Prevalence, Impact, and Screening Methods of Sarcopenia in Japanese Patients With Parkinson's Disease: A Prospective Cross-Sectional Study.

Introduction: Sarcopenia is a skeletal muscle disease manifesting as low muscle mass and impaired muscle function. It has been reported that sarcopenia correlates with a low quality of life (QOL) and an increased risk of falls in patients with Parkinson's disease (PD). Nevertheless, few studies have investigated the prevalence, impact, and screening methods of sarcopenia in Japanese patients with PD.

Methods: Sarcopenia was diagnosed based on the Asian Working Group for Sarcopenia 2019 consensus. We compared demographic characteristics, severity of PD, levodopa equivalent daily dose, QOL, fatigue, impulsive and compulsive behaviors, body mass index (BMI), calf circumference, skeletal muscle mass index (SMI), handgrip strength, a 4-meter gait speed, a five-time sit-to-stand test (FTSST), short physical performance battery, and SARC-F questionnaire scores between sarcopenia and non-sarcopenia groups. Furthermore, to investigate the best tool for screening sarcopenia in PD, the sensitivity and specificity of calf circumference, handgrip strength, FTSST, and SARC-F questionnaire were compared.

Results: The prevalence of sarcopenia in PD was 31.9% (15/47). The sarcopenia group showed significantly higher age (77.3 ± 5.12 versus 70.3 ± 8.17, p = 0.0042), lower BMI (19.3 ± 2.99 versus 23.3 ± 3.18, p = 0.0002), higher rate of decreased calf circumference (86.6% versus 34.3%, p = 0.0013) and SMI (100% versus 6.25%, p < 0.0001), and worse FTSST (15.5 ± 5.57 versus 12.0 ± 4.12, p = 0.0219). The other parameters were not significantly different. Among screening tools, calf circumference had the highest sensitivity (86%) and specificity (65%). All screening tools had higher sensitivity and specificity in men than in women. The SARC-F questionnaire was not useful in distinguishing sarcopenia but was significantly correlated with the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale Part 3 (r = 0.41, p = 0.0037) and the 39-item Parkinson's Disease QOL Scale (r = 0.71, p < 0.0001).

Conclusion: This study investigated the characteristics of PD patients with sarcopenia in Japan. Calf circumference was found to be the most useful tool for screening sarcopenia in PD. Handgrip strength and FTSST also showed high sensitivities, particularly in men. Conversely, the SARC-F questionnaire is not suitable for diagnosing sarcopenia in PD.