Which is better among FEV1/FVC and FEV1/SVC in obstructive airway disease?

Saravanan M., P. M. Ramesh, K. Rajarajeswari


Background: Forced expiratory volume in 1 second (FEV1) to forced vital capacity ratio (FVC) is being used to diagnose the obstructive lung diseases. Forced manoeuvre (FVC) or relaxed/slow manoeuvre (SVC) can be used to determine vital capacity (VC). In healthy individuals the difference between SVC and FVC (SVC-FVC) is minimal whereas in the presence of airway obstruction this difference will become significant. The present study was done with the objective to detect and compare the airway obstruction by determining the FEV1/FVC and FEV1/ SVC ratios.

Methods: This was a prospective cross-sectional study done at OPD, Government Thiruvoteeswarar hospital of thoracic medicine/Kilpauk medical college during the period from September 2016 to February 2017among the patients presenting with symptoms of obstructive airway disease. The sample comprised of 353 patients who underwent spirometry according to standard of ATS/ERS guidelines. As per the criteria, the patients are classified into four groups, by spirometry.

Results: The analysis of FEV1/FVC revealed the presence of airway obstruction in 131 (37%) individuals compared to 165 (46%) individuals by the analysis of Fev1/SVC ratio. In the obstruction and mixed groups, the difference in vital capacity SVC – FVC is statistically superior (p<0.05) when compared to normal and restriction groups.

Conclusions: The FEV1/SVC ratio detected the presence of airway obstruction in more individuals than did FEV1/FVC ratio and hence FEV1/SVC considered as more reliable factor in the detection of obstructive airway diseases.


FEV1/FVC, FEV1/SVC, Obstructive air way disease, SVC-FVC

Full Text:



Swanney MP, Ruppel G, Enright PL, Pedersen OF, Crapo RO, Miller MR, et al. Using the lower limit of normal for the FEV1/FVC ratio reduces the misclassification of airway obstruction. Thorax. 2008;63(12):1046-51.

Sahebjami H, Gartside PS. Pulmonary function in obese subjects with a normal FEV1/FVC ratio. Chest. 1996;110(6):1425-9.

Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care (partial update). Available at: Accessed on 10 February 2016.

Chan ED, Irvin CG. The detection of collapsible airways contributing to airflow limitation. Chest. 1995;107(3):856–9.

Constán EG, Medina JP, Silvestre AH, Alvarez II, Olivas RB. Difference between the slow vital capacity and forced vital capacity: predictor of hyperinflation in patients with airflow obstruction. Internet J Pulmonary Med. 2005;4(2):1-1.

Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi R, et al. Interpretative strategies for lung function tests. Eur Res J. 2005;26(5):948-68.

Barros AR, Pires MB, Raposo NM. Importance of slow vital capacity in the detection of airway obstruction. J Bras Pneumol. 2013;39(3):317-22.

Rasheed A, Vasudevan V, Shahzad S, Arjomand DM, Reminick S. Underdiagnosis of obstructive disease by spirometry. Chest. 2011;140(4):691.