[Clinical usefulness of visual analog scale for assessment of dyspnea at rest in patients with chronic respiratory diseases].

To evaluate the validity and clinical usefulness of the visual analog scale (VAS) for the measurement of dyspnea at rest, we employed the 150 mm VAS in 29 chronic respiratory disease patients who were clinically stable, and repeated the measurement 4 weeks and 8 weeks later for the evaluation of reproducibility. For the 8-week period, the individual medical treatments remained generally unchanged in all patients. Two patients were excluded from the study due to infection and pneumothorax. Dyspnea at rest was detected on VAS in 23 patients at the first measurement. The VAS measurement was 23.9 +/- 28.4 (mean +/- SD) mm at the first time, 22.0 +/- 23.1 mm at the 4th week, and 22.4 +/- 26.0 mm at the 8th week. There was no significant change among the three measurements. Twenty among the 23 patients with VAS indicative of dyspnea at rest were categorized into grades 4 and 5 of the Fletcher dyspnea category. However, the intensity of dyspnea was distributed widely within each Fletcher category. These results lead to the conclusion that VAS shows good reproducibility over a period of as long as 8 weeks and that VAS measurements can reveal patient-to-patient individual differences in dyspnea intensity which cannot be detected by the Fletcher dyspnea category. We propose that measuring dyspnea at rest using VAS is a useful method to obtain a valid clinical parameter.