Functional status measurement in COPD: a review of available methods and their feasibility in primary care

Guidelines advocate that improvement in functional status should be a major goal in COPD treatment. Many tools are available to assess aspects of functional status. This review aims to categorize systematically the available tools based on their construct (i.e. what the tool intends to measure) and to rate the tools for use in the primary care setting.

PubMed was searched with the keywords 'functional status' or 'physical capacity' or 'functional capacity' and 'COPD'. All tools were categorised and rated on their measurement properties, feasibility, and usage in primary care COPD patients. The tools were divided into four constructs - functional capacity, functional performance, functional reserve, and capacity utilisation - and used the following modes of measurement: laboratory tests; semi-laboratory tests; field tests; and patient-reported outcomes.

The PubMed search resulted in 364 articles. Thirty-two tools were identified and rated.

In primary care, the 6-minute walking distance test is the most reliable semi-laboratory functional capacity test, but is not very practical. The pedometer is the best functional performance field test. The Medical Research Council (MRC) dyspnoea questionnaire and the functional status domain of the Clinical COPD Questionnaire (CCQ) are the best patient-reported outcome tools to assess functional performance.