Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland.
J Am Soc Nephrol. 2023 Mar 1;34(3):495-504. doi: 10.1681/ASN.0000000000000037. Epub 2023 Jan 26.
Low muscle mass is related to frailty and increased mortality in older adults. However, muscle mass is not easily assessed in routine clinical practice. This paper describes a novel creatinine muscle index (CMI) on the basis of serum creatinine and cystatin C. CMI was moderately associated with frailty among older adults. A significantly higher proportion of individuals with weak grip strength were in the lowest tertile of CMI. The index was also associated with mortality. These results are consistent with the hypothesis that creatinine filtration may be an index of muscle mass, which may have utility in clinical practice.
Low muscle mass is related to frailty and increased mortality in older adults. However, muscle mass is not easily assessed in routine clinical practice.
This study describes a novel creatinine muscle index (CMI) on the basis of serum creatinine and cystatin C in a community-based sample of older adults from the Atherosclerosis Risk in Communities Study. Analyses included 4639 participants who attended visit 5 (2011-2013) and 12,786 participants who attended visit 2 (1990-1992). CMI was defined as creatinine filtration (the product of serum creatinine times eGFR on the basis of cystatin C) and was analyzed in sex-specific tertiles. Cross-sectional associations of CMI with a frailty trichotomy, defined by the number (robust [0]/prefrail [1-2]/frail [3-5]) of five frailty components (weight loss, slowness, exhaustion, weakness, and low physical activity), were studied using polychotomous logistic regression and binary logistic regression with each frailty component. Cox regression was used to estimate associations of CMI at visit 5 and visit 2 with mortality. Models were adjusted for demographics, clinical variables, and comorbid conditions.
CMI (tertile 1 versus 3) was moderately associated with frailty (visit 5: adjusted odds ratio 4.23 [95% confidence interval (CI), 2.02 to 8.87] in men and 2.34 [95% CI, 1.41 to 3.89] in women) and with mortality (visit 5: adjusted hazard ratio 1.45 [95% CI, 1.08 to 1.94] in men and 1.55 [95% CI, 1.13 to 2.12] in women; similar results were seen at visit 2).
Lower CMI was associated with frailty and increased mortality, two clinical outcomes known to be associated with decreased muscle mass. Creatinine filtration may be an index of muscle mass and have utility in clinical practice, particularly at low levels.
肌肉量少与老年人的虚弱和死亡率增加有关。然而，肌肉量在常规临床实践中不易评估。本文基于血清肌酐和胱抑素 C 描述了一种新的肌肌酐指数（CMI）。CMI 与老年人的虚弱中度相关。握力较弱的个体中，有相当大比例的人处于 CMI 的最低三分位。该指数也与死亡率相关。这些结果与肌滤过率可能是肌肉量的指标的假设一致，这在临床实践中可能具有实用性。
肌肉量少与老年人的虚弱和死亡率增加有关。然而，肌肉量在常规临床实践中不易评估。
本研究基于社区为基础的动脉粥样硬化风险社区研究（Atherosclerosis Risk in Communities Study）中老年人的样本，基于血清肌酐和胱抑素 C 描述了一种新的肌肌酐指数（CMI）。分析包括参加第五次（2011-2013 年）访问的 4639 名参与者和参加第二次（1990-1992 年）访问的 12786 名参与者。CMI 定义为肌酐滤过率（基于胱抑素 C 的血清肌酐与 eGFR 的乘积），并按性别分为三分位。使用多分类逻辑回归和每个虚弱成分的二元逻辑回归研究 CMI 与虚弱三分位的横断面关联，虚弱三分位定义为五个虚弱成分（体重减轻、缓慢、疲惫、虚弱和低体力活动）的数量（强壮[0]/虚弱前期[1-2]/虚弱[3-5]）。使用 Cox 回归估计第五次和第二次访问时 CMI 与死亡率的关联。模型调整了人口统计学、临床变量和合并症情况。
CMI（三分位 1 与 3）与虚弱中度相关（第五次访问：男性调整后的优势比为 4.23[95%置信区间（CI），2.02 至 8.87]，女性为 2.34[95%CI，1.41 至 3.89]）和死亡率（第五次访问：男性调整后的危险比为 1.45[95%CI，1.08 至 1.94]，女性为 1.55[95%CI，1.13 至 2.12]）。在第二次访问时也观察到了类似的结果。
较低的 CMI 与虚弱和死亡率增加相关，这两个临床结果与肌肉量减少有关。肌滤过率可能是肌肉量的指标，在临床实践中具有实用性，尤其是在低水平时。
