BACKGROUND AND AIMS

Varenicline is one of the most effective smoking cessation treatments. Its supply in England was disrupted in July 2021 due to nitrosamine impurities found by its supplier, Pfizer. This study measured the impact of this disruption on smoking cessation in England.

DESIGN, SETTING AND PARTICIPANTS: The study used repeated cross-sectional surveys conducted monthly, from June 2018 to December 2022. Set in England, it comprised a total of 3024 adults who reported smoking during the past year and had made at least one serious attempt to quit in the past 6 months.

MEASUREMENTS

Generalized additive models analyzed the association of the varenicline supply disruption with the trend in self-reported varenicline use in the most recent quit attempt. We used these results to estimate the population-level impact of the disruption on smoking cessation.

FINDINGS

Before July 2021, the proportion of past 6-month quit attempts using varenicline was stable at approximately 3.9% [risk ratio (RR) = 1.034, 95% confidence interval (CI) = 0.823-1.298]. The trend in varenicline use has changed sharply since the supply disruption (RR = 0.297, 95% CI = 0.120-0.738), with prevalence falling by 69.3% per year since; from 4.1% in June 2021 to 0.8% in December 2022. Convergently, National Health Service general practitioner prescribing data reported that just 0.1% of prescriptions for smoking cessation treatments in December 2022 were for varenicline. Assuming that varenicline does not return to the market, we estimate that this could result in ~8400 fewer people stopping smoking for at least 6 months, ~4200 fewer long-term ex-smokers and ~1890 more avoidable deaths each year.

CONCLUSIONS

In England, the disruption in supply of varenicline since 2021 has coincided with a substantial fall in the use of varenicline in attempts to quit smoking.