Evaluation of smoking cessation after interventions within the ‘INSPIRE: respiratory health’ program: a longitudinal observational study

Despite the availability of pharmacological and psychosocial interventions within the Brazilian Unified Health System (Sistema Único de Saúde - SUS), smoking cessation rates in real-world public healthcare settings remain limited, particularly among socioeconomically vulnerable populations. Evaluating the effectiveness of structured programs in specialized public services is essential to inform evidence-based tobacco control policies. This study aimed to evaluate the one-year smoking cessation rate in the “INSPIRE: Respiratory Health” Program and to identify independent predictors of therapeutic success. A longitudinal observational study with a 12-month follow-up was conducted at the “INSPIRE: Respiratory Health” Program, affiliated with the Botucatu Medical School (FMB/UNESP) and the Clinical Hospital of Botucatu (HCFMB), São Paulo, Brazil. Of the 414 individuals initially screened, 174 completed the follow-up and were included in the analysis. Sociodemographic characteristics, smoking history, and adherence to pharmacological therapy were assessed. Data analysis included group comparison tests and binary logistic regression to identify factors associated with cessation. The smoking cessation rate was 23.6% (41/174) among study completers. In a conservative intent-to-treat (ITT) sensitivity analysis assuming all non-respondents continued smoking, the overall cessation rate was 9.9% (41/414). No significant differences were observed between quitters and non-quitters regarding sex, age, or socioeconomic status. In exploratory analyses, individuals who successfully quit presented lower baseline BMI and higher cumulative smoking pack-years; however, in the logistic regression model, only adherence to pharmacological therapy was an independent predictor of abstinence (aOR = 10.843; 95% CI: 3.854–30.510; p < 0.001). The “INSPIRE: Respiratory Health” Program achieved a cessation rate consistent with those reported for specialized services. Adherence to pharmacological treatment was strongly associated with therapeutic success. In contrast, structural barriers—such as cost and medication shortages—limited adherence and may have compromised overall cessation rates. These findings underscore the importance of ensuring continuous access to interventions within the public health system and providing longitudinal support for smokers.