Clinical correlates of steady‐state oxyhaemoglobin desaturation in children who have sickle cell disease

Abstract

Individuals with sickle cell disease (SCD) may have oxyhaemoglobin desaturation during the steady‐state, the causes of which are incompletely known. We studied a cohort of 585 children who have sickle cell anaemia (SS), sickle β⁰‐thalassaemia (Sβ⁰), sickle‐haemoglobin C disease (SC), or sickle β⁺‐thalassaemia (Sβ⁺) to determine the relationships between steady‐state oxyhaemoglobin saturation (SpO₂) and SCD genotype, age, gender, steady‐state haemoglobin (Hb) and reticulocyte count, and rate of acute chest syndrome (ACS). The SS/Sβ⁰ group (n = 390) had lower mean SpO₂ than the SC/Sβ⁺ group (n = 195) (96·3% vs. 98·7%, P < 0·001). Among SS/Sβ⁰ subjects, a decrease in steady‐state SpO₂ correlated with a decrease in Hb, an increase in reticulocytes, older age and male gender. These correlations were not found in the SC/Sβ⁺ group. Prior ACS did not correlate with steady‐state SpO₂. A multivariate model explained 45% of the variability in SpO₂, but only 5% of the variation in SpO₂ was explained by Hb. We conclude that steady‐state desaturation is common in individuals with SCD, but it appears to be unrelated to prior episodes of ACS and largely unexplained by chronic anaemia.