Adherence to hydroxyurea therapy in children with sickle cell anemia

J Pediatr. 2010 Mar;156(3):415-9. doi: 10.1016/j.jpeds.2009.09.044. Epub 2009 Nov 1.


Objectives: To assess adherence to hydroxyurea therapy in children with sickle cell anemia (SCA), evaluate the association between adherence and hematologic profile, and identify barriers and facilitators of adherence.

Study design: Children with SCA (n=75) receiving hydroxyurea were recruited for a single-institution cross-sectional study. The primary outcome was association between treatment adherence and percent fetal hemoglobin (HbF).

Results: Good adherence was estimated at 82% with visual analog scale, 84% with Morisky score, 85% with medical provider report, 77% with clinic visits, and 49% on the basis of pharmacy refills. Increase in HbF was moderately associated with good adherence as measured with the parent/proxy Morisky score (r=-0.39; 95% CI, -0.58-0.17; P < .01) and prescription refills (r=0.39; 95% CI, 0.16-0.57; P < .01). The number of pharmacy refills and the Morisky score explained 23% of the variation in HbF response.

Conclusions: Adherence was > or =75% with 4 of 5 measures. Pharmacy refills and the Modified Morisky Scale may be used to identify children at high risk for poor response because of non-adherence and children with good adherence with poor response because of individual pharmacodynamics. Future research should prospectively compare adherence measures and evaluate methods to improve treatment adherence.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Anemia, Sickle Cell / blood
  • Anemia, Sickle Cell / drug therapy*
  • Antisickling Agents / therapeutic use*
  • Attitude
  • Child
  • Child, Preschool
  • Female
  • Fetal Hemoglobin / analysis
  • Hemoglobins / analysis
  • Humans
  • Hydroxyurea / therapeutic use*
  • Leukocyte Count
  • Male
  • Medication Adherence*
  • Pain Measurement
  • Parents / psychology


  • Antisickling Agents
  • Hemoglobins
  • Fetal Hemoglobin
  • Hydroxyurea