The prevalence of Sarcopenia varies between 1.5% and 68% among patients with chronic kidney disease (CKD). This wide range is due to the different diagnostic tools and the cut-off points used. Early diagnosis and intervention of sarcopenia are essential because of its association with poorer quality of life (QoL), higher hospitalization rates, and adverse events. The "European Working Group on Sarcopenia in Older People (EWGSOP2)" consensus review suggests ultrasound as an emerging tool to quantify muscle mass. Our objective is to describe the prevalence of sarcopenia risk in peritoneal dialysis (PD) and the utility of ultrasound in our setting. We conducted an observational study in prevalent PD patients at the Puerta de Hierro University Hospital between January and October 2023. Clinical, efficacy, analytical and nutritional parameters were collected, along with functional performance measured by SPPB, frailty (FRAIL scale), risk of malnutrition (MIS scale), bioimpedance (BCM) and estimation of appendicular skeletal muscle mass using Lin's formula. Ultrasound measurement of supramuscular fat, Axes (X and Y) and the area of the rectus femoris muscle (RFM) were also included, adjusted for height and body surface area. We classified patients at risk of sarcopenia based on handgrip strength according to EWGSOP2 criteria, adjusted for sex. This study was approved by the Ethics Committee of Puerta de Hierro University Hospital (No. 16/2023). We evaluated 38 patients, with a mean age of 65.4 years (SD 14.9), 65.8% were male. 52.6% had a reduced lean tissue index (LTI) and 23.7% had a reduced fat tissue index (FTI), with a mean phase angle (PA) of 4.5 (SD 1.1). We classified 42.1% as patients at risk of sarcopenia based on handgrip strength. They were older, had more comorbidities, poorer nutrition according to the MIS scale, and showed worse scores on frailty and functional capacity. Similary, they had a lower LTI, lower appendicular skeletal muscle mass, and lower quadriceps muscle thickness (Y axis 8.5 mm (SD 2.4) vs 11.8 mm (SD 3.3) p = 0.002). Patients at risk of sarcopenic had lower phosphorus levels and higher C-reactive protein (CRP) levels. The predictive capacity of ultrasound for classifying patients at risk of sarcopenia was AUC 0.78 (0.64-0.93) for Y Axis, similar to those obtained with the LTI and PA of bioimpedance. Sarcopenia risk is highly prevalent in PD and is related to age, comorbidity, malnutrition and inflammation in patients. Ultrasound is an accessible, safe, low-cost and easy-to-use tool at the bedside. This method helps us to quantify muscle mass and assess its quality. We propose the thickness of the RFM (Y axis) as the best complementary parameter given its good correlation with bioimpedance and its diagnostic value for sarcopenic risk. Our experience will serve as a basis for future studies that allow us to define specific cut-off points in PD and design monitoring and intervention protocols.

Body mass index inadequately reflects body composition in advanced chronic kidney disease (CKD). Lean tissue index (LTI), a marker of muscle mass, predicts mortality in CKD, but its association with disease progression is uncertain. We evaluated whether age- and sex-adjusted LTI measured by bioelectrical impedance analysis (BIA) predicts progression to kidney replacement therapy (KRT) and mortality in stage 4 to 5 CKD. This retrospective cohort study included 145 adults with stage 4 to 5 CKD referred to an advanced CKD outpatient clinic. Body composition was assessed by BIA within 6 mo of referral. Low LTI was defined as values below the 10th percentile using age- and sex-specific reference standards. Associations with outcomes were analyzed using Kaplan-Meier estimates, multivariable Cox regression, and competing-risk analysis. Mean age was 72 ± 11.8 y, mean estimated glomerular filtration rate was 20.4 ± 4.7 mL/min/1.73 m², and 13.1% had low LTI. During a median follow-up of 28 mo, 49.7% initiated KRT and 37.9% died. Low LTI was associated with poorer renal and overall survival (log-rank P = 0.019 and P = 0.006). In multivariable analysis, low LTI independently predicted progression to KRT (hazard ratio 2.20; 95% confidence interval 1.02-4.75) along with lower estimated glomerular filtration rate and higher albuminuria. After accounting for competing risk of death, the association with KRT was attenuated. Low LTI independently predicted mortality (hazard ratio 4.82; 95% confidence interval 1.84-12.64). Low lean tissue index is associated with mortality and may identify patients at higher risk of CKD progression. Routine body composition assessment may improve risk stratification in advanced CKD.

Background/Objectives: Frailty is increasingly recognized as a major determinant of adverse outcomes in patients receiving peritoneal dialysis (PD), yet it is not routinely incorporated into clinical practice. Because PD relies heavily on patient autonomy and self-management, frailty, sarcopenia, malnutrition, and impaired quality of life may compromise both outcomes and technique retention. This study aimed to describe current clinical practices related to frailty-informed assessment in PD units participating in the GCDP network and to identify barriers to implementing a more comprehensive, patient-centered approach. Methods: We conducted a descriptive, observational, cross-sectional study based on a survey distributed to PD units belonging to the Grupo Centro de Diálisis Peritoneal (GCDP), a collaborative network of 24 hospitals across four autonomous communities in Spain. Physicians and nurses completed the questionnaire between January and February 2025. The survey explored seven domains: use of frailty scales, nutritional screening tools, dynamometry, muscle ultrasound, bioimpedance, quality of life instruments, and digital applications for patient follow-up. Results: Twenty of 24 centers completed the survey. Although all units considered frailty clinically relevant, only 11 assessed it at PD initiation and only 5 performed periodic or systematic re-evaluation. Nutritional screening tools were used in 13 centers, most commonly the Malnutrition Inflammation Score. Twelve centers had a dynamometer, though its use was not standardized. All centers used bioimpedance—primarily for hydration assessment—while muscle ultrasound was rarely applied in scheduled follow-up. Only 7 centers assessed quality of life. The main reported barriers were lack of time in routine practice and the absence of specific guidelines and training. Conclusions: Frailty-related assessment across participating GCDP units remains heterogeneous and incompletely implemented despite broad recognition of its clinical relevance. The identified gaps in standardized protocols, training, and integration of assessment tools highlight priorities for future implementation research aimed at incorporating frailty-informed, patient-centered assessment into routine PD care.