Validating respiratory sarcopenia diagnostic criteria by mortality based on a position paper by four professional organizations: Insights from the Otassha study

Aim

The Japanese Society for Respiratory Care and Rehabilitation, Japanese Association on Sarcopenia and Frailty, Japanese Society of Respiratory Physical Therapy, and Japanese Association of Rehabilitation Nutrition proposed the definition and diagnosis of respiratory sarcopenia using low respiratory muscle strength and appendicular skeletal muscle mass (ASM; ASM/height²) instead of respiratory muscle mass; however, these parameters have not been validated. This study aimed to confirm the validity of the respiratory sarcopenia definition proposed by these four professional organizations.

Methods

Participants of our cohort study in 2015 of 468 community-dwelling older people who were evaluated for sarcopenia and underwent spirometry were included in this analysis. We determined two respiratory sarcopenia models based on low skeletal muscle mass and respiratory muscle strength. Low skeletal muscle mass was defined by low ASM/height², and low respiratory muscle strength was defined by peak expiratory flow rate (PEFR) or percentage of predicted PEFR (%PEFR). Survival status was assessed 5 years after baseline assessment (in 2020). To evaluate the validity of the cut-off values for PEFR and %PEFR, we determined different respiratory sarcopenia models by sequentially varying the cut-off values for each parameter, including ASM/height², from high to low. We subsequently calculated the hazard ratio (HR) for mortality for each respiratory sarcopenia model using the Cox proportional hazards model. Additionally, we plotted the HR for each combination of cut-off values for ASM/height² and PEFR or %PEFR on a three-dimensional chart to observe the relationship between the different cut-off values and HR.

Results

A total of 31 people died during the 5-year observation period. With ASM/height² cut-off values of approximately 7.0 kg/m² for men and 5.7 kg/m² for women and %PEFR cut-off values of 66–75%, respiratory sarcopenia was associated with mortality risk (HR, 2.36–3.27, point estimation range).

Conclusions

The definition of respiratory sarcopenia by the four professional organizations is related to future health outcomes, and this definition is valid. Geriatr Gerontol Int 2024; 24: 948–953.