Co-occurrence of Whole-body Muscle Wasting and Respiratory Muscle Weakness Affecting the Clinical Characteristics of Patients with Chronic Obstructive Pulmonary Disease.

Abstract

Objectives: The effect of the co-occurrence of whole-body muscle wasting and respiratory muscle weakness on the clinical characteristics of patients with chronic obstructive pulmonary disease (COPD) is unclear. We investigated this association in patients with chronic respiratory diseases.

Methods: 47 outpatients with mild to very severe COPD were classified into four groups according to their fat-free mass index and respiratory muscle strength: 19 without muscle wasting and respiratory muscle weakness (normal), 6 with muscle wasting only (MW), 11 with respiratory weakness only (RW), and 11 with muscle wasting and respiratory weakness (MW + RW). We measured their body composition, pulmonary function, lower muscle strength, submaximal exercise capacity, physical activity in daily life, nutritional status, frailty status, and health-related quality of life (QOL). Multiple linear regression analyses examined the association of muscle wasting and/or respiratory muscle weakness with participant characteristics, using each participant's characteristics as an explained variable adjusted for confounding variables (Normal as the reference).

Results: The regression analysis revealed that the percentage of vital capacity, lower muscle strength, submaximal exercise capacity, nutritional status, and frailty status were worse in the MW + RW group than in the Normal group. The MR + RW group had the largest number of variables with significant differences compared to the Normal group.

Conclusions: These data suggest that the co-occurrence of whole-body muscle wasting and respiratory muscle weakness was significantly associated with deteriorating clinical characteristics in patients with COPD.