Association of achieved dialysis dose with mortality in the hemodialysis study: an example of "dose-targeting bias"

Prescribing and monitoring hemodialysis in a 3-4 x/week setting

The basics of targeting, writing, adjusting, and monitoring a hemodialysis prescription are reviewed for patients being dialyzed 3 or 4 times a week. K/DOQI 2006 adequacy guidelines and practice recommendations are reviewed, and a practical method using a variety of nomograms is suggested to monitor and adjust the desired level of Kt/V.

Adipokines, linking adipocytes and vascular function in hemodialyzed patients, may also be possibly related to CD146, a novel adhesion molecule

Possible correlations between adiponectin, leptin, CD146, a novel adhesion molecule localized at the endothelial junction, and other markers of endothelial cell injury, von Willebrand factor, thrombomodulin, vascular cell adhesion molecule, and intracellular adhesion molecule, and markers of inflammation, tumor necrosis factor-alpha, interleukin-6, and high-sensitivity C-reactive protein in nondiabetic hemodialyzed patients with and without coronary artery disease were studied. Markers of endothelial dysfunction were elevated in hemodialyzed patients, predominantly with coronary artery disease. In multivariate analysis, kinetic urea modeling and plasminogen activator inhibitor-1 remained the only positive predictors of adiponectin. In multivariate analysis, predictors of leptin were triglycerides, tissue plasminogen activator, CD146, and coronary artery disease. In multivariate analysis, predictors of CD146 were age, hemoglobin, and adiponectin. Elevated adiponectin correlated to CD146 may be the expression of a counterregulatory response aimed at mitigating the consequences in endothelial damage and increased cardiovascular risk in renal failure. The data provide further support for a link between adipocytokines, endothelial dysfunction, cardiovascular risk, and renal failure.

The Basic, Quantifiable Parameter of Dialysis Prescription Is Kt/V Urea; Treatment Time Is Determined by the Ultrafiltration Requirement; All Three Parameters Are of Equal Importance

There have only been two randomized controlled trials studying outcome as a function of dose in hemodialysis (HD). The first was the National Cooperative Dialysis Study which showed that adequate dialysis was achieved with spKt/V >1.00. The second study was HEMO which was originally designed to study spKt/V 1.2 compared to spKt/V 1.45. Unfortunately by the time HEMO was started, observational studies (OS) had convinced the nephrology community that the minimum adequate dose of spKt/V was 1.40, so the lower target was increased to 1.4 and the upper target to 1.7. The study showed no difference in outcome, although OS have now demonstrated that outcome improves up to spKt/v 2.00. Analysis of HEMO as treated showed that there is a fundamental flaw in dose-targeted OS in that the optimal dose always, but spuriously, increases as the studied dose increases due to dose-targeting bias. Similar flaws exist in the association of treatment time to outcome.

Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate

BACKGROUND

Glomerular filtration rate (GFR) estimates facilitate detection of chronic kidney disease but require calibration of the serum creatinine assay to the laboratory that developed the equation. The 4-variable equation from the Modification of Diet in Renal Disease (MDRD) Study has been reexpressed for use with a standardized assay.

OBJECTIVE

To describe the performance of the revised 4-variable MDRD Study equation and compare it with the performance of the 6-variable MDRD Study and Cockcroft-Gault equations.

DESIGN

Comparison of estimated and measured GFR.

SETTING

15 clinical centers participating in a randomized, controlled trial.

PATIENTS

1628 patients with chronic kidney disease participating in the MDRD Study.

MEASUREMENTS

Serum creatinine levels were calibrated to an assay traceable to isotope-dilution mass spectrometry. Glomerular filtration rate was measured as urinary clearance of 125I-iothalamate.

RESULTS

Mean measured GFR was 39.8 mL/min per 1.73 m2 (SD, 21.2). Accuracy and precision of the revised 4-variable equation were similar to those of the original 6-variable equation and better than in the Cockcroft-Gault equation, even when the latter was corrected for bias, with 90%, 91%, 60%, and 83% of estimates within 30% of measured GFR, respectively. Differences between measured and estimated GFR were greater for all equations when the estimated GFR was 60 mL/min per 1.73 m2 or greater.

LIMITATIONS

The MDRD Study included few patients with a GFR greater than 90 mL/min per 1.73 m2. Equations were not compared in a separate study sample.

CONCLUSIONS

The 4-variable MDRD Study equation provides reasonably accurate GFR estimates in patients with chronic kidney disease and a measured GFR of less than 90 mL/min per 1.73 m2. By using the reexpressed MDRD Study equation with the standardized serum creatinine assay, clinical laboratories can report more accurate GFR estimates.

Effect of intravenous iron sucrose in peritoneal dialysis patients who receive erythropoiesis-stimulating agents for anemia: a randomized, controlled trial

Although iron therapy is essential to optimize use of erythropoiesis-stimulating agents (ESA), randomized, controlled trials have heretofore been unavailable to evaluate reliably the efficacy of intravenous iron as an adjuvant to ESA treatment in peritoneal dialysis (PD) patients. In a multicenter trial, patients who had anemia, PD-dependent chronic kidney disease, stable ESA therapy, and a broad range of iron status (ferritin < or = 500 ng/ml, transferrin saturation < or = 25%) were randomly assigned to receive either 1 g of iron sucrose intravenously in three divided doses (300 mg over 1.5 h on days 1 and 15, 400 mg over 2.5 h on day 29) or no supplemental iron. No serious adverse drug events occurred after intravenous iron administration. The primary end point, peak hemoglobin increase, was higher (1.3 +/- 1.1 versus 0.7 +/- 1.1, mean +/- SD; P = 0.0028), and anemia intervention (transfusion, increase in ESA dose, or intravenous iron therapy not called for in protocol) occurred later (P = 0.0137) and less often in intravenous iron-treated patients compared with untreated control subjects (one of 66 [1.3%] versus five of 30 [16.7%]). Among patients who did not require intervention, iron-treated patients showed a calculated net ESA dose decrease compared with untreated control subjects. Baseline iron status did not predict responsiveness to intravenous iron therapy. Intravenous iron sucrose is an effective adjunct to ESA therapy in anemic patients with PD-dependent chronic kidney disease and is administered safely as 300 mg over 1.5 h or 400 mg over 2.5 h. Evidence of iron deficiency at baseline is not required to demonstrate intravenous iron efficacy.