Study objectives: To compare categorizations of the
level of dyspnea with the staging of disease severity as defined by the
FEV1 in representing how the health-related quality of life
(HRQOL) is distributed in patients with COPD.
Setting: Outpatient clinic at
the respiratory department of a university hospital.
Patients: A total of 194 consecutive male patients with
stable, mild-to-severe COPD.
Measurements: The score
distributions for the components of the St. George’s respiratory
questionnaire (SGRQ) were used as disease-specific HRQOL measures, and
the scores from the Medical Outcomes Study Short Form 36-item
questionnaire (SF-36) were used as generic HRQOL measures. These scores
were stratified according to the level of dyspnea, as defined by the
Medical Research Council (MRC) dyspnea scale, and the stage of disease
severity, as defined by the American Thoracic Society (ATS).
Differences in the HRQOL scores among the subgroups were compared by an
analysis of variance (ANOVA). Multiple pairwise comparisons were made
with Fisher’s least significant difference (LSD) method, with the
overall α-level set at 0.05.
Results: In those
groups classified according to the level of dyspnea, significant
differences were observed for the scores on the SGRQ and SF-36 (ANOVA,
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
on the SF-36, were significantly worse for patients with severe dyspnea
(MRC scale grades, 3, 4, and 5, respectively) than for those
with moderate dyspnea (MRC grade level, 2; Fisher’s LSD method,
p < 0.05). Significant differences were 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 statistically
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 staging. In addition to the ATS
disease staging, categorizations based on the level of dyspnea may be
useful to clinicians in terms of the HRQOL of COPD