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UNRAVELING THE SEVERITY OF OBSTRUCTIVE
VENTILATORY IMPAIRMENT : INVESTIGATING FEV1/FVC
RATIO AS A POTENTIAL GRADING TOOL
SABA BOUBAKRI1, BALSAM BARKOUS1,2, CHAIMA BRIKI1, WIÈME BEN HMID1,
SONIA ROUATBI1,2, HELMI BEN SAAD1,2,3
1DEPARTMENT OF PHYSIOLOGY AND FUNCTIONAL EXPLORATIONS, FARHAT HACHED
HOSPITAL, SOUSSE, TUNISIA. 2RESEARCH LABORATORY OF HEART FAILURE (LR12SP09),
FARHAT HACHED HOSPITAL, SOUSSE, TUNISIA. 3INTERNATIONAL CENTER OF FUNCTIONAL
EXPLORATIONS, SOUSSE, TUNISIA.
INTRODUCTION. While the FEV1/FVC z-score is commonly used to confirm the
diagnosis of obstructive ventilatory impairment (OVI), the FEV1 z-score is crucial for
assessing its severity. However, the potential of using the FEV1/FVC ratio for
grading OVI remains unexplored.
AIMS. To i) compare the severity levels of OVI using FEV1 vs. FEV1/FVC z-scores,
and ii) evaluate the correlation between FEV1 and FEV1/FVC z-scores and lung
hyperinflation (LH).
METHODS. This was a retrospective comparative study involving male smokers
with more than 10 pack-years who underwent plethysmography following ERS-
ATS technical standards. The study applied the ERS-ATS recommended definition
(ie; FEV1/FVC z-score <-1.65) and severity grading (ie; unclassified (z-score >-1.65),
mild (z-score: -1.65 to -2.50), moderate (z-score: -2.50 to -4.00), and severe (z-score
≤ -4.00)). LH was assessed using the residual volume/total lung capacity (RV/TLC).
Correlation coefficients (r) between RV/TLC and FEV1 or FEV1/FVC z-scores were
calculated.
RESULTS. Seventy-one male patients with OVI (mean age: 63±10 years) were
included. i) There were no significant differences (p=0.116) in the frequencies of OVI
severity grades assessed using FEV1 vs. FEV1/FVC z-scores: Unclassified (0.0 vs.
5.6%), mild (21.1 vs. 32.4%), moderate (56.3 vs. 53.5%), and severe (16.9% vs. 14.1%). ii)
RV/TLC z-score was significantly correlated with FEV1 (r= -0.653) and FEV1/FVC
(r= -0.417) z-scores, showing comparable strength (p=0.052 between both “r”).
CONCLUSION. Both FEV1 and FEV1/FVC ratios are comparable in grading OVI and
demonstrate significant correlations with LH marker.
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