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Higher nocturnal and awake oxygen saturations in children with sickle cell disease receiving hydroxyurea therapy
Indra Narang1,2, Gili Kadmon3, Dennison Lai1,2
11 Division of Respiratory Medicine, and.
Insights
Hydroxyurea (HU) treatment in children with sickle cell disease improves oxygen saturation but does not affect obstructive sleep apnea frequency. This suggests HU may reduce sickle cell disease complications by enhancing oxygenation.
Area of Science:
- Pediatric Hematology
- Sleep Medicine
- Pulmonology
Background:
- Obstructive sleep apnea and nocturnal hypoxia are common in children with sickle cell disease (SCD), contributing to morbidity.
- Hydroxyurea (HU) is increasingly used for SCD, reducing vaso-occlusive crises, but its effect on sleep-related respiratory issues is unclear.
Purpose of the Study:
- To determine if HU use in children with SCD is linked to lower rates of obstructive sleep apnea (OSA).
- To assess if HU therapy is associated with improved nocturnal and awake oxygen saturation levels (SaO2) in pediatric SCD patients.
Main Methods:
- Retrospective cross-sectional study at a Canadian pediatric hospital.
- Compared polysomnogram data of SCD children on HU therapy versus those not on HU.
- Matched 37 children receiving HU with 104 children not receiving HU.
Main Results:
- No significant difference in OSA diagnosis rates between HU and no-HU groups (38% vs. 52%, P=0.14).
- Similar obstructive apnea-hypopnea index severity in both groups (median 0.9 vs. 1.9 events/h, P=0.28).
- HU group showed significantly higher median awake SaO2 (98.6% vs. 96.2%), sleep SaO2 (98.4% vs. 96.1%), and nadir sleep SaO2 (91.4% vs. 85.0%) compared to the no-HU group (all P<0.001).
Conclusions:
- HU therapy in children with SCD is associated with improved awake and nocturnal oxygen saturation.
- HU does not alter the frequency or severity of obstructive sleep apnea in this population.
- Enhanced nocturnal oxygenation may be a key mechanism for HU's benefits in reducing SCD-related morbidity.
Rationale:
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.
Objectives:
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.
Measurements And Main 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.
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