Is Hemodialysis Patient Survival Dependent upon Small Solute Clearance (Kt/V)?: If So How Can Kt/V be Adjusted to Prevent Under Dialysis in Vulnerable Groups?

Adjusting dialysis dose (Kt) scaled to Body Surface Area (BSA) could be a more logical approach

The dialysis dose, quantified as Kt, is conventionally scaled to the urea distribution volume (V) to calculate the Kt/V ratio as an indicator of dialysis adequacy. However, the body surface area (BSA) is recognized as a more accurate reflection of metabolic activity compared to V. This study presents evidence supporting the enhanced efficacy of the Kt/BSA ratio as an indicator of hemodialysis adequacy. The study population comprised 211 individuals undergoing hemodialysis, all of whom had Kt/V values determined. Body composition was assessed using bioimpedance techniques, and BSA was calculated employing the DuBois and DuBois formula. The ratio of V/BSA served as the conversion factor to derive Kt/BSA from the standard Kt/V. Participants were categorized by gender, and a comparative analysis was performed on dialysis-related parameters alongside body composition indicators. Concurrently, linear regression analysis was applied to Kt/V and Kt/BSA, as well as to pairs of V and BSA, to elucidate the relationships among these variables. The average Kt/V ratio was 1.50 with a standard deviation of 0.28. The Kt/V ratio was significantly higher in women (P < 0.01). Conversely, the Kt value, when not adjusted for body size, was significantly lower in women (P < 0.01). Upon scaling Kt to BSA to calculate Kt/BSA, the gender difference in dialysis dose adequacy was no longer statistically significant (P = 0.06). Men exhibited a significantly higher mean V/BSA ratio. Additionally, women had a slightly higher mean percentage of fat mass (P < 0.01). In contrast, women had a lower mean percentage of muscle mass (P < 0.01). Our findings suggest that the Kt/V ratio may underestimate the required hemodialysis dose for women. There was no gender difference when Kt scaling to BSA. Consequently, the Kt/BSA ratio, which accounts for body surface area, may play a significant role in more accurately scaling the hemodialysis dose.

Age, Gender and Diabetes as Risk Factors for Early Mortality in Dialysis Patients: A Systematic Review

Objective: To study the impact of age, gender, and presence of diabetes (any type) on the risk of early deaths (180-day mortality) in patients starting long-term hemodialysis (HD) therapy.Design: Systematic review of the literature.Setting: Out-patient (non-hospitalized), community-based HD therapy world-wide.Participants: Patients with advanced chronic kidney disease (CKD) starting long-term HD treatment for end-stage renal disease (ESRD).Methods: Medline and EMBASE were searched for studies published between 1/1/1985 and 12/31/2017. Observational studies involving adult subjects commencing HD were included. Data extracted included population characteristics and settings. In addition, patient or treatment related factors studied with reference to their relationship with the risk of early mortality were documented. The Quality in Prognosis Studies tool was used to assess risk of bias in individual studies. Findings were summarized, and a narrative account was drawn.Results: Included were 26 studies (combined population 1,098,769; representing 287,085 person-years of observation for early mortality). There were 17 cohort and 9 case-control studies. Risk of bias was low in 13 and high in a further 13 studies. Patients who died in the early period were older than those who survived. Mortality rates increased with advancing age. Female gender was associated with slightly increased early mortality rates in larger and higher quality studies. The available data showed conflicting results in relation to the association of diabetes and risk of early mortality.Conclusions: This systematic review evaluated the impact of key demographic and co-morbid factors on risk of early mortality in patients starting maintenance HD. The information could help in delivering more tailored prognostic information and planning of future interventions.

A swan song for Kt/Vurea

Dialyzer clearance of urea multiplied by dialysis time and normalized for urea distribution volume (Kt/V_urea or simply Kt/V) has been used as an index of dialysis adequacy since more than 30 years. This article reviews the flaws of Kt/V, starting with a lack of proof of concept in three randomized controlled hard outcome trials (RCTs), and continuing with a long list of conditions where the concept of Kt/V was shown to be flawed. This information leaves little room for any conclusion other than that Kt/V, as an indicator of dialysis adequacy, is obsolete. The dialysis patient might benefit more if, instead, the nephrology community concentrates in the future on pursuing the optimal dialysis dose that conforms with adequate quality of life and on factors that are likely to affect outcomes more than Kt/V. These include residual renal function, volume status, dialysis length, ultrafiltration rate, the number of intra-dialytic hypotensive episodes, interdialytic blood pressure, serum potassium and phosphate, serum albumin, and C reactive protein.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.