Nocturnal and awake oxygen saturations are higher in children whose sickle cell disease (SCD) is treated with hydroxyurea, according to the results of a study by Dr. Indra Narang of the Hospital for Sick Children in Toronto and her colleagues.

“Improving SaO2 [oxygen saturation] may be an important mechanism of action of hydroxyurea therapy. As such, improving SaO2 across the severity spectrum of SCD may be beneficial in decreasing SCD morbidities with an overall improvement in long-term health,” the researchers wrote.

Sickle cell disease is characterized by development of rigid and sickled cells when deoxygenated, which may result in vasoocclusive injury to organs. Hydroxyurea enhances the production of fetal hemoglobin and can lead to less acute chest syndrome and vasoocclusive crises. Furthermore, children with sickle cell disease have a high prevalence of obstructive sleep apnea, which is associated with nocturnal desaturations and may be related to morbidity in SCD.

To evaluate the role of hydroxyurea in nocturnal oxygen saturations in pediatric patients, the researchers conducted a cross-sectional review of pediatric SCD patients referred for polysomnograms at the Hospital for Sick Children in Toronto from May 2007 to May 2014. Polysomnography data were analyzed on 37 children with SCD on hydroxyurea and matched with 104 children with SCD not treated with hydroxyurea. SAO2 was assessed using the Masimo oximeter (Ann Am Thorac Soc. 2015 July;12[7]1044-9).

Obstructive sleep apnea was found in 38% (n = 14) of subjects treated with hydroxyurea versus 52% (n = 54) in the nonhydroxyurea group. In the hydroxyurea group, the median obstructive apnea-hypopnea index was 0.9 events/hr vs. 1.9 events/hr in the nonhydroxyurea group, Dr. Narang and her associates reported.

Compared with the nonhydroxyurea SCD group, the hydroxyurea SCD group had significantly higher median awake (98.6% vs. 96.2%; P less than .0001) and sleep oxygen saturations (98.4% vs. 96.1%; P less than .0001). Likewise, treatment with hydroxyurea was associated with a significantly higher sleep oxygen saturation nadir when compared with the nonhydroxyurea group (91.4% vs. 85%; P = .0002), the investigators said.

Finally, treatment with hydroxyurea was associated with higher hemoglobin levels than no hydroxyurea treatment (P less than .0001) and the hemoglobin levels significantly correlated with sleep, awake, and lowest nocturnal oxygen saturation (P less than .0001).

The authors said that they had no conflicts to disclose.