Vascular access thrombosis during recombinant human erythropoietin therapy

Erythropoietin therapy improves graft patency with no increased incidence of thrombosis or thrombophlebitis

BACKGROUND

Recombinant human erythropoietin (rHuEPO) for the treatment of severe anemia in patients with end-stage renal disease (ESRD) is suggested to improve rehabilitation and cognitive function. The criticism is the alleged increase in the failure rate of arteriovenous (AV) access grafts and in the incidence of lower-extremity deep venous thrombophlebitis (DVT). This study addressed the longevity of AV grafts and the incidence of DVT.

STUDY DESIGN

We reviewed 481 consecutive patients with ESRD on dialysis with PTFE access grafts, including 173 consecutive patients who were receiving rHuEPO and 308 who were not. rHuEPO was administered during dialysis titrated against the hematocrit to achieve a level of 33% to 38%. The rHuEPO-ESRD group included 173 patients with a mean age of 58 years, including 54% women; 84% of the grafts were in the upper extremity. In the control group of 308 patients, 57% were women. Diabetes and hypertension were controlled in both groups.

RESULTS

Forty-five of 173 rHuEPO patients (26%) experienced graft thrombosis within 1 year. Among 88 episodes of thrombosis, 14 patients experienced multiple episodes. Primary patency was 8.9 months; secondary patency was 11.2 months. In the control population, 95 of 308 patients (31%) experienced graft thrombosis; 27 patients had multiple episodes. Primary patency was 7.8 months and secondary patencywas 9.8 months. The hematocrit improved from a mean of 23% in the control group to 34% in the treated rHuEPO group. Two patients in the control group and one patient receiving rHuEPO experienced DVT in the lower extremity.

CONCLUSIONS

Primary and secondary AV fistula patency rates were improved by 10% with rHuEPO. rHuEPO did not increase DVT.

Evidence-based recommendations for the clinical use of recombinant human erythropoietin

In an era of increasing scrutiny regarding use of health care resources, it is critical that physicians have rational, evidence-based guidelines for treatment decisions. This review of more than 200 published papers constitutes a comprehensive approach to evaluating the current evidence regarding the clinical use of recombinant human erythropoietin therapy in renal failure patients. After this review, specific recommendations are provided regarding who should receive r-HuEPO; what the target hemoglobin should be; the best route of administration of r-HuEPO; how iron status should be evaluated and managed; and monitoring and follow-up of patients taking r-HuEPO. Throughout the article, areas for important future research are also identified.

Vascular access thrombosis in new hemodialysis patients

This study identifies factors that are associated with the risk of access thrombosis in 267 new hemodialysis patients. There are few longitudinal studies evaluating the risk of access thrombosis despite the need for long-term use of the access for maintenance hemodialysis. We used a prospective design following patients from 26 providers in Renal Network Council #12 (Iowa, Missouri, Kansas, and Nebraska) for 1 year who were starting hemodialysis. There were significant increases in access thrombosis relative risk (RR) associated with the placement of a polytetrafluoroethylene graft compared with patients with the arteriovenous fistula (RR 1.98; 95% confidence interval [CI] = 1.3, 3,01). The probability of remaining thrombosis free 90 days after first use was 90.1% (95% CI = 82.9, 94.4) for arteriovenous fistula patients, but only 71.6% (95% CI = 63.5, 78.2) for polytetrafluoroethylene graft patients. In arteriovenous fistula patients with more than 30 days maturity time the risk of thrombosis was significantly lower than in those with less maturity time (RR 0.40; 95% CI = 0.14, 0.84); however, there was no significant difference for maturity time among patients with a polytetrafluoroethylene graft. Reduced thrombosis risk also was observed in patients with dialyzer blood flow rates greater than 300 mL/min (RR 0.66; 95% CI = 0.44, 0.99). Total heparin dose and erythropoietin therapy were not associated with the risk of thrombosis. No differences in risk were found for age, renal diagnosis, or type of dialyzer.

Adapting the dialysis unit to increased hematocrit levels

Recombinant human erythropoietin (epoetin) therapy had a significant impact on the practice of nephrology before its widespread use in the dialysis arena. Since then, a number of long-term studies have provided physicians with parameters for optimizing therapeutic response and patient outcomes with epoetin therapy. Fears of accelerated hypertension syndromes or increased fistula clotting are recognized as largely unfounded. There is a marked improvement in well-being, as measured by both subjective and objective parameters, as the level of anemia is reduced. Fortunately, epoetin was recognized early as essential therapy in patients on dialysis and thus was reimbursed by the Health Care Financing Administration (HCFA) and other payers, albeit through various methods of payment. Why is it, then, that hematocrit levels are still averaging approximately 30%? Perhaps the basic concern that all practitioners share is the potential for increased morbidity at "higher" hematocrit levels. Increased access clotting was not reported in the recently completed Epogen (Epoetin alfa; Amgen Inc, Thousand Oaks, CA) phase IV postmarketing study. Needle size, however, needs to be considered, because higher blood flow rates accompanied by higher hematocrit levels may lead to increased hemolysis. The venous needle size is especially important in patients who experience large weight gains. It is important to keep these issues in mind as one decides on an appropriate hematocrit level for a given patient. Hull and Eschbach reviewed postdialysis data from patients with naturally occurring high hematocrit levels and found no major changes in hematocrit level, thus alleviating the concern of significant postdialysis inspissation as a common cause for fistula clotting.