Abstract Rationale Cystic Fibrosis (CF) is a chronic, multisystemic genetic disease whose clinical severity is strongly associated with the progressive decline of pulmonary function. Identifying predictors of this decline is crucial for improving disease management, guiding therapeutic interventions, and informing public health policies, especially in low- and middle-income regions. Despite significant advances in CF care, data on the determinants of pulmonary function severity in individuals from Northeastern Brazil remain scarce. This study aimed to identify independent predictors associated with pulmonary function severity in children, adolescents, and adults with CF assisted in public health services in João Pessoa, Brazil. Methods A cross-sectional, descriptive study was conducted including individuals with confirmed CF diagnosis, aged 4-27 years, receiving care through the public health network. Pulmonary function was evaluated using spirometry according to international standards, considering forced expiratory volume in one second (FEV1), forced vital capacity (FVC), vital capacity (VC), forced expiratory flow at 25-75% of FVC (FEF25–75%), and the Tiffeneau index. In addition to lung function, body composition was assessed by bioelectrical impedance, and sociodemographic variables such as sex, family income, and educational level were analyzed. Multiple linear regression analysis was performed to identify independent predictors of pulmonary function severity, adopting a 5% significance level. Results Nineteen individuals of both sexes participated, with a mean age of 14.1 ± 6.7 years (range 4-27). Genetic testing was available for 84.2% of the sample, of whom 57.9% presented the F508del mutation, the most prevalent genotype among people with CF. The sample was predominantly composed of White and mixed-race participants, with low socioeconomic status and limited educational attainment. Lifetime hospitalizations were reported by 96.7% of participants, and 57.9% were exclusively assisted by the Brazilian Unified Health System (SUS). Spirometric evaluation showed that 31.6% of individuals had FEV1 values below 40% of predicted, indicating severe respiratory impairment. Multiple linear regression analysis identified family income and male sex as independent predictors of variation in the Tiffeneau index (p = .0001; R² = .51). Additionally, body mass index (BMI) was identified as an independent predictor for FEV1 (p = .001; R² = .53), FVC (p .0001; R² = .57), and FEF25–75 (p = .002; R² = .40). Conclusions Clinical, anthropometric, and socioeconomic factors significantly influenced pulmonary function severity in individuals with CF in Northeastern Brazil. These findings reinforce the need for comprehensive, multidisciplinary care strategies that integrate biological, nutritional, and social aspects to improve disease outcomes and reduce health disparities among people with Cystic Fibrosis in low-resource regions. This abstract is funded by: This study was funded by the National Council for Scientific and Technological Development (CNPq) and financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance code 001
Souza et al. (Fri,) studied this question.