Background:
In Brazil, the treatment of tobacco dependence is available at no cost. This study aimed to identify factors associated with attempting to quit and of successful smoking cessation in a population-based sample of Brazilian smokers.

Methods:
Data came from the first two waves of the International Tobacco Control (ITC) Brazil Survey, conducted in 2009 and 2012/2013 in three cities: Rio de Janeiro, São Paulo, and Porto Alegre. Prospective cohort data were collected from 488 adults (≥18 years) who smoked at Wave 1 who were resurveyed at Wave 2. Crude and adjusted relative risks (RR) for two outcomes (making a quit attempt between Wave 1 and Wave 2 and successfully quitting by Wave 2) were estimated. Multivariable multilevel logistic regression models were used, whereby variables were added to the models in a series of blocks.

Results:
Nearly two-thirds (65.6%) of smokers attempted to quit between waves, and 23.4% had quit at Wave 2. Intention to quit smoking at Wave 1 was the only variable associated with attempt to quit by Wave 2 (OR=2.85; 95%CI 1.64-4.94; p< 0.001). Smokers of higher socioeconomic status (OR_{high versus low}=1.80; 95%CI 1.05-3.10; p=0.03) and lower nicotine dependence (OR_{low HSI versus high HSI}=1.94; 95%CI 1.10-3.43; p=0.02) were more likely to successfully quit. The presence of another adult smoker at home was negatively related to successful quitting (OR=0.50; 95%CI 0.26-0.94; p= 0.03).

Conclusions:
These results are generally consistent with prior research and have potential to inform governmental interventions to promote tobacco cessation, particularly among disadvantaged groups.