Physical Activity Characteristics across GOLD Quadrants Depend on the Questionnaire Used

Abstract

Background: The GOLD multidimensional classification of COPD severity combines the exacerbation risk with the symptom experience, for which 3 different questionnaires are permitted. This study investigated differences in physical activity (PA) in the different GOLD quadrants and patient's distribution in relation to the questionnaire used.

Methods: 136 COPD patients (58±21% FEV1 predicted, 34F/102M) completed COPD assessment test (CAT), clinical COPD questionnaire (CCQ) and modified Medical Research Council (mMRC) questionnaire. Exacerbation history, spirometry and 6MWD were collected. PA was objectively measured for 2 periods of 1 week, 6 months apart, in 5 European centres; to minimise seasonal and clinical variation the average of these two periods was used for analysis.

Results: GOLD quadrants C+D had reduced PA compared with A+B (3824 [2976] vs. 5508 [4671] steps.d-1, p<0.0001). The choice of questionnaire yielded different patient distributions (agreement mMRC-CAT κ = 0.57; CCQ-mMRC κ = 0.71; CCQ-CAT κ = 0.72) with different clinical characteristics. PA was notably lower in patients with an mMRC score ≥2 (3430 [2537] vs. 5443 [3776] steps.d-1, p <0.001) in both the low and high risk quadrants.

Conclusions: Using different questionnaires changes the patient distribution and results in different clinical characteristics. Therefore, standardization of the questionnaire used for classification is critical to allow comparison of different studies using this as an entry criterion.

Clinical trial registration: ClinicalTrials.gov NCT01388218.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist. The funding of the present work does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. The new GOLD assessment.

The classification combines the symptomatic assessment with the patients’ spirometric classification and/or risk of exacerbations, resulting in 4 quadrants. To classify patients first symptoms should be assessed with the mMRC, CAT or CCQ scale and investigator should determine if the patient belongs to the left (less symptoms) or right (more symptoms) side of the box. Next the risk of exacerbations should be assessed to determine if the patient belongs to the lower part of the box (low risk) or the upper part of the box (higher risk). When assessing symptoms the mMRC, CAT or the CCQ scale can be used; when assessing risk the highest risk according to GOLD grade or exacerbation history should be chosen.

Fig 2. Physical activity across different GOLD classifications.

GOLD = Spirometric GOLD classification; mMRC = combined assessment using mMRC; CAT = combined assessment using CAT; CCQ = combined assessment using CCQ; Significant differences (post hoc analysis) are indicated with a solid line.

Fig 3. Physical activity across different mMRC, CAT and CCQ cut-offs.

Upper panels present physical activity data, significant differences (post hoc analysis) are indicated with a solid line; lower panels depict proportion of patients defined as sedentary (black bars). Dotted line present cut off used in the GOLD classification; A/C and B/D indicate respectively quadrants A or C and B or D.

Fig 4. Patient distribution across the different GOLD classifications.

The size of the squares represent the patient distribution relative to quadrant A. mMRC = combined assessment using mMRC; CAT = combined assessment using CAT; CCQ = combined assessment using CCQ.