Abstract / Summary
Background: Prolonged Forced Expiratory Time (FET) is a simple, non-invasive measure that may serve as a useful indicator of airway obstruction. However, its optimal threshold for detecting obstruction remains unclear. This study aimed to investigate the relationship between FET and spirometric obstructive patterns and determine the optimal FET cut-off point for predicting airway obstruction in asthmatic patients. Methods: A cross-sectional study was conducted among 428 adult asthmatic patients attending the outpatient clinic in Khartoum, Sudan. Spirometry was performed following ATS/ERS guidelines to classify participants into obstructive and non-obstructive patterns based on an FEV1/FVC ratio <70%. The diagnostic value of FET in assessing airway obstruction was investigated using sensitivity, specificity, PPV, and NPV at cut-off points of 4, 4.5, 5, 5.5, 6, 6.5, and 7 seconds. Receiver Operating Characteristic (ROC) curve analysis was conducted to assess the discriminatory ability of FET, and the Youden Index was used to determine the optimal cut-off. Correlation analyses were used to explore associations between FET and lung function parameters. Results: Prolonged FET was significantly associated with obstructive spirometry patterns (p < 0.001). The 6-second cut-off demonstrated an optimal balance, with a sensitivity of 100%, specificity of 34%, and positive and negative predictive values of 38% and 100%, respectively. FET showed a significant negative correlation with FEV1/FVC ratio (p < 0.001) and a positive correlation with FVC (p < 0.001). Conclusion: Prolonged FET is a simple, non-invasive indicator of airway obstruction with acceptable diagnostic value. The 6-second FET, with its high sensitivity and specificity, might be helpful as a preliminary screening tool for airway obstruction. Further research is needed to explore the role of FET in monitoring airway diseases.