Measuring functional status in chronic lung disease: conclusions from a randomized control trial.

Area of Science:

• Pulmonary Medicine
• Clinical Trials
• Respiratory Health

Background:

• Assessing treatment efficacy in chronic airflow limitation (CAL) requires validated functional measures.
• Current methods for evaluating daily functional impact in CAL patients are not definitively established.

Purpose of the Study:

• To compare the performance of the 6-minute walk test, post-walk dyspnea ratings, and three dyspnea questionnaires in patients with CAL.
• To determine the most responsive and valid measure for assessing functional status in clinical trials for chronic lung disease.

Main Methods:

• A controlled trial involving 24 patients with fixed chronic airflow limitation.
• Evaluated inhaled salbutamol and oral theophylline treatments.
• Compared the 6-minute walk test, post-walk dyspnea rating, Oxygen Cost Diagram, Medical Research Council Dyspnea Questionnaire, and the Chronic Respiratory Questionnaire (CRQ).

Main Results:

• All tested measures detected clinically significant effects of salbutamol and theophylline on daily dyspnea.
• The Chronic Respiratory Questionnaire (CRQ) demonstrated greater power than the Oxygen Cost Diagram and the modified Medical Research Council Dyspnea Questionnaire.
• CRQ dyspnea score changes correlated more strongly with spirometry, walk test performance, and global dyspnea ratings.

Conclusions:

• The Chronic Respiratory Questionnaire (CRQ) is a responsive and valid tool for measuring functional status in clinical trials for chronic lung disease.
• CRQ is recommended for assessing treatment effects on daily activities in patients with chronic airflow limitation.
• This study provides evidence for the superior performance of CRQ in capturing treatment-related functional improvements.