Division of Pediatric Nephrology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California.
Division of Pediatric Nephrology, Department of Pediatrics, Stanford University School of Medicine, Stanford, California; Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford, California; Stanford Assessment of Bone and Muscle across the Ages (SAMBA) Center, Palo Alto, California.
J Ren Nutr. 2023 Jul;33(4):538-545. doi: 10.1053/j.jrn.2023.01.012. Epub 2023 Feb 15.
Differences in creatinine and cystatin C-based estimates of glomerular filtration rate (eGFR = eGFR - eGFR) may reflect differences in muscle mass. We sought to determine if eGFR (1) reflects lean mass, (2) identifies sarcopenic individuals beyond estimates based on age, body mass index (BMI), and sex; and (3) demonstrates associations differently in those with and without chronic kidney disease (CKD).
This cross-sectional study included 3,754 participants, ages 20-85 years, with creatinine and cystatin C concentration levels, and dual-energy X-ray absorptiometry scans from National Health and Nutrition Examination Survey data (1999-2006). Dual-energy X-ray absorptiometry-derived appendicular lean mass index (ALMI) estimated muscle mass. Non-race-based CKD Epidemiology Collaboration equations estimated glomerular filtration rate using eGFR, eGFR, and both biomarkers (eGFR). CKD was defined as eGFR <60 mL/minute/1.73 m. ALMI sex-specific T-scores (compared with young adult) < -2.0 defined sarcopenia. In estimating ALMI, we compared the coefficient of determination (R) values from: 1) eGFR, 2) clinical characteristics (age, BMI, and sex), and 3) clinical characteristics plus eGFR. Using logistic regression, we evaluated each model's C-statistic to diagnose sarcopenia.
eGFR was negatively and weakly associated with ALMI (No CKD: R = 0.006, p-value 0.002; CKD: R = 0.001, P value .9). Clinical characteristics explained most of the variation in ALMI (No CKD: R = 0.851, CKD: R = 0.828), and provided strong discrimination of sarcopenia (No CKD C-statistic: 0.950; CKD C-statistic: 0.943). Adding eGFR improved the R by 0.025, and the C-statistic by 0.003. Tests for interaction between eGFR and CKD were not significant (all P values > .05).
Although eGFR has statistically significant associations with ALMI and sarcopenia in univariate analyses, multivariate analyses demonstrate that eGFR does not capture more information beyond routine clinical characteristics (age, BMI, and sex).
基于肌氨酸酐和胱抑素 C 的肾小球滤过率估计值（eGFR = eGFR - eGFR）的差异可能反映肌肉质量的差异。我们旨在确定 eGFR 是否（1）反映瘦体重，（2）在基于年龄、体重指数（BMI）和性别的估计之外识别出肌少症个体；（3）在有和没有慢性肾脏病（CKD）的人群中表现出不同的关联。
这项横断面研究纳入了 3754 名年龄在 20-85 岁之间的参与者，他们来自于国家健康和营养检查调查数据（1999-2006 年），并提供了肌氨酸酐和胱抑素 C 浓度水平以及双能 X 射线吸收法（DXA）扫描数据。DXA 衍生的四肢瘦体重指数（ALMI）估计肌肉质量。非种族基的 CKD 流行病学协作组方程使用 eGFR、eGFR 和两种生物标志物（eGFR）估计肾小球滤过率。eGFR<60mL/minute/1.73m 定义为 CKD。ALMI 性别特异性 T 分数（与年轻成年人相比）< -2.0 定义为肌少症。在估计 ALMI 时，我们比较了来自以下方面的决定系数（R）值：1）eGFR，2）临床特征（年龄、BMI 和性别），以及 3）临床特征加 eGFR。我们使用逻辑回归评估了每个模型的 C 统计量以诊断肌少症。
eGFR 与 ALMI 呈负相关且相关性较弱（无 CKD：R=0.006，P 值<.002；有 CKD：R=0.001，P 值>.9）。临床特征解释了 ALMI 变化的大部分（无 CKD：R=0.851，有 CKD：R=0.828），并且能够很好地区分肌少症（无 CKD C 统计量：0.950；有 CKD C 统计量：0.943）。增加 eGFR 将 R 值提高了 0.025，C 统计量提高了 0.003。eGFR 和 CKD 之间交互作用的检验均无统计学意义（所有 P 值均>.05）。
尽管 eGFR 在单变量分析中与 ALMI 和肌少症具有统计学显著关联，但多变量分析表明，eGFR 并未捕获超出常规临床特征（年龄、BMI 和性别）之外的更多信息。
