Definition of Respiratory Sarcopenia With Peak Expiratory Flow Rate

Objectives Respiratory muscle strength decreases with advancing age, and respiratory muscle dysfunction may indicate respiratory sarcopenia. However, there is no consensus regarding the definition of respiratory sarcopenia. We aimed to create a definition of respiratory sarcopenia based on the peak expiratory flow rate (PEFR). Design Cross-sectional study. Setting and participants Community-based study including 681 community-dwelling older people. Methods Body composition, spirometry, grip strength, and walking speed were measured. Participants reported comorbidities and long-term insurance certification. Conventional sarcopenia was defined using skeletal muscle mass, grip strength, and walking speed adjusted for the Japanese population. Receiver operating characteristic (ROC) curve analysis of the cut-off values of PEFR for conventional sarcopenia and long-term care insurance certification were performed for both sexes without airway obstruction. In the ROC curve analysis, potential cut-off values were lowest quartile, lowest quintiles, and the standard deviation of PEFR. Multiple logistic regression analysis was performed with respiratory sarcopenia as a dependent variable defined by each cut-off value and other variants as independent variables. Results The ROC curve analysis for conventional sarcopenia and long-term care insurance certification showed significance for both sexes, and we determined cut-off values from those results. The multiple logistic regression model using PEFR values 1 standard deviation below the mean had the highest accuracy; thus, we accepted these cut-off values (4.40 L/s for men, 3.21 L/s for women) for the definition of respiratory sarcopenia. Conclusions/Implications The definition of respiratory sarcopenia based on PEFR was useful and correlated with conventional sarcopenia and long-term care insurance certification among community-dwelling older people. In this study, respiratory sarcopenia was determined by PEFR alone. Other parameters may need to be considered.