Abstract
INTRODUCTION: Tobacco smoking remains the leading cause of preventable death worldwide. Smoking reduction can be recommended to people unmotivated to quit, but evidence on trajectories of reduction and associated outcomes is mixed.
METHODS: In a secondary analysis of five randomised, placebo-controlled trials of nicotine replacement therapy, we used latent class analysis and elastic net regression to determine latent smoking trajectories using cigarettes-per-day (CPD) across 26 weeks. Participants were adults who smoked daily without intention to quit in the next month. We used predictive modelling and receiver operator characteristic area under-the-curve (AUC) to assess smoking cessation after 1 year.
RESULTS: Participants (n=2066) smoked a mean 27.26±9.74 CPD at baseline. Three distinct smoking patterns emerged: Class 1 (n=186, 10%) achieved the greatest reduction in CPD (2-week mean 57% reduction) with subsequent reduction; Class 2 (n=803, 45%) saw a 2-week mean 50% reduction and remained at that level and Class 3 (n=794, 45%) reduced by a 2-week mean of 22% and returned to near-baseline CPD. Older, male participants with lower anxiety and lower nicotine dependence were more likely to be in Class 1. Abstinence rates at 1 year (~50 weeks after reduction) were 37.6% for Class 1, 4.2% for Class 2 and 2.3% for Class 3.Using latent class assignment as a predictor improved prediction of smoking cessation at 1 year follow-up over prediction using baseline characteristics by 14.4% (AUC=0.776±0.010, p=0.002). Those who reduced their CPD minimally were nearly 90% less likely to achieve cessation than those who reduced by over 50% (ORs: Class 2=0.111±0.013, Class 3=0.070±0.005).
CONCLUSIONS: Findings suggest adults who are unmotivated to quit at baseline but reduce their smoking by more than half are most likely to achieve smoking cessation. A lack of early reduction success could indicate that greater support is needed to help people to quit.
| Original language | English |
|---|---|
| Article number | e001605 |
| Number of pages | 10 |
| Journal | BMJ Public Health |
| Volume | 3 |
| Issue number | 2 |
| Early online date | 25 Dec 2025 |
| DOIs | |
| Publication status | Published - 25 Dec 2025 |
Data Availability Statement
Data are available upon reasonable request. Requests should be made to the corresponding author.Funding
This work was supported by the National Institute on Drug Abuse and the National Institute of General Medical Sciences at the National Institutes of Health (grant numbers T32DA045593 to AB, P30GM149331 to EK); the Prevention and Population Research Committee and a Population Researcher Postdoctoral Fellowship Award from Cancer Research UK (grant numbers PPRCPJT\100,023 to GT, C56067/A21330 to GT).
