Relationships between sarcopenia and pulmonary function, exercise capacity, and prognosis in patients with COPD

Abstract

Background Sarcopenia is defined as the loss of limb skeletal muscle mass and muscle weakness. Aging and some other factors are known to contribute to its development. Although sarcopenia is appeared in patients with COPD, its relationships with pulmonary function, exercise capacity, and prognosis has not been well understood.

Objectives To determine relationships between sarcopenia and pulmonary function, exercise capacity, and prognosis in patients with COPD.

Methods Thirty-six stable male patients with COPD (69.8 years old, % FEV1;52.7%) were recruited between 2003 and 2005. Body composition was evaluated by the bio-impedance method (BIA). Exercise capacity was also evaluated by cardio-pulmonary exercise test with ergometer. Sarcopenia was defined with Skeletal Muscle Index(SMI)less than 7 kg/m² (Tanimoto Y, et al. Arch Gerontol Geriatr 2012; 55:e9-13). Acute exacerbation histories and mortality was checked with medical record retrospectively up to 12 years.

Results Twenty-four cases out of patients with COPD (66.7%) was sarcopenia. Sarcopenia group is significantly older (p<0.05), lower BMI (p<0.05), lower exercise capacity (p<0.01). However, there was no significant difference in %FEV1 and %DLCO between the two groups. There was tendency for more COPD acute exacerbation requiring hospitalization in sarcopenia group.

Conclusions Sarcopenia is recognized at a high rate in patients with COPD in Japanese population. Although sarcopenia was independent of pulmonary function, it was related to impaired exercise capacity and frequent acute exacerbation.