Utilization of Darbepoetin alfa in Relation to Cancer Patients’ Hemoglobin Levels.

Background: Prevailing guidelines through 2006 recommended initiating erythropoiesis stimulating agents (ESAs) for chemotherapy-induced anemia (CIA) at hemoglobin (Hb) levels <11 g/dL, maintaining near 12 g/dL, and withholding at >13 g/dL.

Objective and Purpose: To determine darbepoetin alfa (DA) administration patterns in cancer patients and selected factors related to such use.

Methods: A retrospective ESA administration-level analysis of Varian Medical Systems electronic medical records (EMRs), which includes 122,985 cancer patients across 13 states and 82 physical sites of care. The study period was 1/1/2005 – 11/30/2006. All DA administrations were recorded with the most recent Hb (day of or up to 7 days prior to administration). The proportion of DA administrations at Hb ≥ 12 and Hb ≥ 13 g/dL were the primary outcome measures. Utilization by Hb level was analyzed for all administrations, stratifying by year, gender, and anemia type. The types of anemia assessed were CIA, anemia of cancer (AOC), and myelodysplastic syndrome (MDS).

Results: During the 23 month period, there were 33,923 DA administrations associated with Hb results in 5,252 patients. The proportion of all DA administrations given at Hb≥12 was 7.7%, for Hb≥13 g/dL it was 1.1%; proportions for CIA, AOC, and MDS were 8.1 /1.2% (N = 25,638 administrations), 7.5 /1.0% (N = 7,054), and 2.3 /0.2% (N = 1,231) for Hb ≥12 and ≥13 g/dL respectively. The difference across all three indications was statistically significant (P < 0.005) for both Hb thresholds. Overall, the proportion of all DA administrations at Hb ≥12 g/dL and ≥13 g/dL declined from 8.6% to 7.1% (p<.0001) and from 1.3% to 1.0% (p<.06) respectively in 2005 vs. 2006.

Conclusions: In this population, DA administration at Hb ≥ 12 and Hb ≥ 13 occurred in approximately 7.7% and 1.1% of administrations, respectively. The results suggest that for the majority of administrations the prevailing guidelines at the time were adhered to by clinicians. Further research is required to understand dose titrations at Hb from 12 – 13 g/dL.