A comparison of the level of dyspnea vs disease severity in indicating thehealth-related quality of life of patients with COPD

Study objectives: To compare categorizations of the level of dyspnea with t he staging of disease severity as defined by the FEV1 in representing how t he health-related quality of life (HRQOL) is distributed in patients with C OPD, Design: Cross-sectional study. Setting: Outpatient clinic at the respiratory department of a university ho spital, Patients: A total of 194 consecutive male patients with stable, mild-to-sev ere COPD. Measurements: The score distributions for the components of the St. George' s respiratory questionnaire (SGRQ) were used as disease-specific HRQOL meas ures, and the scores from the Medical Outcomes Study Short Form 36-item que stionnaire (SF-36) were used as genetic HRQOL measures. These scores were s tratified according to the level of dyspnea, as defined by the Medical Rese arch Council (MRC) dyspnea scale, and the stage of disease severity, as def ined by the American Thoracic Society (ATS). Differences in the HRQOL score s among the subgroups were compared by an analysis of variance (ANOVA). Mul tiple pairwise comparisons were made with Fisher's least significant differ ence (LSD) method, with the overall alpha-level set at 0.05, Results: In those groups classified according to the level of dyspnea, sign ificant differences were observed for the scores on the SGRQ and SF-36 (ANO VA, p < 0.05), The scores for activity and impact, and the total scores of the SGRQ and all scales, except for bodily pain and general health an the S F-36, were significantly worse for patients with severe dyspnea (MRC scale grades, 3, 4, and 5, respectively) than for those with moderate dyspnea (MR C grade level, 2; Fisher's LSD method, p < 0.05), Significant differences w ere recognized among the different stages of disease severity with respect to the scores from all scales of the SF-36, except for bodily pain, and all scores from the SGRQ (ANOVA, p < 0.05), However, differences in the scores on the SGRQ and SF-36 between patients with ATS stage II disease (FEV1, 35 to 49% predicted) and stage III disease (FEV1, < 35% predicted) were not s tatistically significant. Conclusions: Using the SGRQ and SF-36, the HRQOL of patients with COPD was more clearly separated by the level of dyspnea than by the ATS disease stag ing. In addition to the ATS disease staging, categorizations based on the l evel of dyspnea may be useful to clinicians in terms of the HRQOL of COPD p atients.