Section of NILS-LSA (National Institute for Longevity Sciences-Longitudinal Study of Aging), Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu, Aichi, 474-8511, Japan.
Department of Orthopedics, National Center for Geriatrics and Gerontology, 7-430 Morioka-cho, Obu, Aichi, 474-8511, Japan.
BMC Geriatr. 2018 Jan 5;18(1):8. doi: 10.1186/s12877-017-0699-6.
Age-related declines in skeletal muscle mass and strength, representing "sarcopenia," are a growing concern in aging societies. However, the prevalence of low muscle mass based on the height-adjustment has been shown to be extremely low, and a more appropriate definition of low muscle mass is needed, particularly for Asian women. The aim of this study was to explore the most appropriate adjustment of appendicular lean mass (ALM) for predicting mortality or disability risk using ALM or any of 5 adjustments of ALM among community-dwelling Japanese.
Subjects comprised 1026 men and 952 women between 40 and 79 years old at baseline (1997-2000) who participated in the National Institute for Longevity Sciences - Longitudinal Study of Aging, Japan. ALM (kg) and 5 adjusted indices of ALM (ALM/leg length, ALM/height, ALM/height, ALM/weight, and ALM/body mass index [BMI]) were assessed at baseline. Disability was defined by long-term care insurance certification based on responses to a survey mailed in 2013, and death records were obtained as vital statistics until December 2014. Crude and adjusted Cox proportional hazard models were used to estimate hazard ratios for mortality or disability by sex-stratified quintiles of each ALM index (ALM and adjusted ALM) or sarcopenia-related indices. The area under the curve (AUC) was calculated with the multivariate-adjusted logistic regression model. Additionally, mixed-effects analyses were used to clarify the age-related ALM indices decline over 12 years (n = 1838).
Crude Cox proportional hazard models and multivariate-adjusted logistic model (AUC) indicated that higher ALM and ALM/BMI in women, and higher ALM, ALM/leg length, ALM/height, and ALM/BMI in men were associated with lower risks for mortality or disability than ALM/height. The mixed effect model indicated all ALM indices in men, and ALM, ALM/leg length, and ALM/height in women could better predict age-related lean muscle mass decline.
Unadjusted ALM in women, and ALM/leg length, ALM/height, ALM/BMI, and ALM in men may be more appropriate for predicting future mortality or disability than ALM/height. Considering the age-related muscle mass decline, unadjusted ALM would be the first variable to assess, regardless of sex, in this Japanese cohort study.
与年龄相关的骨骼肌量和力量下降，即“肌肉减少症”，在老龄化社会中日益受到关注。然而，基于身高调整的低肌肉量的患病率被证明极低，因此需要更合适的低肌肉量定义，特别是对于亚洲女性。本研究旨在探讨使用四肢瘦体重（ALM）或社区居住的日本人群中 ALM 的 5 种调整指标中的任何一种，哪种调整指标最适合预测死亡率或残疾风险。
本研究的受试者为 1997-2000 年基线时年龄在 40-79 岁之间的 1026 名男性和 952 名女性，他们参加了日本国立长寿科学研究所-老龄化纵向研究。在基线时评估了 ALM（kg）和 5 种调整后的 ALM 指数（ALM/腿长、ALM/身高、ALM/身高、ALM/体重和 ALM/体重指数[BMI]）。残疾的定义是根据 2013 年邮寄的调查的长期护理保险认证，死亡记录作为生命统计数据，截至 2014 年 12 月。使用按性别分层的每个 ALM 指数（ALM 和调整后的 ALM）或肌肉减少症相关指数的五分位数的粗 Cox 比例风险模型和调整后的 Cox 比例风险模型来估计死亡率或残疾的风险比。使用多变量调整的逻辑回归模型计算曲线下面积（AUC）。此外，还使用混合效应分析来阐明 12 年内与年龄相关的 ALM 指数下降（n=1838）。
粗 Cox 比例风险模型和多变量调整的逻辑模型（AUC）表明，女性的 ALM 和 ALM/BMI 较高，男性的 ALM、ALM/腿长、ALM/身高和 ALM/BMI 较高，与死亡率或残疾风险较低相关，而不是 ALM/身高。混合效应模型表明，男性的所有 ALM 指数以及女性的 ALM、ALM/腿长和 ALM/身高都可以更好地预测与年龄相关的肌肉质量下降。
女性未经调整的 ALM，以及男性的 ALM/腿长、ALM/身高、ALM/BMI 和 ALM，可能比 ALM/身高更适合预测未来的死亡率或残疾。考虑到与年龄相关的肌肉质量下降，无论性别如何，在这项日本队列研究中，未经调整的 ALM 都是评估的第一个变量。
