Erythropoiesis-stimulating protein therapy and the decline of renal function: a retrospective analysis of patients with chronic kidney disease.

BACKGROUND/AIMS: Previous studies have hinted at possible associations between anemia and progression of renal disease. The study objective was to determine whether treatment with erythropoiesis-stimulating proteins (ESPs) can curb the rate of decline in renal function in predialysis patients with chronic kidney disease (CKD). METHODS: Observational, before/after analysis using electronic medical records from the Veterans Administration (VA). Included patients had at least two measurements of serum creatinine levels before and after ESP treatment initiation. The Cockcroft-Gault formula was used to derive estimates of glomerular filtration rate (GFR). Rate of renal function decline prior to and following initiation of therapy were compared. RESULTS: One hundred and twenty two patients with renal impairment levels of Stage 3 (moderate) or Stage 4 (severe) at ESP treatment initiation were identified. Over 80% of patients initiated therapy with either Grade 1 or Grade 2 anemia. The rate of renal function decline was calculated as the slope of the least-squares linear regression line of the inverse serum creatinine over time during the pre-treatment initiation and post-treatment initiation time periods. Overall, patients experienced a slowing in the rate of renal function decline after treatment was initiated (mean pretreatment initiation rate of -0.094 dL/mg/yr versus mean post-treatment initiation rate of -0.057 dL/mg/yr). CONCLUSION: Renal function declined at a slower rate following ESP initiation. Results are consistent with prior studies indicating delayed dialysis initiation in patients treated with ESPs. Analyses were limited by the observational study design and lack of information regarding some potential confounders. Longer-term, prospective trials are needed to determine whether ESPs slow progression of renal disease and the potential magnitude of such an effect.