Reference Equations for Assessing the Physical Activity of Japanese Patients with Chronic Obstructive Pulmonary Disease

Abstract

Yoshiaki Minakata, Seigo Sasaki, Yuichiro Azuma, Kazumi Kawabe, Hideya Ono Department of Respiratory Medicine, National Hospital Organization Wakayama Hospital, Wakayama, JapanCorrespondence: Yoshiaki Minakata Tel [phone]Fax [phone]Email [email protected]: To improve physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD), providing a target PA value based on the individual patient’s condition may be a useful interventional strategy. However, to determine the target value, a predictive PA value for each patient is required.Research Question: What is the reference equation consisting of PA-related factors to determine the predictive PA value for each patient with COPD?Material and Methods: In this prospective cross-sectional observational study, we measured the PA with a triaxial accelerometer and several other factors including demographic factors, pulmonary function, dyspnea, exercise capacity, muscle strength, nutrition, and indicators of several comorbidities in stable Japanese outpatients with COPD aged ≥ 40 years old and detected PA-related factors by a multiple regression analysis and stepwise method. We created reference equations for four indices of PA using multiple linear regression equations.Results: Two hundred and twenty-seven patients were registered. The equations of duration at ≥ 2.0 metabolic equivalents (METs) and step count consisted of 4 factors: 6-minute walk distance, modified Medical Research Council dyspnea scale, anxiety score of the Hospital Anxiety and Depression Scale, and the forced expiratory volume in 1 second % of predicted value. Those of duration at ≥ 3.0 METs and total activity at ≥ 3.0 METs consisted of 5 factors: the above 4 factors and age or brain natriuretic peptide. There was no fixed bias or proportional bias between the measured and predictive values in patients with non-high measured PA values.Conclusion: We determined reference equations for four indicators of PA using PA-related factors in Japanese patients with COPD. The predictive values calculated using the equations could be useful for deciding target PA values for each patient.Clinical Trial Registration: UMIN-CTR; No.: UMIN000025459; URL: https://www.umin.ac.jp/ctr/index.htm.Keywords: predictive value, COPD, metabolic equivalents, step count

Keywords

• predictive value
• copd
• metabolic equivalents
• step count