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 impact on daily function in chronic airflow limitation (CAL) is crucial but methods are not standardized.
• Existing measures for dyspnea and functional status in CAL patients require validation in clinical trials.

Purpose of the Study:

• To compare the performance of the Six Minute Walk test, post-walk dyspnea rating, and three questionnaires in assessing treatment effects in CAL.
• To identify the most responsive and valid measure of functional status for clinical trials in chronic lung disease.

Main Methods:

• A controlled trial involving 24 patients with fixed CAL evaluated inhaled salbutamol and oral theophylline.
• Assessed functional status using the Six Minute Walk test, post-walk dyspnea rating, Chronic Respiratory Questionnaire (CRQ), Oxygen Cost Diagram, and modified MRC Dyspnea Questionnaire.

Main Results:

• Salbutamol and theophylline showed statistically significant improvements in daily dyspnea across all measures.
• The CRQ demonstrated greater responsiveness and validity compared to the Oxygen Cost Diagram and MRC Dyspnea Questionnaire.
• CRQ dyspnea score changes correlated strongly with spirometry, walk test performance, and global dyspnea ratings.

Conclusions:

• The Chronic Respiratory Questionnaire (CRQ) is a responsive and valid tool for assessing functional status in chronic lung disease clinical trials.
• When using the Six Minute Walk test as an outcome measure, including a post-walk dyspnea rating is recommended for comprehensive assessment.