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Hemoglobin variability: impact on anemia management practices.

Article Excerpt
An expanding body of evidence on the benefits of sustaining higher hemoglobin (Hb) levels led the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI[TM]) Anemia Work Croup to recommend a target Hb range of 11 to 12 g/dL (NKF-K/DOQI, 2001). While the potential benefits of maintaining higher Hb levels are clear, trend analyses indicate that a significant percentage of patients continue to have Hb levels below the minimum recommended by NKFK/DOQI[TM] (United States Renal Data System, 2002). One of the primary challenges encountered by many clinicians is how to stabilize patients within the narrow 1-g/dL target Hb range recommended by NKF-K/DOQI[TM]. The guidelines acknowledge this difficulty, stating that the wide variation in interpatient (different patients) and intrapatient (same patient) response to Epoetin alfa therapy results in a bell-shaped distribution of Hb, with some patients temporarily exceeding the range and others dipping below or failing to achieve the minimum value (NKF-K/DOQI, 2001). This article examines the phenomenon of Hb variability, including clinical interventions that may help improve Hb stability and overall outcomes.

Vaxiability in Hb Levels: What Do the Data Show?

Analyses have consistently demonstrated that most dialysis patients are not routinely maintained in the target Hb range of 11 to 12 g/dL. Data from the 2001 Centers for Medicare & Medicaid Services (CMS) End-Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) analysis (formerly the Core Indicators Project), for example, show that more than 60% of dialysis patients have Hb levels outside the NKF-K/DOQI[TM] range (Table 1). These statistics have remained consistent for several years and have been reconfirmed by analyses conducted by the USRDS (Centers for Medicare & Medicaid Services, 2001; USRDS, 2002).

At face value, these data appear to indicate that a substantial percentage of patients never reach the target Hb range of 11 to 12 g/dL. And, in fact, some clinicians hale suggested that dialysis facilities may not be actively intervening to ensure appropriate improvement in Hb levels for all patients. To evaluate this hypothesis, a recent study was undertaken to quantify: (a) what the extent of inter and intrapatient Hb variability in the dialysis population is, (b) what the likelihood is that patients will achieve and maintain Hb levels within the target range of 11 to 12 g/dL, and (c) whether active anemia management interventions are being undertaken for patients whose Hb levels are above or below the NKF-K/DOQI[TM] target range. This analysis tracked all patients who were in the Fresenius Medical Care North America database and were undergoing dialysis from January 1 through December 31, 2000 (n = 65,009). Hb values with in the first 3 months (quarter 1) were averaged for each patient, who were then categorized into one of three Hb cohorts using these baseline values: (a) Hb 12 g/dL (n = 19,525). Over the succeeding 3 quarters, patients were tracked to determine whether Hb levels remained stable or moved into one of the other Hb categories over the course of the year (Lacson, Ofsthun, & Lazarus, 2003).

Results showed that the percentage of patients within each of these three Hb...