Measuring Restrictive Lung Disease Severity Using FEV₁ vs TLC

No clear parameters currently exist to grade severity in restrictive lung disease as for other ventilatory diseases. This article evaluates whether total lung capacity (TLC) or forced expiratory volume in 1 second (FEV₁) better correlates with the symptomatology of patients with restrictive lung disease.

A retrospective review of 6461 patient records at Veterans Affairs Caribbean Healthcare System in Puerto Rico was conducted, and 414 patients met the inclusion criteria. Pulmonary function test, Modified Medical Research Council Dyspnea Scale, FEV₁, and TLC data were collected for each patient.

We identified a stronger correlation between FEV₁ (r = 0.25, P < .001) vs TLC (r = 0.15, P < .001) when related to the degree of dyspnea as measured with the Modified Medical Research Council Dyspnea Scale.

Results of this study suggest that compared with TLC, FEV₁ may provide a more accurate measure of restrictive lung disease severity. Further research should look for more accurate measures of patient dyspnea in restrictive lung disease.