The Efficacy of Intravenous versus Subcutaneous Recombinant Erythropoietin in Obese African-African Patients in a Southeast U.S. Dialysis Cohort

Aims: To correct renal anemia, subcutaneous (SC) route of recombinant human erythropoietin (rhuEPO) administration has been associated with increased efficacy and decreased dose requirements, when compared with intravenous (IV) route. The effect of obesity as a potential modifier during rhuEPO administration has not been well explored.
Study Design: Single-center, Longitudinal Cohort Study.
Place and Duration of Study: University of Mississippi Medical Center Outpatient Dialysis Unit, between February and November of 2009.
Methodology: We performed IV to SC rhuEPO conversion for 86 in-center dialysis patients and, following a six-month equilibration period, we monitored outcomes over a period of three months. We obtained baseline demographic parameters, calculated Body Mass Index (BMI) and monitored iron saturation, ferritin, hemoglobin (Hgb) along with rhuEPO requirements. Patients were divided into 3 categories based on BMI [<25 (n=27), 25-35 (n=38), >35 (n= 21) kg/m2]. Results are reported either as percents, means with SD or median with 25-75% interquartile range, as appropriate.
Results: The cohort was all African-American, 48.8% male, aged 54.7 (13.3) years and BMI calculated at 29.9 (7.4) kg/m2. Baseline iron saturation was 24 (10.6)%, ferritin measured 641 (277) ng/mL. Hgb remained unchanged during the observation period: 11.1 (1.3) vs. 11.2 (1.3) gm/dL. Initial rhuEPO weekly dose for the entire cohort was 19,729 (17,448) Units/week (U/week); final dose 17,482 (14,860) U/week, with close correlation between initial and final doses (r: 0.653, P<0.0001). Weekly rhuEPO dose remained virtually unchanged in BMI categories 1 and 2 [13,927 (10,938) vs. 13,297 (10,247) U/week; 20,684 (15,788) vs. 20,997 (17.917)] (P=NS for both) but decreased in the category 3: 25,459 (24,403) vs. 16,444 (12,749) (P=0.081). However, BMI had no independent effect in linear regression modeling with multiple covariates (age, BMI, iron saturation, ferritin) included.
Conclusion: Obesity may affect relative efficacy of rhuEPO conversion; additional studies may be needed.