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.

Asthma is associated with higher rates of acute chest syndrome (ACS) and vaso-occlusive pain episodes among children with sickle cell anaemia (SCA). Aeroallergen sensitization is a risk factor for asthma. We hypothesized that aeroallergen sensitization is associated with an increased incidence of hospitalizations for ACS and pain. Participants in a multicentre, longitudinal cohort study, aged 4-18 years with SCA, underwent skin prick testing to ten aeroallergens. ACS and pain episodes were collected from birth until the end of the follow-up period. The number of positive skin tests were tested for associations with prospective rates of ACS and pain. Multivariable models demonstrated additive effects of having positive skin tests on future rates of ACS (incidence rate ratio (IRR) for each positive test 1·23, 95% confidence interval [CI] 1·11-1·36, P < 0·001). Aeroallergen sensitization was not associated with future pain (IRR 1·14, 95%CI 0·97-1·33, P = 0·11). Our study demonstrated that children with SCA and aeroallergen sensitization are at increased risk for future ACS. Future research is needed to determine whether identification of specific sensitizations and allergen avoidance and treatment reduce the risk of ACS for children with SCA.