Abstract / Summary
Background: Positional obstructive sleep apnea (POSA), defined as obstructive events that occur predominantly in the supine position, is considered a phenotype of obstructive sleep apnea (OSA) that requires a special diagnostic and therapeutic approach.Children with Down syndrome (DS) are at increased risk of having OSA in general and POSA in particular.However, the clinical and sleep determinants of POSA in DS are not well characterized.Objective: To determine the prevalence of POSA in children with DS with OSA, compare the clinical and polysomnographic characteristics between POSA and non-POSA phenotypes, and identify predictors of POSA.Methods: The study is a retrospective evaluation of the entire cohort of children with genetically confirmed DS who completed a diagnostic polysomnography study at the only pediatric sleep lab in Qatar between September 2019 and May 2026.Patients' demographic, clinical, and polysomnographic data were collected from the medical records.Only patients with OSA were included in the analysis.OSA was defined as an obstructive apnea-hypopnea index (AHI) ≥ 1.5 events/hour.OSA was considered positional (POSA) if the ratio of supine to non-supine AHI was ≥2, with at least 20 minutes of sleep recorded in both the supine and non-supine positions.Non-positional (non-POSA) if the ratio was < 2. Comparisons between POSA and non-POSA groups were made using Student's t-test for continuous variables and a chi-square test for categorical variables.Multivariable logistic regression was performed in the study population to identify potential independent predictors of POSA.Results: A total of 151 children with DS were identified.Only 132 (87%) of the children had OSA.POSA was identified in 61 (46.2%) children and non-POSA in 71 (53.8%) children.There was no significant difference between the two groups in age, gender, weight, height, BMI, or history of snoring or witnessed apnea.There was also no significant difference between the two groups in sleep efficiency, sleep architecture, AHI, OAHI, or OSA severity.Regression analysis showed no significant clinical or PSG predictors of POSA in the study population.Conclusions: POSA is prevalent in children with DS.However, there are no significant clinical or polysomnographic differences between POSA and non-POSA, suggesting that POSA is not a unique OSA phenotype.Further prospective and interventional studies are needed to confirm the clinical impact of POSA in DS and its treatment.