Background: Medical Research Council (MRC) chronic dyspnea scale, used for the estimation of disability due to dyspnea, may serve as a simple index of disease severity and extent in patients with idiopathic pulmonary fibrosis (IPF). However, its relationship with other commonly used measures has not been evaluated.
Methods: The association of MRC chronic dyspnea scale with lung function indices and high-resolution computerized tomography (HRCT) scores such as the total interstitial disease score (TIDs) and the fibrosis score (Fs) was examined in 26 untreated patients with IPF sequentially recruited over a period of 3 years. The aim of this observational study was to explore the relationship between dyspnea, impairment of lung function and CT estimation of disease severity in patients with IPF.
Results: The MRC dyspnea score was significantly associated with FVC, FEV1, TLC, DLCO, PaO2, and PaCO2 and with both HRCT scores. In multiple regression analysis only the FVC (OR = 0.85, 95% CI = 0.75-0.95, P = 0.004) and PaCO2 (OR = 0.69, 95% CI = 0.50-0.95, P = 0.02) correlated with dyspnea. Furthermore, both TIDs and Fs were negatively associated with FVC, FEV1, TLC and PaO2. In multiple regression analysis only the FVC correlated with both TIDs (r2 = 0.57, P = 0.0001) and Fs (r2 = 0.46, P = 0.0005).
Conclusions: These observations suggest that the MRC dyspnea scale could offer useful information about the estimation of severity in patients with IPF. Furthermore among functional indices the FVC seems to be the best estimator of disease severity and extent.