Evaluation of a Regional Tobacco Control Program (Greater Manchester's Making Smoking History) on Quitting and Smoking in England 2014-2022: A Time-Series Analysis.

Introduction: This study aimed to assess the impact of Greater Manchester's Making Smoking History program-a region-wide smoking cessation programs launched in January 2018-on key smoking and quitting outcomes.

Methods: Data were from a nationally representative monthly survey, 2014-2022 (n = 171 281). We used interrupted time-series analyses (Autoregressive Integrated Moving Average [ARIMA] and generalized additive models [GAM]) to examine regional differences between Greater Manchester and the rest of England, before and during the program's first five years. Outcomes were rates of quit attempts and overall quits among smokers, quit success rates among smokers who tried to quit (preregistered outcomes), and current smoking prevalence among adults (unregistered outcome).

Results: Results showed mixed effects of the program on quitting. Primary ARIMA models showed comparative reductions in quit success rates (change in quarterly difference between regions = -11.03%; 95% CI -18.96; -3.11) and overall quit rates in Greater Manchester compared with the rest of England (-2.56%; 95% CI -4.95; -0.18), and no significant change in the difference in the quit attempt rate (+2.95%; 95% CI -11.64; 17.54). These results were not consistently observed across sensitivity analyses or GAM analyses. Exploratory ARIMA models consistently showed smoking prevalence in Greater Manchester declined more quickly than in the rest of England following the initiation of the program (-2.14%; 95% CI -4.02; -0.27).

Conclusions: The first five years of Greater Manchester's Making Smoking History program did not appear to be associated with substantial increases in quitting activity. However, exploratory analyses showed a significant reduction in the regional smoking rate, over and above changes in the rest of England over the same period.

Implications: Taken together, these results show a relative decline in smoking prevalence in Greater Manchester but equivocal data on quitting, introducing some uncertainty. It is possible the program has reduced smoking prevalence in the absence of any substantial change in quitting activity by changing norms around smoking and reducing uptake, or by reducing the rate of late relapse. It is also possible that an undetected effect on quitting outcomes has still contributed to the program's impact on reducing prevalence to some degree. It will be important to evaluate the overall impact of the program over a longer timeframe.