Long-term changes in dyspnea, lung function, and exercise capacity in COPD patients

To examine longitudinal changes in dyspnea, lung function, and exercise capacity in COPD patients and to compare baseline data of frequent and infrequent exacerbators at trial entry.

Nineteen stable COPD patients without significant co-morbidity (age, 58.4 +/- 8.4 years; FEV1% = 33 +/- 12%; mean +/- SD) participated in the study. After a mean period of 36 months (range = 24 - 49) the patients were retested using an identical protocol.

Repeated measures analysis showed that there was significant deterioration of FEV1 L (from 1.028 +/- 0.349 to 0.928 +/- 0.307; p = 0.007), PImax cm H2O (from 61.9 +/- 24.2 to 42.0 +/- 22.1; p = 0.007), PaO2 mm Hg (from 69.0 +/- 8.6 to 60.1 +/- 6.8; p = 0.003), PaCO2 mm Hg (from 43.1 +/- 4.9 to 47.3 +/- 4.5; p = 0.001), ATS (from 2.4 +/- 1.0 to 2.8 +/- 0.8; p = 0.031), and 6MWD m (from 389 +/- 130 to 341 +/- 135; p = 0.014). There were also changes in IC, T(L,CO)/V(A), PAP and Borg, but they were not statistically significant. Differentiation of patients by frequency of exacerbations per year of observation (> 2 < or =) discriminated them with respect to functional parameters (FEV1, FVC, IC), dyspneic indices (ATS, VAS and Borg) and exercise capacity (6MWD) at the time of enrollment.

1) Lung function parameters, blood-gas and dyspneic indices, and exercise capacity decline over a mean period of 36 month in patients with COPD; 2) Patients with frequent exacerbations experience more dyspnea and have lower levels of lung function and exercise capacity at trial entry.