Does sleep-disordered breathing contribute to the clinical severity of sickle cell anemia?

Purpose: This research was undertaken to determine whether obstructive sleep apnea (OSA) and/or nocturnal hemoglobin desaturations contribute to the clinical severity of sickle cell anemia (SS), Patients and Methods: Eleven patients with severe SS (group S), defined by two or more hospitalizations in the previous year for painful crises, were compared to eight patients with mild SS (group M) who had not been hospitalized for painful crises in the past year. An additional cohort of nine patients with SS who had been referred to the Sleep Disorders Center because of a clinical suspicion of OSA were studied (group R). All patients underwent full overnight polysomnography and performed standard pulmonary function tests. Results: There were no significant differences in the respiratory disturbance index (RDI; apneas plus hypopneas per hour of sleep) or hemoglobin desaturation between the mild and severe groups, and neither RDI nor hemoglobin saturation predicted the number of painful crises. Despite a suggestive clinical presentation, only 44% of the patients in group R had OSA confirmed polysomnographically. Conclusions: In this preliminary study, unsuspected nocturnal cardiopulmonary disease and hemoglobin desaturation did not explain the variability in the severity of SS disease. However, OSA can occur in patients with SS, and when clinically suspected, the diagnosis should be confirmed with overnight polysomnography so that appropriate treatment can be instituted.