Influence of clinical biomarkers and demographic characteristics on predicted FEF25–75 in Iraqi patients with Asthma

Objective: This study aimed to investigate the associations between predicted Forced Expiratory Flow at 25–75% of pulmonary volume (FEF25–75) and selected clinical biomarkers, namely serum periostin, peripheral blood eosinophil count, and immunoglobulin E (IgE) levels, in a cohort of Iraqi patients diagnosed with bronchial asthma. Given that FEF25–75 reflects small airway function and is considered a sensitive marker of early airway obstruction, this study sought to explore its potential correlation with established indicators of airway inflammation and allergic response. Methods: A cross-sectional analytical design was employed to assess the relationship between mid-expiratory lung function and inflammatory biomarkers among adult asthmatic patients. The study was conducted at a private respiratory clinic in Hillah, Iraq, and spanned a duration of one year. Patients were enrolled based on a clinical diagnosis of asthma according to Global Initiative for Asthma (GINA) guidelines, and spirometric measurements were obtained to assess lung function. Blood samples were collected for biomarker analysis using standard laboratory techniques. Results: The mean age of patients is 38.1, and the percentage of female patients is 54.8%. Patients with low predicted FEF25–75 (≤65%) had significantly higher levels of serum periostin (p=0.035), blood eosinophil counts (p=0.03), and IgE (p=0.05) compared to those with normal FEF25–75. There are no significant associations found with age, sex, or BMI. However, family history was associated. Conclusion: This supports the use of FEF25–75 alongside biomarker profiling for improved asthma phenotyping.