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

The research, published in the open-access journal Nursing Open, took an unusual analytical approach: instead of studying patients as single units, the investigators examined every recorded haemodialysis session over a full year, from January to December 2021, in patients treated through tunnelled catheters within a national renal foundation network in Spain. The result was a dataset of 40,193 sessions from 743 patients, of which 987 sessions, or 2.5 percent, met the study’s operational definition of intradialytic catheter dysfunction. That definition was grounded in internationally recognised KDOQI thresholds: a machine-registered dysfunction flag appeared whenever blood flow fell below 300 millilitres per minute while arterial pre-pump pressure dropped below minus 250 millimetres of mercury, venous return pressure rose above plus 250 millimetres of mercury, or both, at the start of the session or at the 60-minute mark. Nursing staff then verified each flagged event in the electronic dialysis record system.

The cohort itself was clinically striking. The patients averaged 68.4 years of age and carried a heavy burden of chronic disease: 84.5 percent had arterial hypertension, 60.1 percent had cardiovascular disease, and nearly half lived with diabetes. Diabetic nephropathy was the leading cause of kidney failure, accounting for 34.3 percent of cases. Notably, women made up 63.7 percent of the cohort, a marked contrast with national registry data in which men typically account for roughly two-thirds of the haemodialysis population, a difference the authors attribute to the particular clinical profile of patients who end up dialysing through tunnelled catheters rather than through surgically created arteriovenous fistulas.

When the researchers compared dysfunctional sessions with smooth-running ones, the haemodynamic signatures diverged sharply, exactly as the outcome definition would predict. Sessions with dysfunction began with a mean blood flow of 257.9 millilitres per minute versus 350.7 in healthy sessions, and by the 60-minute mark the gap persisted, with flows of 256 versus 358.3. Arterial pressures plunged dramatically deeper into negative territory, averaging minus 215.2 millimetres of mercury across dysfunctional sessions compared with minus 172.2 in uneventful ones. Total blood volume processed fell from 75.6 litres to 56.2, and the final Kt, the routinely recorded marker of the dialysis dose actually delivered, dropped from 48.2 litres to 39.1. In plain terms, a failing catheter deprived patients of nearly a fifth of the intended cleansing capacity of each session.

Beyond the intradialytic pressure readings themselves, which the authors are careful to frame as manifestations of dysfunction rather than causes of it, the analysis identified baseline characteristics that clustered with failing sessions. Catheters placed in the left internal jugular vein showed a dysfunction rate of 5.1 percent, dramatically higher than the 0.7 percent observed with the right internal jugular vein, the most popular insertion site in the cohort. Femoral placement, though rare, performed poorly, with the right femoral vein showing dysfunction in 6.3 percent of sessions, consistent with earlier evidence that femoral and subclavian sites carry higher thrombotic and mechanical risks. Comorbidities also left fingerprints: diabetes, cardiopathy, peripheral arterial disease, prior stroke, and a history of malignancy were all significantly more frequent in dysfunctional sessions, as was systemic anticoagulant therapy, though the authors caution this may reflect the vascular risk profile of the patients rather than a drug effect.

Perhaps the most technically revealing part of the study was its stratification of dysfunction events into arterial and venous types. Of the 1,481 recorded events, 1,346 were arterial and 135 were venous, and the two behaved like distinct clinical entities. Arterial events featured severely negative pre-pump pressures, averaging minus 221.9 millimetres of mercury, signalling that the catheter was struggling to draw blood in, and were more common in older patients with hypertension, cerebrovascular disease, and prior SARS-CoV-2 infection. Venous events, by contrast, showed soaring return pressures averaging 220.4 millimetres of mercury, indicating obstruction on the outflow side, and occurred disproportionately in men, in patients with peripheral arterial disease, tumours, previous kidney transplants, and those on anticoagulants. Venous events also produced significantly lower final Kt values, suggesting the outflow type of failure may be particularly punishing for dialysis adequacy.

Two management variables, line reversal and 5 percent sodium heparin locking solution, appeared far more often in dysfunctional sessions, with line reversal documented in 3.5 percent of sessions without dysfunction versus an elevated share within dysfunctional ones, and 5 percent heparin locks showing a 4.3 percent dysfunction rate against 2 percent for the standard 1 percent heparin. But the researchers explicitly warn against reading these numbers causally. In routine practice, clinicians reverse catheter lines and escalate locking solutions precisely because a catheter is already underperforming, so the association plausibly reflects a rescue response rather than a culprit. This principle of reverse causality and confounding by indication permeates the entire analysis and is one of the paper’s most intellectually honest contributions to a field where such distinctions are often blurred.

The pharmacological findings followed the same cautious logic. Overall, systemic antiplatelet therapy showed no significant association with dysfunction when analysed as a single binary variable, yet drug-specific comparisons revealed significant heterogeneity, with acetylsalicylic acid regimens, clopidogrel, prasugrel, and dipyridamole each showing different dysfunction frequencies. Among anticoagulants, enoxaparin and especially tinzaparin were the agents most frequently associated with dysfunction events, while combined regimens such as enoxaparin with warfarin appeared far less often in failing sessions. The authors interpret these patterns as exploratory and hypothesis-generating, likely shaped by differences in patient indication and underlying vascular disease rather than by direct pharmacological effects on catheter patency, and they point to prior trials of agents like recombinant tissue plasminogen activator and taurolidine-based locks as avenues where randomised evidence has begun to clarify what observational data cannot.

Dialysis efficacy emerged as a second major storyline. Using sex-specific operational Kt thresholds, the researchers classified 24.7 percent of sessions as low efficacy, 20.8 percent as normal, and 52.6 percent as optimal. The sex split was dramatic: 41.4 percent of male patients’ sessions fell into the low-Kt category, while 65.6 percent of women’s sessions reached the optimal range, a highly significant difference partly attributable to the fact that Kt depends on body size, and men on average process more blood volume through larger bodies. Because Kt was measured session-by-session through ionic dialysance rather than sampled sporadically, the study demonstrates how continuous, per-session adequacy monitoring can flag patients at risk of chronic under-dialysis, particularly catheter-dependent men, long before cumulative toxin buildup becomes clinically apparent.

The study’s limitations are considerable and openly acknowledged. The analysis was univariate and did not adjust for the fact that dozens of sessions belonged to the same patient, which may have inflated statistical significance. Being retrospective and built on routine electronic records, it could not capture insertion technique, operator experience, catheter tip design or position, or fibrin sheath formation, all recognised determinants of catheter survival, and all data came from a single institutional network, limiting generalisability. Still, the practical message is clear and actionable: continuous vigilance over blood flows, line pressures, and pressure trajectories during every dialysis session can catch failing catheters early, and the distinct arterial-versus-venous signatures described here give nurses and nephrologists a framework for interpreting what the machine alarms are actually telling them. The authors call for adjusted analytical studies, trials of locking strategies and anticoagulation protocols, and exploration of nursing-led interventions, all aimed at turning a descriptive atlas of catheter failure into genuine prediction and prevention.

Subject of Research: Clinical and technical factors associated with tunnelled central venous catheter dysfunction in haemodialysis patients

Article Title: Clinical and Technical Factors Associated With Tunnelled Central Venous Catheter Dysfunction in Haemodialysis: A Multicentre Session‐Level Retrospective Study

Article References: Gimeno Hernán, V., Perez Ingidua, C., Rivas Paterna, A. B., Moreno, G., Vicente‐Galán, M. J., Orgaz‐Rivas, E., Meneses‐Monroy, A., & Ortuño‐Soriano, I. (2026). Clinical and Technical Factors Associated With Tunnelled Central Venous Catheter Dysfunction in Haemodialysis: A Multicentre Session‐Level Retrospective Study. Nursing Open, 13(9), Article e70758. https://doi.org/10.1002/nop2.70758

Image Credits: AI Generated

DOI: 10.1002/nop2.70758

Keywords: haemodialysis, central venous catheter, catheter dysfunction, dialysis adequacy, Kt, vascular access, anticoagulation, antiplatelet therapy, nephrology, internal jugular vein, retrospective study, nursing