Evaluation of the London Smoking Cessation Transformation Programme: a time–series analysis

BACKGROUND AND AIM: National social marketing campaigns have been shown to promote smoking cessation in England. There is reason to believe that regional and city‐wide campaigns can play a valuable role in reducing smoking prevalence over and above any national tobacco control activity. This study aimed to assess the impact of the London Smoking Cessation Transformation Programme, a multi‐component citywide smoking cessation programme, on quit attempts and quit success rates. DESIGN AND SETTING: Interrupted time–series analyses, using Autoregressive Integrated Moving Average (ARIMA) and generalized additive models (GAM) of population trends in the difference between monthly quit attempts and quit success rates among smokers who made a quit attempt in London versus the rest of England before and during the first year of the programme. PARTICIPANTS: A total of 55 528 past‐year adult smokers who participated in a monthly series of nationally representative cross‐sectional surveys in England between November 2006 and August 2018. Twelve and a half per cent of smokers lived in London (intervention region) and 87.5% lived in the rest of England (control region). MEASUREMENTS: Monthly prevalence of quit attempts and quit success rates among smokers who made a quit attempt. FINDINGS: The monthly difference in prevalence of quit attempts in London compared with the rest of England increased by 9.59% [95% confidence interval (CI) = 4.35–14.83, P < 0.001] from a mean of 0.04% pre‐intervention to 9.63% post‐intervention. The observed increase in success rates among those who tried was not statistically significant (B = 4.72; 95% CI = –2.68 to 12.11, P = 0.21); Bayes factors indicated that these data were insensitive. GAM analyses confirmed these results. CONCLUSION: The promotion of the London Smoking Cessation Transformation Programme during September 2017 was associated with a significant increase in quit attempts compared with the rest of England. The results were inconclusive regarding an effect on quit success among those who tried.