Pragmatic randomized clinical trial, single-blind, with allocation 2:1 [Intervention Group (IG) and control group (CG)] in 5 acute hospitals. The IG will receive telephone assistance to quit smoking (including psychological and psycho-educational support and pharmacological treatment advice, if required) proactively for 12 months, and the CG only brief counselling after discharge.

To assess the effectiveness of a multicomponent and motivational intensive telephone-based intervention to stop smoking ("quit line") addressed to smokers with mental disorders discharged from hospitals.

Background: People suffering from mental illness are more likely to smoke. In Spain, up to 75% of patients hospitalized for mental disorders smoke, tripling the general population consumption. Life expectancy for people with severe mental illnesses is decreased by up to 25 years in comparison to the general population, mainly due to diseases caused or worsened by smoking. Hospitalized patients without monitoring after discharge quickly restore their tobacco use to previous levels. This evidence suggests the need of an appropriate follow-up intervention to prevent relapse after discharge and achieve higher rates of withdrawal in this population.

Objectives: To assess the effectiveness of a multicomponent and motivational intensive telephone-based intervention to stop smoking ("quit line") addressed to smokers with mental disorders discharged from hospitals.

Methods: Pragmatic randomized clinical trial, single-blind, with allocation 2:1 [Intervention Group (IG) and control group (CG)] in 5 acute hospitals. The IG will receive telephone assistance to quit smoking (including psychological and psycho-educational support and pharmacological treatment advice, if required) proactively for 12 months, and the CG only brief counselling after discharge. The sample size, calculated with an expected difference of 15 points on withdrawal between groups, α=0.05 and β=0.10 and 20% loss, will be of 334 (IG) and 176 (CG), which will be doubled to allow stratified analyses. Variables: a) dependent variables: self-reported smoking abstinence and verified by expired carbon monoxide levels, quit attempts, time of abstinence, motivation and self-efficacy to quit, and b) independent variables: age, sex and main disorder. Data analysis: multivariate logistic regression (odds ratio and confidence interval, CI 95%) of abstinence and other variables adjusted for potential confounding variables. Number of smokers needed to treat (NNT, and its 95% CI) to achieve one abstinent will be calculated.

Hypothesis: Abstinence rate (≥ 15%) of enrolled patients between groups. If the intervention is effective, the pragmatic nature of the study will permit to transfer it to the routine clinical practice with a reasonable investment.

Inclusion Criteria:

1. smokers;
2. adults of both sexes ≥ 18 years to ≤76 years of age;
3. that have stayed in an Acute or Detoxification mental health unit for more than 24 hours;
4. with a telephone, fixed or mobile;
5. residents in the metropolitan area of Barcelona;
6. that provide their informed consent.

Exclusion Criteria:

1. patient discharged from the psychiatric emergency room;
2. with dementia or brain damage;
3. that do not speak Spanish or Catalan;
4. pregnant women;
5. with hearing and/or speech deficit;
6. with insufficient reading comprehension skills in Spanish or Catalan;
7. that are trying to quit in smoking in another centre, or using another intervention in that moment;
8. that have voluntarily requested discharge;
9. that plan to shift their domicile outside of Barcelona county.

Individual data will not be shared with other researchers

Participants and hospital clinicians will be blind