Do GOLD stages of COPD severity really correspond to differences in health status?

The purpose of this study was to assess whether different stages of
chronic obstructive pulmonary disease (COPD) severity defined according to the Global
Initiative for Chronic Obstructive Lung Disease (GOLD) criteria correlate with
meaningful differences in health status.
A total of 381 COPD patients, aged 73¡6 yrs, were classified in the five GOLD
stages. Disease-specific (St George Respiratory Questionnaire (SGRQ)) and generic
indexes of health status were measured in all patients. Multivariate analysis of
covariance or Kruskal Wallis tests were used to compare health status indexes across
the spectrum of GOLD stages of COPD severity.
GOLD stages of COPD severity significantly differed in SGRQ components and
Barthel9s index, but not in the indexes assessing cognitive and affective status and
quality of sleep. The largest variation in health status was observed at the transition
from stage IIa to stage IIb, while there were no other significant differences between
consecutive stages. Both female sex and comorbidity were associated with a greater
impact of COPD on the health status.
In conclusion, the upper limit of stage IIb (forced expiratory volume in one second of
49%) marks a threshold for dramatic worsening of health status. Progression of chronic
obstructive pulmonary disease severity from stage 0 to stage IIa does not correspond to
any meaningful difference in health status.