BACKGROUND AND AIM: Relapse risk among people who formerly smoke is influenced by task difficulty. Cessation fatigue (CF) may be a better predictor than measures such as reported strength of urges to smoke (SUTS) and abstinence self-efficacy (ASE). It may also be affected by quit length and use of other nicotine products. The current study investigated whether post-quitting CF predicts higher relapse risk, its predictive utility relative to ASE and SUTS and whether the CF-relapse prediction was moderated by time since quitting.

DESIGN: Data drawn from longitudinal cohort surveys conducted between 2016 and 2022 of the International Tobacco Control Four Country Smoking and Vaping Survey.

SETTING: Canada, the United States, England and Australia.

PARTICIPANTS: People aged 18 + years who formerly smoked (n = 1914).

MEASUREMENTS: Generalised estimating equations logistic regression models were used to test for associations and moderation.

FINDINGS: In separate individual analyses, CF, ASE and SUTS were statistically significant independent relapse predictors; however, when analysed together, CF was the only statistically significant relapse predictor [moderate CF: odds ratio (OR) = 1.64, 95% confidence interval (CI) = 1.21-2.23, P = 0.002; high CF: OR = 1.81, 95% CI = 1.07-3.07, P = 0.027) on top of continuing main effects of vaping and time since quitting, but time since quitting was not a moderator.

CONCLUSIONS: Cessation fatigue appears to predict smoking relapse risk better than other measures related to task difficulty and does so independently of vaping and time since quitting, which are both protective.