Hidden Muscle Crisis: Over Half of Dialysis Patients Show Sarcopenia Risk in Landmark Study

More than half of patients on maintenance haemodialysis may be living with sarcopenia, and nearly one in three shows the dangerous combination of malnutrition and muscle wasting simultaneously, according to one of the largest screening studies of its kind ever conducted. The findings, drawn from 3,722 dialysis patients across 40 clinics in 33 cities in Saudi Arabia, reveal a burden of nutritional and muscle disease that far exceeds global averages and expose a critical blind spot in how kidney care is currently delivered. The research, published in the Journal of Cachexia, Sarcopenia and Muscle as part of the Project Muscle initiative, is the first large-scale, multicentre study to characterise malnutrition and sarcopenia risk in a Saudi or wider Middle Eastern dialysis population using standardised, guideline-based screening tools.

Chronic kidney disease affects roughly ten per cent of the global population, and in Saudi Arabia an estimated 4.76 per cent of adults live with the condition. By the end of 2020, more than 20,000 Saudi patients had reached end-stage kidney disease and were dependent on dialysis to survive. This population is uniquely vulnerable to a cluster of interlinked nutritional syndromes, including malnutrition, cachexia, sarcopenia and frailty, along with subcategories such as protein-energy wasting and sarcopenic obesity. The reasons are multifactorial: uremic toxins accumulating in the blood, chronic metabolic acidosis, persistent low-grade inflammation, the dialysis procedure itself stripping amino acids from the circulation, physical inactivity, and comorbidities such as diabetes and cardiovascular disease all conspire to erode muscle and nutritional reserves. These conditions worsen clinical outcomes and degrade quality of life, yet until now, reliable national prevalence data for Saudi dialysis patients simply did not exist.

The study team, working with Diaverum Saudi Arabia, the largest independent kidney care provider in the Kingdom serving approximately a quarter of the dialysis population, screened 4,330 adults undergoing maintenance haemodialysis between June and August 2024. After applying exclusion criteria for pregnancy and severe physical or cognitive impairment, 3,722 patients entered the final analysis. The cohort was relatively young by dialysis standards, with an average age of 53.6 years, and 56.8 per cent were male. Nearly half had a history of diabetes, and 35 per cent carried high or very high comorbidity burden on the Charlson comorbidity index. Most patients dialysed through an autologous arteriovenous fistula and received high-flux haemodialysis.

What makes the study methodologically notable is the rigour applied to standardisation. Fifty-five clinical dietitians across the 40 sites collected data following a written standardised operating procedure after completing a structured six-day training programme covering renal nutrition, measurement protocols and data entry. Identical stadiometers and weighing scales from the same manufacturer were installed in every clinic, and all patient heights and weights were remeasured, with dietitian assessments cross-checked by treating physicians. The protocol was piloted in 392 patients across three sites before the main study, and a centralised electronic data platform with weekly central review and validation reports minimised measurement variability across the three-month collection window.

Malnutrition was assessed using the malnutrition-inflammation score, a validated composite tool that combines subjective global assessment items with comorbidity data, anthropometrics and inflammatory biomarkers including serum albumin and total iron-binding capacity. A score above five indicates high nutritional risk and has been linked to significantly elevated one-year mortality. Sarcopenia risk was screened using the SARC-F questionnaire, which probes strength, assistance with walking, rising from a chair, climbing stairs and falls, combined with calf circumference as a proxy for skeletal muscle mass. The composite SARC-CalF tool was calculated both with raw calf circumference and with values adjusted for body mass index and oedema, the latter subtracting between three and twelve centimetres depending on obesity class and small corrections for fluid retention.

The headline results are stark. Using the malnutrition-inflammation score, 44.5 per cent of patients, or 1,657 individuals, were classified at high nutritional risk. Using the SARC-CalF criteria with adjusted calf circumference, 53.1 per cent, or 1,978 patients, met criteria for sarcopenia risk. The overlap was the most striking finding: 1,175 patients, 31.6 per cent of the cohort, carried both malnutrition and sarcopenia simultaneously, making this the largest single disease subgroup after those free of both conditions. A further 13 per cent had malnutrition without sarcopenia, while 21.6 per cent, 803 patients, showed sarcopenia risk despite passing the nutritional screen. Within that latter group, 285 patients, 7.7 per cent, had sarcopenic obesity, where excess adiposity masks underlying muscle loss.

That 21.6 per cent figure represents what the researchers describe as a potentially clinically important blind spot. In dialysis populations, higher adiposity or a stable body mass index can conceal progressive muscle wasting, meaning conventional reliance on weight-based screening alone is inadequate. The combined malnutrition-plus-sarcopenia group told an equally sobering story: compared with patients free of both conditions, these individuals were significantly older, more likely to be female and diabetic, had longer dialysis vintage, lower functional status on the Karnofsky scale, and dramatically elevated fall risk. Among patients in this combined group classified at high risk of falls on the Morse fall scale, 61.1 per cent fell into the malnutrition-plus-sarcopenia category, all while carrying an average body mass index of 25.42, technically borderline overweight. Their biochemistry told the same story, with lower albumin, lower total iron-binding capacity, lower creatinine and reduced protein catabolic rates pointing to depleted muscle and inadequate dietary protein intake.

Multivariate logistic regression, corrected for multiple comparisons using the Benjamini-Hochberg false discovery rate, identified the independent drivers of each condition. For malnutrition risk, these were lower body mass index, higher comorbidity burden, longer duration on dialysis, shorter average weekly treatment time, lower serum creatinine and higher triglycerides. For sarcopenia, the independent predictors were older age, higher comorbidity index, longer time on dialysis, lower serum creatinine and higher triglycerides. Notably, sarcopenia risk proved independent of body mass index, reinforcing the argument that muscle status must be assessed directly rather than inferred from weight. The authors suggest that promoting arteriovenous fistula use, particularly in younger patients, and adherence to prescribed treatment times may carry value beyond dialysis adequacy, potentially protecting against sarcopenia and functional decline. Serum creatinine, they note, may merit exploration as a low-cost proxy for muscle mass in diagnosis.

The prevalence figures sit well above global benchmarks. Recent systematic reviews of dialysis populations have reported pooled sarcopenia prevalences of 25.6 per cent and between 25.9 and 34.6 per cent, and a global meta-analysis found muscle weakness in 50 per cent of dialysis patients compared with 19.6 per cent of those not yet on dialysis. The Saudi figures for SARC-F and SARC-CalF with unadjusted calf circumference aligned more closely with these international averages, but the adjusted-circumference estimate of 53 per cent exceeded them substantially, and 74.7 per cent of patients showed severely low adjusted calf circumference values. The authors caution that the cut-off points, derived from United States NHANES data, may lack accuracy for a younger and more overweight Saudi population, and call for local validation studies comparing the tool against gold-standard body composition techniques such as magnetic resonance imaging. The malnutrition figure of 44.5 per cent, by contrast, is consistent with earlier smaller Saudi studies reporting prevalences of 48.7 to 55 per cent.

The clinical implications are considerable. The profile of the combined malnutrition-sarcopenia group, with reduced functional capacity, adverse inflammatory biomarkers and reduced protein intake, closely mirrors established phenotypic criteria for cachexia, and previous studies have shown that the combination independently increases mortality risk in haemodialysis patients. These patients, the researchers argue, are likely to benefit most from targeted, multidisciplinary interventions combining nutritional support, resistance exercise and management of inflammation and comorbidity, an approach now being tested in clinical trials for cachexia across chronic conditions. Crucially, this high-risk phenotype would be systematically missed by body mass index and weight-based screening alone, strengthening the case for routine, multitool nutritional and muscle assessment as standard practice in dialysis units. The study does carry limitations: screening tools cannot substitute for gold-standard body composition or functional assessments, calf circumference cut-offs require local validation, and individual-level physical activity data were not collected, leaving room for residual confounding. Even so, as the first large-scale, multicentre characterisation of these syndromes in the region, the work establishes a foundation for the detailed anthropometric, body composition and biomarker analyses now underway within Project Muscle, and points towards a future where every dialysis patient is screened for the silent loss of muscle that conventional checks overlook.

Subject of Research: Prevalence and overlap of malnutrition, sarcopenia and related nutritional syndromes in a large haemodialysis population

Article Title: Prevalence and Overlap of Malnutrition, Sarcopenia and Related Nutritional Syndromes in a Large Haemodialysis Population

Article References: Prevalence and Overlap of Malnutrition, Sarcopenia and Related Nutritional Syndromes in a Large Haemodialysis Population. (n.d.). https://doi.org/10.1002/jcsm.70386

Image Credits: AI Generated

DOI: 10.1002/jcsm.70386

Keywords: haemodialysis, sarcopenia, malnutrition, chronic kidney disease, protein-energy wasting, sarcopenic obesity, cachexia, SARC-CalF, malnutrition-inflammation score, calf circumference, Saudi Arabia, nutritional screening