JMIR Publications

ABSTRACT

Background:

Smoking cessation trials typically report the average treatment effects, in which causal inference is made regarding the average effect of a treatment on a heterogeneous sample. Nonetheless, individual factors such as age, gender, and genetics can impact the effectiveness of a treatment on outcomes.

Objective:

This study aimed to estimate the individualised effects of a text-message based smoking cessation intervention.

Methods:

Data from a randomised controlled trial including 1012 adults from the Swedish general population were used. The trial assessed the effects of a text-messaging intervention that aimed to change behaviour by increasing the importance for change, boosting knowledge on how to change, and instilling confidence for change. Outcomes were prolonged abstinence and point-prevalence of smoking cessation. Individualised treatment effects were modelled using baseline factors to study who benefitted the most from the intervention.

Results:

There was evidence of heterogenous effects with those benefitting the most being older individuals, those with planned surgery, those who smoked less and had done so for a shorter duration, those with high confidence in their ability to quit, and those who believed that quitting was important.

Conclusions:

The results demonstrate how individuals respond differently to a text-message smoking cessation intervention. This provides an insight into who benefits the most and least from the intervention and highlights who needs to be targeted in future interventions to further the reduce the prevalence of smoking. Clinical Trial: The trial was registered in the ISRCTN registry on 03/12/20 (ISRCTN13455271).