Factors associated with successful epoetin alfa therapy in premature infants.

OBJECTIVE

To determine the impact of two different recombinant human erythropoietin (epoetin alfa) dosing strategies on the number of red blood cell (RBC) transfusions, and explore relationships between specific patient and drug regimen variables with epoetin alfa therapy outcomes.

DESIGN

Retrospective cohort study.

SETTING

Level III university neonatal intensive care unit.

METHODS

Infants who received epoetin alfa therapy three times weekly for more than one week were categorized into two epoetin alfa dosing strategy groups: group A (300-749 units/kg/wk) and group B (750-1200 units/kg/wk). The following patient variables were collected and their relationship to therapy outcomes (corrected reticulocyte count [%], hematocrit [%], and number of RBC transfusions after therapy was started) were evaluated using independent Student's t-test, correlation analysis, and stepwise linear regression: birth weight (kg), gestational age (weeks), postnatal age at therapy onset (days), duration of mechanical ventilation (days), number of RBC transfusions before epoetin alfa therapy, phlebotomy loss (mL/kg), epoetin alfa dosage (units/kg/dose), iron dosage (mg/kg/d), duration of therapy (days), and postconceptional age at therapy discontinuation (weeks).

RESULTS

The charts of 44 patients were reviewed. No significant impact on outcome was attributed to overall dosing strategy (group A vs. group B). Linear regression identified postnatal age at therapy onset as a significant contributor to mean hematocrit (R2 = 2 0.116; p = 0.023) and postconceptional age at therapy discontinuation as a significant contributor to number of transfusions during and after epoetin alfa use (R2 = 0.118; p = 0.022). A significant positive correlation was found between weekly mean epoetin alfa dosage and mean reticulocyte count (r = 0.326; p = 0.046), mean iron dosage and mean reticulocyte count (r = 0.439; p = 0.006), and ventilator days and total number of transfusions (r = 0.606; p < 0.001). A significant negative correlation was found between number of transfusions and reticulocyte count (r = -0.367; p = 0.023).

CONCLUSIONS

Epoetin alfa dosing strategy, as defined in our study, did not significantly affect the number of transfusions. However, postnatal age at therapy initiation, postconceptional age at therapy discontinuation, mean epoetin alfa dosage, and iron dosage correlate with specific outcomes of epoetin alfa therapy in premature infants.