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Researchers examine anemia, dialysis methods, and nephrologist referral among patients with kidney disease

Four studies supported in part by the Agency for Healthcare Research and Quality recently examined health issues confronting individuals who suffer from chronic renal insufficiency (CRI) and acute renal failure (ARF). The first study (National Research Service Award fellowship F32 HS00143) reveals that CRI patients typically develop anemia long before they reach end-stage renal disease (ESRD), but management of this anemia is suboptimal even among nephrologists. A second study (HS08365) finds that early referral of CRI patients to a nephrologist reduces their risk of hemodialysis-related complications.

A third study (HS09398) shows that late referral to a nephrologist, considered common enough to be a public health problem, does not influence the type of dialysis treatment patients receive, but it may influence switching from the less costly peritoneal dialysis to more costly hemodialysis. A fourth study (HS06466) suggests that continuous hemodialysis, a new alternative to intermittent hemodialysis (IHD), does not improve survival of ICU patients with acute renal failure over IHD, but study limitations suggest the need for more research. All four studies are described here.

Kazmi, W.H., Kausz, A.T., Khan, S., and others (2001, October). "Anemia: An early complication of chronic renal insufficiency." American Journal of Kidney Diseases 38(4), pp. 803-812.

Individuals apparently develop severe anemia (hematocrit [Hct] less than 30 percent) early in the course of CRI and long before they develop ESRD. Treatment of anemia with recombinant human erythropoietin (rHuEPO) and supplemental iron can improve left ventricular hypertrophy and reduce hospitalizations for congestive heart failure among patients with CRI and ESRD. Unfortunately, management of this type of anemia is suboptimal, even among patients under the care of nephrologists. Doctors clearly need to be educated about anemia management of patients with CRI, conclude these researchers.

They retrospectively studied 605 adults with elevated serum creatinine levels indicative of CRI (greater than 1.5 mg/dL in women and 2.0 mg/dL in men) in nephrology practices in the Boston area to identify factors associated with severe anemia and examine anemia management practices in CRI patients. Anemia began early during the course of CRI and progressively worsened with deteriorating renal function. Even at serum creatinine levels less than 2 mg/dL, 45 percent of patients had an Hct less than 36 percent. By the time these patients were referred to a nephrologist, 59 percent had an Hct less than 36 percent and 15 percent had an Hct less than 30 percent. Moreover, anemia worsened during followup.

Among patients with severe anemia, only 11 percent and 27 percent were being administered rHuEPO and iron at the time of the first visit, and this figure increased to 55 percent and 44 percent during followup, respectively. Current guidelines for dialysis and predialysis patients recommend a target Hct for rHuEPO therapy between 33 percent and 36 percent. The fact that third-party payers often do not pay for rHuEPO before ESRD until the patient has an Hct less than 30 percent, and that many patients made few visits to the nephrologist, may partly explain low use of this drug.

Astor, B.C., Eustace, J.A., Powe, N.R., and others (2001, September). "Timing of nephrologist referral and arteriovenous access use: The CHOICE study." American Journal of Kidney Diseases 38(3), pp. 494-501.

Arteriovenous (AV) vascular accesses for hemodialysis provide greater blood flow rates than percutaneous dialysis catheters and are associated with much lower rates of blood clots, infection, and narrowing of blood vessels. For this reason, guidelines recommend placement of an AV vascular access (crafted natural portal or synthetic graft) before beginning chronic hemodialysis therapy to prevent the need for complication-prone dialysis catheters. Yet referral to a nephrologist within a few months of anticipated need for dialysis often allows insufficient time for adequate vascular-access preparation, demonstrating the need for much earlier referral, conclude the researchers. They examined the questionnaire responses and laboratory and medical record data collected for a nationally representative group of 356 ESRD patients.

The proportion of patients using an AV access at the beginning of hemodialysis therapy increased from 10 percent for those referred to a nephrologist less than 1 month, to 32 percent for those referred 1 to 4 months, 28 percent for those referred 4 to 12 months, and 46 percent for those referred more than a year before they began hemodialysis therapy. Similarly, patients referred to a nephrologist within a month of beginning hemodialysis used a dialysis catheter for a median of 202 days compared with 64, 67, and 19 days (probably just until AV access matured) for patients referred 1 to 4, 4 to 12, and more than 12 months before beginning hemodialysis therapy, respectively.

Patients referred at least 4 months before beginning hemodialysis were more likely than patients referred later to use an AV fistula, rather than a synthetic graft, as their first AV access (45 vs. 31 percent). These associations remained after adjustment for age, sex, race, education, insurance coverage, coexisting illness, underlying renal diagnosis, and other factors. Unfortunately, regardless of the time of referral, fewer than 33 percent of patients used an AV access at the initiation of hemodialysis, and more than 25 percent had not used an AV access 6 months after beginning hemodialysis. Factors other than timing of referral to a nephrologist may have a significant impact on the lack of timely AV-access creation in these patients.

Winkelmayer, W.C., Glynn, R.J., Levin, R., and others (2001). "Late referral and modality choice in end-stage renal disease." Kidney International 60, pp. 1547-1554.

This study found that choice of initial renal replacement therapy by patients with end-stage renal disease (ESRD) was not associated with timing of nephrologist referral, after accounting for patient clinical and sociodemographic characteristics. However, those referred to a nephrologist 3 months or less prior to beginning peritoneal dialysis (PD), which can be done at home and is less costly than hemodialysis (HD), were more likely than those referred earlier to switch from PD to HD within 6 months. Late referral of CRI patients to a nephrologist can impair educated choices and lead to inadequate preparation for PD. In addition to the cost savings associated with PD compared with HD, early referral may minimize or delay the costs when switching from PD to HD is necessary.

The researchers analyzed New Jersey Medicare/Medicaid claims data on all patients who started hemodialysis between 1991 and 1996 and were diagnosed with renal disease more than a year prior to hemodialysis. Of this group, 35 percent had their first nephrologist consultation 3 months or less prior to initiation of dialysis. After controlling for patient demographic characteristics, socioeconomic status, and underlying renal disease, age and race influenced the choice of initial treatment methods, but timing of the referral did not.

However, patients starting on peritoneal dialysis (PD) who were referred late were nearly 50 percent more likely to switch to hemodialysis (HD) than were patients who saw a nephrologist earlier. This effect was very pronounced in the first month of treatment but was not present in the following months. This suggests that some patients may have acclimated to PD as their treatment modality. On the other hand, perhaps because they did not have appropriate vascular access for HD, some patients may have started hemodialysis on PD to bridge the period until their fistula or graft was ready to use. In patients originally on HD, diabetic nephropathy and black race influenced the likelihood of switching to PD, but the timing of referral did not.

Mehta, R.L., McDonald, B., Gabbai, F.B., and others (2001). "A randomized clinical trial of continuous versus intermittent dialysis for acute renal failure." Kidney International 60, pp. 1154-1163.

Despite advances in intensive care unit (ICU) and dialysis technology over the past four decades, death rates due to acute renal failure (ARF) remain distressingly high, with in-hospital mortality rates ranging from 50 to 80 percent. The worldwide standard of care for ARF requiring dialysis in the ICU is intermittent hemodialysis (IHD). Continuous hemodiafiltration techniques, which have recently emerged as alternative therapies for these patients, do not improve their survival over IHD, according to this study.

However, this study did not control for other factors that might influence ARF outcomes such as nutrition support, hemodynamic support, timing of dialysis initiation, and dose of dialysis. Also, despite randomization, patients in the continuous therapy group were sicker, and more of them had liver failure than those in the IHD group. This could explain their higher mortality rates. More studies of larger groups of patients are needed to better compare the benefits of these two types of hemodialysis, conclude the researchers.

Their multicenter trial randomized 166 ICU patients with ARF to either IHD or continuous hemodiafiltration. Overall ICU and in-hospital mortalities were 50.6 and 56.6 percent, respectively. Continuous therapy was associated with more ICU deaths (59.5 vs. 41.5 percent) and in-hospital deaths (65.5 vs. 47.6 percent) than intermittent dialysis. Median ICU length of stay from the time of nephrology consultation was 16.5 days, and complete recovery of renal function was observed in 34.9 percent of patients, with no significant group differences.

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