Association Found Between Walking Test Performance and Patient-Reported Outcomes in COPD

Among the many exercise tests used to assess patients with chronic obstructive pulmonary disease (COPD), a 6-minute walking test was most strongly associated with patient-reported outcomes and quality of life.

A recent article published in the International Journal of Chronic Obstructive Pulmonary Disease noted that while exercise tests like walking or shuttle tests are reliable ways to measure a patient’s capacity for exercise, prior research has not explored whether they reflect health-related quality of life (HRQoL) as perceived by the patient. The study authors performed a systematic review of 28 articles to examine this potential association more closely.

Some of the studies assessed the link between various exercise tests and the St. George’s Respiratory Questionnaire (SGRQ), a commonly-used tool that measures self-reported health status and HRQoL, while others looked at tests assessing self-reported breathlessness. The most commonly used exercise tests were the 6-minute walk test, 12-minute walk test, incremental and endurance shuttle walk tests, incremental and endurance cycle ergometer tests, and treadmill tests.

The researchers found that the strongest association was between 6-minute walk test and the total score on the SGRQ. Specifically, as the distance walked increased, the questionnaire scores decreased, indicating better health status and HRQoL. This association was also present between the 6-minute walk test and the baseline dyspnea index, which measures self-reported breathlessness.

One theme observed during the literature review was that the body of evidence in this field was sparse. For instance, there were no studies found that linked performance on certain exercise tests, namely the 12-minute walk test or the endurance shuttle walk test, to scores on all subscales of the SGRQ. There were also inconsistent results found across studies for the tests that had been examined.

“Recent guidelines on the diagnosis and treatment of COPD indicate that the assessment of disease severity is improved by using functional criteria, such as exercise capacity,” the review authors wrote. “However, the current evidence suggests that no single exercise test accurately reflects HRQoL or breathlessness in patients with COPD.”

They concluded that clinicians should not rely solely on exercise tests or patient-reported outcomes to predict COPD-related hospitalizations or prognosis. Instead, a more complete assessment should incorporate these factors and others. They mentioned the BODE index, which measures body mass index, airflow obstruction, dyspnea, and exercise capacity, as a useful tool for measuring COPD severity and prognosis.