Sleep disordered breathing does not predict acute severe pain episodes in children with sickle cell anemia

Conflicting evidence has suggested that low mean nocturnal hemoglobin oxygen saturation (SpO₂ ) predicts future hospital days for acute severe pain in children with sickle cell anemia (SCA). In an unselected multicenter prospective cohort study, we tested the hypothesis that either low mean nocturnal SpO₂ or high obstructive apnea-hypopnea index (OAHI; the number of obstructive apneas and hypopneas with ≥ 3% desaturation or arousal per hour of sleep) or high oxygen desaturation index (ODI; number of ≥ 3% desaturation from baseline saturation per hour of sleep) is associated with increased incidence rates of pain. A total of 140 children with SCA with a median age of 10.8 years (interquartile range 7.2) were followed for a median of 4.9 years (interquartile range 1.8). Overnight polysomnography evaluations at baseline health exam were measured and adjudicated centrally. Multivariable models created in two steps were included. First, all plausible covariates were included in a screening model. Subsequently, covariates meeting level of statistical significance of P < .20 were included in the final model. Contrary to our hypothesis, higher (but not lower) mean nocturnal SpO₂ was associated with higher rates of pain episodes (Incidence rate ratio (IRR) 1.10, 95% CI [1.03-1.18], P = .004). Higher log OAHI did not pass screening criteria. Higher log ODI was not significantly associated with higher rates of pain episodes (IRR 0.93, 95% CI [0.82-1.06], P = .28). Neither low nocturnal SpO2, higher OAHI, nor higher ODI were associated with clinically relevant increased incidence rates of acute severe pain episodes.