Patterns of Changes and Diagnostic Values of FEF50% , FEF25% - 75% and FEF50%/FEF25% - 75% Ratio in Patients with Varying Control of Bronchial Asthma

• Published in: International journal of health sciences Vol. 10; no. 1; pp. 3 - 11
• Main Author: Lutfi , Mohamed Faisal
• Format: Journal Article
• Language: English
• Published: Al Qasim - Saudi Arabia Qassim University 01.01.2016; Qassim University, Kingdom of Saudi Arabia
• Subjects: BRONCHIAL ASTHMA; DIAGNOSIS; IMMEDIATE HYPERSENSITIVITY; Original; PATIENTS; RESPIRATORY DISEASES; أمراض التنفس; التشخيص; الربو الشعبي; المرضى; فرط الحساسية الفوري; FEF50; Asthma control test; FEF25%–75; Bronchial Asthma; flow volume loop
• ISSN: 1658-3639; 1658-7774
• DOI: 10.12816/0031221

The pattern of change in FEF50%, FEF25%-75% and FEF50%/FEF25%-75% ratio depends on mechanics of forceful expiration, provided that non-homogenous lung emptying is faithfully recorded in the expiratory flow-volume loops. To assess the potential clinical value of FEF50%, FEF25%-75% and FEF50%/FEF25%-75% ratio as an indicator of bronchial asthma (BA) control. The study involved 75 patients with BA matched for age and gender with 45 non-asthmatic subjects. Based on asthma control test (ACT) and spirometry, asthmatic patients were subdivided into controlled and poorly controlled/uncontrolled. The relationship between FEF50% and FEF25%-75% as well as FEF50%/FEF25%-75% ratio and ACT score were assessed using linear regression. ROC curves were used to assess reliability of FEF25%-75% and FEF50% to diagnose BA in patients with different degree of asthma control. FEF50% correlated strongly with FEF25%-75% (r = 0.989, P < 0.001) and the relationship between the two indices is governed by the formula FEF50% = 1.132* FEF25%-75% - 0.003. There was no significant correlation (r = - 0.159, P = 0.083) between FEF50%/FEF25-75% ratio and ACT score. The diagnostic capability of FEF25%-75% for spirometric diagnosis of BA is only marginally better compared to FEF50% (area under ROC curves were 0.88 and 0.89 respectively, P < 0.001); however, diagnostic power of both spirometric indices deceased with poor BA control. FEF50%/FEF25%-75% has no clinical value as an indicator for BA control. Role of FEF25%-75% in evaluation of BA is marginally better than FEF50%; however, efficiency of both indices declined substantially as BA control worsened.