Assessing COPD Using PROs and Exercise Test Outcomes

The assessment of chronic obstructive pulmonary disease (COPD) now allows for the evaluation of various patient-reported outcomes (PROs); however, these PROs assess different disease features than exercise test outcomes. According to new research published in Health and Quality of Life Outcomes, individual PROs should still be supported by additional functional measurements.

The researchers assessed the association between different exercise test outcomes and PROs, such as health-related quality of life (HRQOL), mood status, level of care dependency, and dyspnea, in 518 patients with COPD before and after pulmonary rehabilitation (PR). Prior research has indicated “a very weak to moderate negative correlation” between the 6-minute walking distance (6MWD) and HRQOL, and there are contrasting results for the relationship between PROs for dyspnea and 6MWD.

“So, it still remains unclear whether and to what extent PROs mirror the exercise performance of patients with COPD,” the authors explained.

The mean baseline 6MWD for the 518 participants was 424 ± 124 minutes and one-fourth of the patients had a 6MWD below 350 minutes. According to the PROs, there was a high degree of dyspnea (80.7% had a modified Medical Research Council score of 2 or higher), anxiety and depression (34.8% and 33.4%, respectively, ≥10 points as measured by the Hospital Anxiety and Depression scale), and care dependency (28.5% had a Care Dependency Scale score of ≤68 points).

A high proportion of patients also had impaired HRQOL based on a number of measurements:

• 81.9% had a total St. George’s Respiratory Questionnaire (SGRQ) score of ≥44 points
• 75.0% had a total COPD Assessment Test (CAT) score of ≥18 points
• 76.7% had a total Clinical COPD Questionnaire (CCQ) score of ≥1.9 points

At baseline, the correlations between PROs and exercise test outcomes were statistically significant. For the 419 patients who completed PR, “all PROs and exercise outcomes changed significantly after PR,” according to the authors.

They concluded that in patients with mild to very severe COPD, PROs and exercise test outcomes are associated to some extent, but the correlations are generally weak to moderate. They also noted that, at baseline, there was a negative correlation with exercise test outcomes and dyspnea, but that changed following PR, “indicating that an improvement in exercise performance after PR does not necessarily imply that self-reported breathlessness decreases concurrently, like shown before.”

The authors noted that one of the limitations of their study is that patients were recruited at a specialized PR center and the study had a selected group of COPD patients, which should be taken into account when applying the results elsewhere.

They concluded that PROs and exercise test outcomes may be significantly correlated but assess different disease features in patients with COPD.

“Individual PROs need to be supported by additional functional measurements whenever possible, in order to get a more detailed insight in the effectiveness of a PR program,” the authors wrote.

Reference

Meys R, Stoffels AAF, Houben-Wilke S, et al, on behalf of the BASES-consortium. Association between patient-reported outcomes and exercise test outcomes in patients with COPD before and after pulmonary rehabilitation. Health Qual Life Outcomes. Published online September 5, 2020.