Introduction:
Given low intervention rates in smokers, we tried to assess the effectiveness of an evidence-based intervention to cease smoking via a chatbot in the smartphone compared to usual clinical practice in primary care.

Material and Methods:
Pragmatic randomized clinical trial in 34 primary healthcare centers within the Madrid Health Service. Smokers over 18 years who attended on-site consultation and accepted help to quit tobacco were recruited by their doctor or nurse and randomly allocated to receive usual care (control group, CG) or an evidence-based chatbot intervention (intervention group, IG). Both arms were based on the 5A´s by the US clinical practice guideline, Primary outcome was continuous abstinence from smoking that was biochemically validated after 6 months. The outcome analysis was blinded to allocation of subjects although participants were unblinded to group assignment. An intention-to-treat analysis, in cases of missing data, and logistic regression models were employed for assessing the primary outcomes.

Results:
The trial was conducted between October 1st of 2018 and March 31st of 2019. The sample comprised 513 patients (242 in the IG and 271 in the CG), with an average age of 49.8 years (SD 10.82) and gender ratio of 59.3% women and 40.7% men. Of them, 232 patients (45.2%) completed the follow-up, 104 (42.9%) in the IG and 128 (47.2%) in the CG. Main outcome: In the intention-to-treat analysis, the biochemically-validated abstinence rate at 6 months was higher in the IG with 26.03% (63/242) versus 18.82% (51/271) in the CG (odds ratio (OR)=1.52, 95% CI: 1.00–2.31, P=.05). After adjusting for basal CO-oxymetry and bupropion intake, no substantial changes were observed (OR=1.52, 95% CI 0.99–2.33 P= .053; pseudo R2=0.045). In the IG, 61.16% (148/242) of users accessed the chatbot, average bot-patient interaction time was 121 minutes (CI 95% 121.1–140.0), and average number of contacts was 45.56 (SD 36.32).

Conclusions:
A treatment including a chatbot for helping in tobacco cessation was more effective than usual clinical practice in primary care.