FEF50/0.5FVC versus FEV1/FVC: which ratio correlates better with physical activity in chronic respiratory diseases?

<bold>Introduction:</bold> Chronic respiratory diseases often entail obstructive airway limitations, impacting patients' physical activity. Assessment of airflow obstruction involves the FEV1/FVC and the FEF50/0.5 FVC ratios. This study aimed to compare the correlation levels between these ratios and the Physical Activity Index (Ricci) in patients afflicted with chronic respiratory diseases. <bold>Methods:</bold> This was a cross-sectional study including 88 patients who had been referred to Pulmonary Function Testing Department at Abderrahmane Mami Hospital, Ariana. All patients underwent spirometry with measurement of FEV1, FVC, FEV1/FVC ratio, and FEF50/0.5 FVC ratio. Additionally, patients completed the "RICCI & Gagnon" questionnaire to assess physical activity and modified Medical Research Council Scale (mMRC) to evaluate dyspnea. <bold>Results:</bold> The mean age was 50.01±14.80 years with a female predominance (59.1%). Among the study population, 51(58%) had asthma, 23(26,1%) had COPD and 14 (15,9%) had interstitial lung disease. The mean "RICCI & Gagnon" score was 17.34±7.97 and the mean mMRC score was 1.15±0.87. Mean values for the FEV1/FVC ratio and FEF50/0.5 FVC ratio were 0.724±0.106 and 1.61±0.713, respectively. Furthermore, the "RICCI & Gagnon" score was significantly correlated with FEF50/0.5 FVC ratio (r=-0.39; p=0.018) and mMRC score (r=-0.24; p=0.027) but not with FEV1/FVC ratio. <bold>Conclusion:</bold> Our study demonstrated that FEF50/0.5 FVC ratio can be used as a marker of physical activity limitation in patients with chronic respiratory diseases.