Perihospitalization patterns of hemoglobin levels and erythropoiesis-stimulating agent doses in US hemodialysis patients, 1998-2009

Anemia management in hemodialysis patients is of primary importance for clinicians and dialysis providers. Through a retrospective claims analysis, we studied prevalent US hemodialysis patients 1998-2009, and examined patterns of hemoglobin levels and erythropoiesis-stimulating agent (ESA, epoetin [EPO], and darbepoetin [DPO]) doses surrounding hospitalization events. Medicare outpatient claims were used to determine monthly ESA doses and associated hemoglobin levels. ESA dose trajectories were defined with repeated measures models incorporating an autoregressive covariance matrix that compared subsequent measurements with the index month of hospitalization, with variance component covariance matrices chosen for pair-wise comparisons. Regarding prehospitalization hemoglobin levels, a biphasic pattern occurred in both the EPO (1998-2009, n=161,242) and DPO (2004-2009, n=4391) populations; levels rose from 1998 to 2004, fell thereafter in the EPO population, and fell after 2006 or 2007 in the DPO population. In the EPO population, the proportions of patients with hemoglobin less than 10g/dL were 30.1% in 1998, 14.5% in 2004, and 28.3% in 2009; corresponding values for the DPO population were 21.0% in 2004 and 31.6% in 2009. While some degree of year-to-year variability occurred, EPO dose trends were less pronounced, with an apparent peak in 2004 followed by a modest decline; trends were similar for DPO. Trends in EPO dose trajectories did not completely parallel those for hemoglobin level; while EPO doses increased yearly up to 2004, doses stabilized, but did not materially decrease after 2004. No definite annual trends for DPO dose trajectories were apparent.