The latest issue of Kidney International (KI) includes an article entitled "Regression of left ventricular hypertrophy after conversion to nocturnal hemodialysis." Abstract from KI.

April 11, 2002 - The February 2002 issue of Artificial Organs contains an abstract that supports a new index for measuring hemodialysis adequacy, the Hemodialysis Product (HDP).

The HDP index does not measure any blood work value, but instead simply uses:

• the number of dialysis sessions per week and
• the number of hours per session.

An HDP above 70 has been proposed as a new target for hemodialysis adequacy. A typical hemodialysis patient in the United States has an HDP equal to 36 (three four-hour sessions per week).

Here is the abstract of "Alternative Timeframes for Hemodialysis" from Artificial Organs. It makes a case for replacing the standard maintenance hemodialysis schedule (alternate days with sessions lasting 3 to 5 h) with daily hemodialysis or longer sessions.

March 26, 2002 - The latest issue of the Journal of the American Society of Nephrology (JASN) has an article from the Kidney Epidemiology and Cost Center (web site) on dialysis dose, body mass index, and patient survival.

Here is the abstract of "Dialysis Dose and Body Mass Index Are Strongly Associated with Survival in Hemodialysis Patients" - from April 2002 JASN.

Conclusion: "Patients treated with URR >75% had a substantially lower relative risk than patients treated with URR 70 to 75%. It is concluded that a higher dialysis dose, substantially above the Dialysis Outcomes Quality Initiative guidelines (URR >65%), is a strong predictor of lower patient mortality for patients in all body-size groups. Further reductions in mortality might be possible with increased HD dose."

Here is a comparison of URR and Kt/V from the NIDDK web site.

In June 2001, the ADEMEX (Adequacy of Peritoneal Dialysis in Mexico) study was presented at the International Society of Peritoneal Dialysis meeting today in Montreal. The results showed that increasing the dose of CAPD, as measured by Kt/V, had no effect on patient survival. Here is the press release from Baxter on the study and an excerpt of the press release:

"This study provides the first evidence showing that pressing for higher levels of small solute clearance -- which is difficult for so many (PD) patients -- yields no difference in patient survival compared with the ranges of clearance more easily achieved during real-world practice."

• Kt/V only assesses the removal of a water-soluble compound from the body water through mostly hydrophilic membranes to the dialysate water
  
• the small size of urea means that convective and/or diffusive transfer through a given semipermeable membrane is unlikely to be representative of larger molecules
  
• urea kinetics are poorly representative of the removal of small protein-bound molecules and intracellular solutes with cell membrane-limited clearance
  
• Kt/V concept has been developed in a specific population

February 12, 2002 - The January issue of the journal Dialysis and Transplantation (D&T) has an article by two prominent nephrologists that touts a new index for measuring hemodialysis adequacy, the Hemodialysis Product (HDP).

Drs. Belding Scribner and Dimitrios Oreopoulos describe the current standard, Kt/V, as flawed as it fosters short dialysis sessions and does not address the importance of removing middle molecues during hemodialysis. They state there is irrefutable support for the conclusion that the adequate removal of middle molecues correlates better with survival and well-being than the clearance of the smaller urea molecue (which is used for Kt/V).

The full text D&T article, entitled "The Hemodialysis Product: A Better Index of Dialysis Adequacy than Kt/V", is available on-line as a PDF file.

The HDP index is somewhat unusual in that it does not measure any blood work value, but instead simply uses:

• the number of dialysis sessions per week and
• the number of hours per session.

A typical hemodialysis patient in the United States has an HDP equal to 36 (three four-hour sessions per week). Drs. Scribner and Oreopoulos conclude that an HPD of 36 results in inadequate blood pressure control and malnourishment for hemodialysis patients. The paper suggests that patients regain a sense of well-being and have better controlled blood pressure with an HDP above 70.

An HDP of 72 could be achieved for a typical patient by dialyzing six times a week for two hours per session. This would be the same number of hours on the dialysis machine per week (12), but would double the HDP value from 36 to 72.

By emphasizing the value of more frequent hemodialysis treatments, the HDP index correlates better to blood pressure control than the Kt/V index. HDP also correlates better to total solute removal than Kt/V. Hemodialysis is most efficient at solute removal at the beginning of the treatment due to the higher diffusion gradients that exist at that time. Clearance (clearing a volume of blood of a solute), which is the "K" in Kt/V, is essentially constant throughout the hemodialysis treatment.

The authors state that "for reasons unknown, these remarkable (HDP and more frequent dialysis) results have been largely ignored by the U.S. hemodialysis community, which still bases its definition of minimum adequate dialysis on a Kt/V=1.2 per dialysis 3x/week."

This may be because Medicare, the largest payer for hemodialysis services, provides reimbursement for only three hemodialysis sessions per week under the current reimbursement/composite rate system (Medicare Renal Dialysis Facility Manual - Coverage of Services). (link is no longer available) Until this policy is changed, the adoption of this new therapy approach is economically unfeasible for most dialysis centers and patients.

Is this an example of Medicare's reimbursement/composite rate system leading to poor medical outcomes and inferior patient care? How big a role is Medicare's reimbursement/composite rate system playing in the high incidences of malnutrition (link is no longer available), cardiovascular disease, and depression seen in dialysis patients?

In June 2001, the ADEMEX (Adequacy of Peritoneal Dialysis in Mexico) study was presented at the International Society of Peritoneal Dialysis meeting today in Montreal. The results showed that increasing the dose of CAPD, as measured by Kt/V, had no effect on patient survival. Here is the press release from Baxter on the study and an excerpt of the press release:

"This study provides the first evidence showing that pressing for higher levels of small solute clearance -- which is difficult for so many (PD) patients -- yields no difference in patient survival compared with the ranges of clearance more easily achieved during real-world practice."

"The Next Step from High-Flux Dialysis: Application of Sorbent Technology" - abstract from Blood Purification

RenalTech's BetaSorb utilizes a new adsorptive polymer to remove more "middle molecues" during dialysis. These middle molecue substances include beta-2 microglobulin, granulocyte inhibitory protein, parathyroid hormone, and Complement Factor D. Dialyzers on the market today remove only 10-40% of beta-2 microglobulin, which causes destructive arthritis and carpal tunnel syndrome. RenalTech has been able to demonstrate over 99% removal of beta-2 during in vitro testing.

Here is the RenalTech web site.

Finally, here is the RenalWEB Topic Page on Hemodialysis Adequacy.