[Validation of a visual analog scale to measure dyspnea in patients with diffuse interstitial lung disease]

In order to validate a form of measuring dyspnea, a visual analog scale (VAS) was applied to 27 patients with different types of interstitial lung diseases (ILD). The test was done in two days with an interval of one month (dyspnea1 and dyspnea2). Additionally, the forced vital capacity (FVC) was obtained on these occasions (FVC1, FVC2). Nineteen patients with a recent diagnosis of ILD (RD) and eight with a previous diagnosis of ILD (PD) were included. In patients with RD, dyspnea1 correlated with FVC1 (r = -0.66, p < 0.01). A month after the initial treatment with steroids, dyspnea (mean +/- SD) decreased from 38 +/- 25 mm to 17 +/- 19 mm (p < 0.03), while the FVC increased from 1086 +/- 464 mL to 1350 +/- 536 mL (p < 0.05). Likewise, dyspnea2 correlated with FVC2 (r = -0.47, p < 0.05). As expected, patients with PD did not exhibit significant changes in the analysis of dyspnea on the second evaluation. The inter-observer coefficient of variation for the 8 patients with PD was of 5% and 9% for the first and second evaluations respectively, while the intraclass correlation coefficient was 0.92 and 0.91 respectively. The intra-observer coefficient of variation of two different observers was of 15% and 16% respectively, while the intraclass correlation coefficient was 0.69 and 0.62 respectively. These results suggest that the use of a VAS might be useful for the initial evaluation and during the follow-up of patients with ILD.