JMIR Publications

ABSTRACT

Background:

Digital interventions are increasingly used to support smoking cessation. iCoach was a widely available application for smoking cessation, used by 404,551 European smokers. This provided an unique opportunity to investigate the uptake of a freely available digital smoking cessation intervention and its effects on smoking-related outcomes.

Objective:

The objective of this study was to investigate whether there were distinct trajectories of iCoach usage, to examine which baseline characteristics were associated with user groups (based on intensity of usage), and to assess if and how these groups were associated with smoking-related outcomes.

Methods:

Analyses were performed with data from iCoach users who registered between March 2011 and June 2013. Smoking-related data were collected at baseline and every 3 months thereafter, with a maximum of eight follow-ups. First, group-based modelling was applied to detect distinct trajectories of usage. This was done in a subset of steady users who had completed at least one follow-up measurement. Second, ordinal logistic regression was used to assess which baseline characteristics were associated with user group membership. Lastly, generalized estimating equations were used to examine the association between user groups and smoking status, quitting stage, and self-efficacy over time.

Results:

In a subset of n=26,785 steady iCoach users (8.6% of all n=311,567 iCoach users), four distinct user groups were identified: Low (65.1%), Mild (15.3%), Moderate (16.4%) and Intensive (3.2%) users. Older users and users who found it important to quit smoking had a higher odds of more intensive app use, whereas male users, employed users, heavy smokers and users with higher self-efficacy scores, had a lower odds of more intensive app use. User groups were significantly associated with subsequent smoking status, quitting stage, and self-efficacy over time. For all groups, over time the probability of being a smoker decreased, whereas the probability of being in an improved quitting stage increased, as did self-efficacy to quit smoking. For all outcomes, the greatest change was observed between baseline and the first follow-up at 3 months. In the Intensive users the greatest change was seen between baseline and the 9-months follow-up, with observed change declining gradually in the Moderate, Mild and Low users.

Conclusions:

In the subset of steady iCoach users, more intensive app use was associated with higher smoking cessation rates, increased quitting stage and higher self-efficacy to quit smoking over time. These users seemed to benefit most from the app in the first 3 months of use. Female users and relatively older users were more likely to use the app more intensively. Also, users who found quitting difficult made more use of the iCoach app and grew more confident in their ability to quit over time.