title: Higher nocturnal and awake oxygen saturations in children with sickle cell disease receiving hydroxyurea therapy.
abstract: BACKGROUND
  Obstructive sleep apnea and intermittent nocturnal oxygen desaturations are highly prevalent in children with sickle cell disease and have been reported to contribute to associated morbidity, including vasoocclusive disease. Hydroxyurea (HU) is increasingly used to treat children with sickle cell disease and has been shown to decrease the number and severity of vasoocclusive crises. Although there has been an increase in the use of HU, the impact of HU on the prevalence of obstructive sleep apnea and nocturnal hypoxia are not well documented.
  
  
  OBJECTIVE
  To evaluate whether the use of HU is associated with a decreased frequency of obstructive sleep apnea and higher nocturnal and awake oxygen saturations (SaO2) in children with sickle cell disease.
  
  
  METHODS
  This was a retrospective, cross-sectional review of children with sickle cell disease referred to the sleep laboratory at the Hospital for Sick Children, Toronto, Canada. Polysomnogram data in children with sickle cell disease receiving HU therapy were compared with those not prescribed HU.
  
  
  RESULTS
  Children with sickle cell disease receiving HU therapy (HU group, n = 37) were matched with children not receiving HU (no-HU group, n = 104). Obstructive sleep apnea was diagnosed in 14 of 37 (38%) and 54 of 104 (52%) in the HU group and no-HU groups, respectively (P = 0.14). The median obstructive apnea-hypopnea index was 0.9 and 1.9 events/h in the HU group and the no-HU group, respectively (P = 0.28). The HU group compared with the no-HU group had a significantly higher median awake SaO2 (98.6 and 96.2%, respectively; P < 0.0001), a significantly higher median sleep SaO2 (98.4 and 96.1%, respectively; P < 0.001), and a significantly higher nadir SaO2 while asleep (91.4 and 85.0%, respectively; P = 0.0002).
  
  
  CONCLUSIONS
  In children with sickle cell disease, the use of HU was associated with an increase in awake and nocturnal SaO2, despite there being no difference in the frequency of obstructive sleep apnea and the severity of the obstructive apnea-hypopnea index. Improving nocturnal SaO2 may be an important mechanism of action of HU therapy. The use of HU to improve nocturnal saturations across the severity spectrum of sickle cell disease may be beneficial in decreasing morbidities related to sickle cell disease.
authors.affiliation: 1 Division of Respiratory Medicine, and.|2 University of Toronto, Toronto, Ontario, Canada; and.
authors.forename: Indra
authors.initials: I
authors.lastname: Narang
authors.affiliation: 3 Schneider Children's Medical Center of Israel, Tel Aviv, Israel.
authors.forename: Gili
authors.initials: G
authors.lastname: Kadmon
authors.affiliation: 1 Division of Respiratory Medicine, and.|2 University of Toronto, Toronto, Ontario, Canada; and.
authors.forename: Dennison
authors.initials: D
authors.lastname: Lai
authors.affiliation: 1 Division of Respiratory Medicine, and.
authors.forename: Simranpal
authors.initials: S
authors.lastname: Dhanju
authors.affiliation: 4 Division of Hematology, Hospital for Sick Children, Toronto, Ontario, Canada.|2 University of Toronto, Toronto, Ontario, Canada; and.
authors.forename: Melanie
authors.initials: M
authors.lastname: Kirby-Allen
authors.affiliation: 4 Division of Hematology, Hospital for Sick Children, Toronto, Ontario, Canada.|2 University of Toronto, Toronto, Ontario, Canada; and.
authors.forename: Isaac
authors.initials: I
authors.lastname: Odame
authors.affiliation: 1 Division of Respiratory Medicine, and.|2 University of Toronto, Toronto, Ontario, Canada; and.
authors.forename: Reshma
authors.initials: R
authors.lastname: Amin
authors.affiliation: 1 Division of Respiratory Medicine, and.
authors.forename: Zihang
authors.initials: Z
authors.lastname: Lu
authors.affiliation: 1 Division of Respiratory Medicine, and.|2 University of Toronto, Toronto, Ontario, Canada; and.
authors.forename: Suhail
authors.initials: S
authors.lastname: Al-Saleh
mesh_terms: D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000150:complications* / Q000188:drug therapy*; D000986:Antisickling Agents / Q000627:therapeutic use*; D002170:Canada; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006918:Hydroxyurea / Q000627:therapeutic use*; D016015:Logistic Models; D008297:Male; D010100:Oxygen / Q000097:blood*; D017286:Polysomnography; D012189:Retrospective Studies; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*; D014851:Wakefulness
chemical_list: D000986:Antisickling Agents; D010100:Oxygen; D006918:Hydroxyurea
keywords: hydroxyurea; nocturnal oxygen saturations; obstructive sleep apnea