodology: A mixed methods N-of-1 study purposively sampling dual users (N=20) based on a range of nicotine dependence, socioeconomic status and patterns of dual use. Participants will complete repeated (daily) measures for three months under naturalistic conditions on their e-cigarette use (objective and self-report), self-reported tobacco use, and on theory-informed psychological, social and environmental factors that are potential predictors of e-cigarette and tobacco behavioural patterns. To address aim 1 we will generate descriptives of both intra- and inter-individual dual use patterns and trajectories, identifying individual time trends using trend analysis (using Generalized Additive Mixed Models [GAMM]). For aim 2, we will assess predictors of short-term episodes of exclusive tobacco use, relapse to exclusive tobacco use and full switching to exclusive e-cigarette use using GAMM. For aim 3 we will use qualitative interviews prompted by a summary report of each participant’s data to explore their perspectives on their patterns of use. Findings will be combined at an interpretation level to provide a detailed account of patterns and trajectories of dual use behaviour over time. Results: The findings will help inform a typology of dual use with situated, person-centred explanations for changes over time. Ultimately, the project will contribute to and guide policy and practice decisions and the development of interventions to support dual users to use e-cigarettes exclusively and avoid smoking relapse. Findings are anticipated to be of high interest to the Stop Smoking Services who increasingly report e-cigarette use among their clients. This work will also inform future research activities to improve our understanding of how to support dual users to become tobacco free.

Research activity codes: 3.1 PRIMARY PREVENTION INTERVENTIONS TO MODIFY BEHAVIOURS OR PROMOTE WELL-BEING
Health categories: CANCER AND NEOPLASMS;CARDIOVASCULAR;RESPIRATORY;STROKE