Sarcopenia may be associated with the long-term prognosis of renal transplant recipients, so it is essential to early and rapidly screening for sarcopenia in these patients. Studies suggest that calf circumference may be an effective indicator in early screening for sarcopenia.

To investigate the relationship between calf circumference and sarcopenia, and to explore the feasibility of using calf circumference as a predictive marker for sarcopenia in kidney transplant recipients.

We selected 80 kidney transplant recipients who were treated in the department of organ transplantation of Guangdong Second Provincial General Hospital from October 2021 to June 2022 as the subjects. Demographic information (sex, age, educational attainment, marital status) , anthropometric indicators〔height, weight, body mass index (BMI) , calf circumference, mid-arm circumference (MAC) , triceps skin-fold thickness (TSF) , arm muscle circumference (AMC) , waist circumference, hip circumference, waist-to-hip ratio〕, muscle strength indicators (grip strength, pinch strength) , body composition indicators〔appendicular skeletal muscle mass (ASM) , skeletal muscle mass index (SMI) , 50 kHz phase angle (PhA) , body cell mass (BCM) , intracellular and extracellular fluids〕 were collected. Sarcopenia was diagnosed by the Asian Working Group for Sarcopenia 2019 consensus. Kidney transplant recipients who meet the diagnostic criteria were included in the sarcopenia group, and those who do not meet the diagnostic criteria were included in the non-sarcopenia group. Demographic information, anthropometric indicators, muscle strength indicators, and body composition indicators between sarcopenia and non-sarcopenia patient groups were compared by sex. Pearson correlation analysis and Spearman rank correlation analysis were used to observe the correlation of calf circumference with diagnostic indicators of sarcopenia (ASM, SMI, grip strength) . Univariate and multivariate logistic regression analyses were used to explore the influencing factors of sarcopenia. The predictive value of calf circumference for sarcopenia in kidney transplant of male and female subjects was analyzed by using the receiver operating characteristic (ROC) curve, and the area under the curve (AUC) , sensitivity, specificity and optimal cut-off values were calculated.

A total of 80 patients〔51 men (63.8%) and 29 women (36.2%) 〕 with an average age of (44.3±11.7) years were included, including 19 (23.75%) with sarcopenia, and 61 (76.25%) without. Sex-based analysis found that male patients with sarcopenia group had lower values of weight, BMI, calf circumference, MAC, TSF, hip circumference, grip strength, pinch strength, ASM, SMI, PhA, BCM, extracellular fluid and intracellular fluid than those without (P<0.05) . Female patients with sarcopenia had lower values of weight, BMI, calf circumference, waist circumference, hip circumference, waist-to-hip ratio, ASM, SMI, BCM, extracellular fluid and intracellular fluid than those without (P<0.05) . Correlation analysis showed that the calf circumference had a positive correlation with ASM, SMI and grip strength in both male kidney transplants (r_s=0.545, P<0.001; r_s=0.540, P<0.001; r_s=0.340, P=0.015) and female kidney transplants (r_s=0.499, P=0.006; r_s=0.578, P=0.001; r=0.426, P=0.021) . Multivariate Logistic regression analysis showed that calf circumference was associated with sarcopenia in kidney transplant〔OR=0.699, 95%CI (0.051, 0.975) , P=0.035〕. ROC analysis revealed that the AUC of calf circumference predicting sarcopenia in kidney transplant of male subjects was 0.799, with the optimal cut-off value, sensitivity and specificity of 33.3 cm, 83.3% and 74.4%, respectively. And the AUC of calf circumference predicting sarcopenia in kidney transplant of female patients was 0.851, with the optimal cut-off value, sensitivity and specificity of 32.2 cm, 100.0% and 59.1%, respectively.

Calf circumference is associated with sarcopenia and can be used as a predictive marker for early screening of sarcopenia in kidney transplant recipients. However, its predictive value needs to be verified further by large-sample cohort studies, and thus to better promote early clinical screening of sarcopenia in kidney transplant recipients to effectively improve their quality of life and prognosis.

肾移植受者的长期预后可能与肌肉减少症（肌少症）相关，因此早期快速筛查肾移植受者的肌少症非常重要，研究提示小腿围可能是早期筛查肌少症的一个良好指标。

分析肾移植受者小腿围与肌少症的相关性，并探讨小腿围预测肾移植受者肌少症的可行性。

选取2021年10月—2022年6月在广东省第二人民医院器官移植科治疗的80例肾移植受者为研究对象。收集研究对象的人口学信息（性别、年龄、受教育程度、婚姻状况）、人体测量学指标〔身高、体质量、BMI、小腿围、上臂围（MAC）、三头肌皮褶厚度（TSF）、上臂肌围（AMC）、腰围、臀围、腰臀比〕、肌肉力量指标（握力、捏力）、人体成分指标〔四肢骨骼肌质量（ASM）、骨骼肌质量指数（SMI）、50 kHz相位角（PhA）、人体细胞质量（BCM）、细胞内液，细胞外液〕。采用2019年亚洲肌少症工作组共识诊断标准确诊肌少症，符合诊断标准的肾移植受者纳入肌少症患者组，不符合诊断标准的纳入非肌少症患者组，按性别分层比较肌少症患者组与非肌少症患者组人口学信息、人体测量学指标、肌肉力量指标、人体成分指标的差异，并采用Pearson相关分析和Spearman秩相关分析观察肾移植受者小腿围与肌少症诊断指标（ASM、SMI、握力）的相关性；采用Logistic回归分析探讨肾移植受者肌少症的影响因素，并采用受试者工作特征（ROC）曲线分析小腿围对不同性别肾移植受者肌少症的预测价值，计算ROC曲线下面积（AUC）、灵敏度、特异度、最佳截断值。

80例患者中男51例（63.8%）、女29例（36.2%），平均年龄为（44.3±11.7）岁，非肌少症患者61例（76.25%），肌少症患者19例（23.75%）；按照性别分层后，男性肌少症患者组的体质量、BMI、小腿围、MAC、TSF、臀围、握力、捏力、ASM、SMI、PhA、BCM、细胞外液、细胞内液低于男性非肌少症患者组（P<0.05）；女性肌少症患者组的体质量、BMI、小腿围、腰围、臀围、腰臀比、ASM、SMI、BCM、细胞外液、细胞内液低于女性非肌少症患者组（P<0.05）。相关性分析结果显示，男性、女性肾移植受者的小腿围与ASM、SMI和握力均呈正相关（男性：r_s=0.545，P<0.001；r_s=0.540，P<0.001；r_s=0.340，P=0.015；女性：r_s=0.499，P=0.006；r_s=0.578，P=0.001；r=0.426，P=0.021）。多因素Logistic回归分析结果显示小腿围是肾移植受者肌少症的影响因素〔OR=0.699，95%CI（0.051，0.975），P=0.035〕。小腿围预测不同性别肌少症患者的ROC曲线的结果显示，小腿围预测男性肾移植受者肌少症的AUC、最佳截断值、灵敏度及特异度分别为0.799、33.3 cm、83.3%、74.4%。小腿围预测女性肾移植受者肌少症的AUC、最佳截断值、灵敏度及特异度分别为0.851、32.2 cm、100.0%、59.1%。

小腿围是肾移植受者肌少症的影响因素，对肾移植受者肌少症的早期筛查有一定预测价值。未来尚需更大样本量的队列研究来验证小腿围在早期筛查肾移植受者肌少症中的作用，以便于更好地推动肾移植受者肌少症临床早期筛查工作的开展，从而改善其生活质量和预后状况。