Hiroshi Kusunoki1, Yasuharu Tabara2, Shotaro Tsuji3, Yosuke Wada4, Kayoko Tamaki5, Koutatsu Nagai6, Masako Itoh6, Kyoko Sano6, Manabu Amano7, Hatsuo Maeda7, Hideyuki Sugita8, Yoko Hasegawa9, Hiromitsu Kishimoto8, Soji Shimomura10, Michiya Igase11, Ken Shinmura12. 1. Division of General Medicine, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan. Electronic address: kusunoki1019@yahoo.co.jp. 2. Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan. 3. Department of Orthopaedic Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan. 4. Department of General Medicine and Community Health Science, Sasayama Medical Center Hyogo College of Medicine, Sasayama, Hyogo, Japan; Department of Rehabilitation Medicine, Sasayama Medical Center Hyogo College of Medicine, Sasayama, Hyogo, Japan. 5. Division of General Medicine, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan. 6. School of Rehabilitation, Hyogo University of Health Sciences, Kobe, Hyogo, Japan. 7. School of Pharmacy, Hyogo University of Health Sciences, Kobe, Hyogo, Japan. 8. Department of Dentistry and Oral Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan. 9. Department of Dentistry and Oral Surgery, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan; Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Niigata, Japan. 10. Department of General Medicine and Community Health Science, Sasayama Medical Center Hyogo College of Medicine, Sasayama, Hyogo, Japan. 11. Department of Anti-aging Medicine, Ehime University Graduate School of Medicine, Toon, Ehime, Japan. 12. Division of General Medicine, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan; Department of General Medicine and Community Health Science, Sasayama Medical Center Hyogo College of Medicine, Sasayama, Hyogo, Japan.
Abstract
OBJECTIVES: Sarcopenia is defined as a combination of low skeletal muscle mass index (SMI), weak muscle strength, and reduced physical function. Recently, many studies have reported that the creatinine/cystatin C ratio (Cr/CysC) is useful for evaluating muscle mass. We designed a cross-sectional study with separate model development and validation groups to develop a prediction equation to estimate bioimpedance analysis (BIA)-measured SMI with Cr/CysC. DESIGN: The current study was a retrospective cross-sectional study. SETTING AND PARTICIPANTS: The model development group included 908 subjects (288 men and 620 women) from the Frail Elderly in the Sasayama-Tamba Area (FESTA) study, and the validation group included 263 subjects (112 men and 151 women) from participants in the medical checkup program at the Anti-Aging Center in Ehime Prefecture. MEASURES: Multivariate regression analysis indicated that age, hemoglobin (Hb), body weight (BW), and Cr/CysC were independently associated with SMI in both men and women. The SMI prediction equation was developed as follows: Men:4.17-0.012×Age+1.24×(Cr/CysC)-0.0513×Hb+0.0598×BW Women:3.55-0.00765×Age+0.852×(Cr/CysC)-0.0627×Hb+0.0614×BW RESULTS: The SMI prediction equation was applied to the validation group and strong correlations were observed between the BIA-measured and predicted SMI (pSMI) in men and women. According to the receiver operator characteristic (ROC) analysis, the areas under the curve were 0.93 (specificity 89.0%, sensitivity 87.2%) among men and 0.88 (specificity 83.6%, sensitivity 79.6%) among women for using pSMI to identify low SMI in the model development group. The pSMI also indicated high accuracy in ROC analysis for low SMI in the validation group. The Bland-Altman plot regression showed good agreement between BIA-measured and pSMI. CONCLUSIONS AND IMPLICATIONS: Our new prediction equation to estimate SMI is easy to calculate in daily clinical practice and would be useful for diagnosing sarcopenia.
OBJECTIVES: Sarcopenia is defined as a combination of low skeletal muscle mass index (SMI), weak muscle strength, and reduced physical function. Recently, many studies have reported that the creatinine/cystatin C ratio (Cr/CysC) is useful for evaluating muscle mass. We designed a cross-sectional study with separate model development and validation groups to develop a prediction equation to estimate bioimpedance analysis (BIA)-measured SMI with Cr/CysC. DESIGN: The current study was a retrospective cross-sectional study. SETTING AND PARTICIPANTS: The model development group included 908 subjects (288 men and 620 women) from the Frail Elderly in the Sasayama-Tamba Area (FESTA) study, and the validation group included 263 subjects (112 men and 151 women) from participants in the medical checkup program at the Anti-Aging Center in Ehime Prefecture. MEASURES: Multivariate regression analysis indicated that age, hemoglobin (Hb), body weight (BW), and Cr/CysC were independently associated with SMI in both men and women. The SMI prediction equation was developed as follows: Men:4.17-0.012×Age+1.24×(Cr/CysC)-0.0513×Hb+0.0598×BW Women:3.55-0.00765×Age+0.852×(Cr/CysC)-0.0627×Hb+0.0614×BW RESULTS: The SMI prediction equation was applied to the validation group and strong correlations were observed between the BIA-measured and predicted SMI (pSMI) in men and women. According to the receiver operator characteristic (ROC) analysis, the areas under the curve were 0.93 (specificity 89.0%, sensitivity 87.2%) among men and 0.88 (specificity 83.6%, sensitivity 79.6%) among women for using pSMI to identify low SMI in the model development group. The pSMI also indicated high accuracy in ROC analysis for low SMI in the validation group. The Bland-Altman plot regression showed good agreement between BIA-measured and pSMI. CONCLUSIONS AND IMPLICATIONS: Our new prediction equation to estimate SMI is easy to calculate in daily clinical practice and would be useful for diagnosing sarcopenia.