JMIR Publications

ABSTRACT

Background:

Digital technologies offer potential for low-cost, scalable delivery of interventions to promote smoking cessation.

Objective:

To evaluate the effectiveness of the offer of Smoke Free – an evidence-informed, widely used app – for smoking cessation versus no support.

Methods:

In this two-arm randomised controlled trial, 3,143 motivated adult smokers were recruited online between August-2020 and April-2021 and randomised to receive an offer of the Smoke Free app plus follow-up (intervention arm) versus follow-up only (comparator arm). Both groups were shown a brief message at the end of the baseline questionnaire encouraging them to make a quit attempt. The primary outcome was self-reported 6-month continuous abstinence assessed 7 months after randomisation. Secondary outcomes included quit attempts in the first month post-randomisation, 3-month continuous abstinence assessed at 4 months, and 6-month continuous abstinence at 7 months among those who made a quit attempt. The primary analysis was performed on an intention-to-treat basis, with missing-equals-smoking imputation. Sensitivity analyses included i) restricting the intervention group to those who took up the offer of the app, ii) using complete cases, and iii) using multiple imputation.

Results:

The effective follow-up rate for 7 months was 41.9%. The primary analysis showed no evidence of a benefit of the intervention on rates of 6-month continuous abstinence (intervention 6.8% vs. comparator 7.0%; RR=0.97, 95%CI=0.75-1.26). Analyses on all secondary outcomes also showed no evidence of a benefit. Similar results were observed on complete cases and using multiple imputation. When the intervention group was restricted to those who took up the offer of the app (n=395, 25.3%), participants in the intervention group were 80% more likely to report 6-month continuous abstinence (12.7% vs. 7.0%; RR=1.80, 95%CI=1.30-2.45). Equivalent subgroup analyses produced similar results on the secondary outcomes. These differences persisted after adjustment for key baseline characteristics.

Conclusions:

Among motivated smokers provided with very brief advice to quit, offer of the Smoke Free app did not have a detectable benefit for cessation compared with follow-up only. However, the app increased quit rates when smokers randomised to receive the app downloaded it. Clinical Trial: ISRCTN85785540.