Prevalence of Cystic Fibrosis and Pattern of Lung Function Impairment in Adults Presenting With Bronchiectasis at a Tertiary Care Hospital in Resource Poor Country Bangladesh: A Cross‐Sectional Study

ABSTRACT Background and Aims Bronchiectasis is a common but neglected respiratory condition, particularly in resource‐poor countries such as Bangladesh. Cystic fibrosis (CF), a recognized cause of bronchiectasis in children, especially among Caucasians, is increasingly reported in adults of Asian descent. However, CF remains under‐recognized in Bangladesh, and no prior data exist on its prevalence in adults. This study aimed to determine the prevalence of CF in adult bronchiectasis patients and to assess their lung function characteristics using spirometry in Bangladesh. Methods This cross‐sectional study was conducted in the Department of Respiratory Medicine at Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, from June 2023 to November 2024. A total of 130 adults with bronchiectasis were enrolled in accordance with the inclusion and exclusion criteria. CF diagnosis was established using pilocarpine iontophoresis sweat chloride testing, and lung function severity was assessed by spirometry. Statistical analyses were performed using SPSS version 25. Results Among 130 participants, 12 were diagnosed with CF, representing 9.2% of patients. Obstructive airway abnormality was the predominant pattern among CF patients (75.0%), with half presenting in the mild category. A moderate negative correlation was observed between forced expiratory volume in 1 s (FEV 1 % predicted) and sweat chloride concentration (Cl − ) (Spearman's rho = *−0.477, p = 0.117). Conclusion Approximately one in ten adult bronchiectasis patients in Bangladesh were found to have CF, and most had mild airway obstruction. These findings highlight that CF, traditionally regarded as a childhood disease, should also be considered in adult bronchiectasis, particularly in South Asian populations where it remains underdiagnosed.