Objective: To analyze the correlation between quality of life and 1) lung function parameters at rest and during exercise, and 2) mean baseline dyspnea measured on two scales--Mahler's baseline dyspnea index (BDI/TDI) and the Medical Research Council (MRC) scale. We sought to observe the factor or factors having the greatest impact on the quality of life of such patients.
Material and methods: Fifty-five patients diagnosed of COPD in stable phase of disease participated. Al underwent lung function testing at rest and during exercise (shuttle walking test with increasing loads and an exercise cycle test). Quality of life was assessed on the validated Spanish translation of the Chronic Respiratory Disease Questionnaire, which refers specifically to COPD. Baseline dyspnea was measured using Mahler's BDI/TDI and the MRC scale.
Results: Mean patient age was 63 +/- 9.5 years and FEV1 was 40 +/- 16.9%. Overall quality of life and each sub-item correlated significantly with mean dyspnea on both scales (BDI/TDI and MRC). Effort was weakly correlated and function parameters at rest were unrelated. Multiple correlation analysis showed that baseline dyspnea (BDI/TDI) was the most important predictor of quality of life.
Conclusions: Dyspnea, particularly when expressed as BDI/TDI but also as measured on the MRC scale, correlates more highly with quality of life than does any other parameter. This indicates that dyspnea has greater impact than other factor on quality of life and that BDI/TDI provides a good baseline assessment of dyspnea in COPD patients.