Differences in physical activity according to mMRC grade in patients with COPD.
BACKGROUND
Physical activity (PA) is impaired from the early stages of COPD, is associated with a worsening of disease prognosis, and causes COPD patients to restrict their daily activities in order to avoid breathlessness. The development of a simple tool to estimate physical activity level (PAL) could be useful for the management of COPD.


OBJECTIVE
We investigated the differences in PA according to the modified Medical Research Council (mMRC) grade in patients with COPD.


METHODS
A cross-sectional study was performed on stable outpatients with COPD. PA was measured for 2 weeks using a triaxial accelerometer, and dyspnea grade was evaluated in all patients using the mMRC scale.


RESULTS
Ninety-eight patients were recruited. Significant differences in PA duration were observed at all intensities according to the mMRC grade. Despite treatment with controller medications, 59.2% of COPD patients had low PAL, which was <1.5 metabolic equivalents multiplied by hour per day. COPD patients with an mMRC grade ≥2, which was the most balanced cutoff point in the receiver operating characteristic curve, showed a higher reduction rate of PAL (80.0% at mMRC grade 2, 71.4% at mMRC grade 3, and 100% at mMRC grade 4).


CONCLUSIONS
PA differed according to the mMRC grade, and mMRC grade ≥2 could predict a low PAL. Therefore, assessment of breathlessness by the mMRC questionnaire would be useful to stratify the risks of reduced PA in COPD.
Third Department of Internal Medicine, Wakayama Medical University, School of Medicine, Wakayama.
Atsushi
A
Hayata
Department of Respiratory Medicine, National Hospital Organization Wakayama Hospital, Wakayama.
Yoshiaki
Y
Minakata
Department of Respiratory Medicine and Infectious Disease, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan.
Kazuto
K
Matsunaga
Third Department of Internal Medicine, Wakayama Medical University, School of Medicine, Wakayama.
Masanori
M
Nakanishi
Third Department of Internal Medicine, Wakayama Medical University, School of Medicine, Wakayama.
Nobuyuki
N
Yamamoto
D056044:Actigraphy; D000203:Activities of Daily Living; D000368:Aged; D019540:Area Under Curve; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology; D015444:Exercise; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
METs; accelerometer; dyspnea; questionnaire
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