A Sarcopenia Index Derived from Malnutrition Parameters in Elderly Haemodialysis Patients

**Background:** Sarcopenia—loss of muscle mass and strength—is common in elderly hemodialysis (HD) patients but diagnosing it using the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria requires specialized equipment (DXA, BIA, MRI, CT) and functional tests that are often unavailable in routine or low-resource HD units. Malnutrition and sarcopenia are closely linked in chronic kidney disease (CKD), suggesting that nutritional parameters might serve as surrogate markers. This study aimed to develop a simple sarcopenia index derived from easily accessible anthropometric and nutritional variables to predict EWGSOP2-defined sarcopenia in very elderly HD patients.

**Methods:** A retrospective study was conducted across three outpatient HD units and one hospital in Spain (Fundación Renal Íñigo Álvarez de Toledo) in February 2019. Sixty patients aged 75–95 years on chronic HD for >3 months were included. EWGSOP2 criteria were assessed: (1) probability—hand grip strength (cutoffs: <27 kg men, <16 kg women); (2) confirmation—appendicular skeletal muscle mass by BIA (cutoffs: <20 kg men, <15 kg women); (3) severity—gait speed <0.8 m/s. Nutritional status was evaluated using the Malnutrition-Inflammation Score (MIS), anthropometrics (BMI, brachial circumference, waist-to-hip ratio, skin folds), laboratory values (albumin, cholesterol, phosphate, lymphocytes, 25OH vitamin D, protein catabolism rate), and body composition by BIA. Binomial logistic regression identified the combination of parameters best predicting moderate and severe sarcopenia; performance was assessed by AUC of ROC curves.

**Key Results:** Moderate sarcopenia was present in 30% of normonourished and 50% of malnourished patients; severe sarcopenia in 20% of normonourished and 40% of malnourished patients. Nutritional parameters did not significantly correlate with the suspicion (strength loss) or confirmation (muscle mass loss) of sarcopenia individually, but severe sarcopenia (all three criteria) correlated with malnutrition parameters. The EHSI-M formula (3.0055 + 1.2218[gender] − 0.1358[age] + 0.5977[albumin] + 0.7246[phosphate] + 0.0202[cholesterol]) predicted moderate sarcopenia with AUC 0.80, specificity 87%, sensitivity 61%, and precision 0.7119 at a cutoff of 0.745. The EHSI-S formula (12.3261 − 1.8643[gender] − 0.1830[age] − 0.0430[MIS] + 0.257[cholesterol] + 1.1139[lymphocytes] + 1.1987[subscapular fold]) predicted severe sarcopenia with AUC 0.866, specificity 94%, sensitivity 76%, and precision 0.815 at a cutoff of 0.71.

**Clinical Implications:** The EHSI provides a practical, low-cost tool for identifying sarcopenia in elderly HD patients using routine clinical and laboratory data, potentially enabling earlier nutritional and exercise interventions. The authors caution that protein restriction (0.55–0.6 g/kg/day) recommended for pre-dialysis CKD may exacerbate sarcopenia in elderly patients, and suggest individualized assessment of malnutrition/sarcopenia risk. Limitations include the small sample size (n=60), lack of external validation, use of BIA rather than gold-standard DXA/MRI/CT, and the single-center retrospective design. The formulas are provided for prospective testing across diverse populations.