Urinary biomarkers and obstructive sleep apnea in patients with Down syndrome.

STUDY OBJECTIVES The study aimed to compare urinary biomarkers in patients with Down syndrome (DS) with and without obstructive sleep apnea (OSA) to those of age- and sex-matched neurotypically developing healthy controls (HC). We further investigated whether we could predict OSA in patients with DS using these biomarkers. METHODS Urine samples were collected from 58 patients with DS the night before or the morning after their scheduled overnight polysomnogram or both, of whom 47 could be age- and sex-matched to a sample of 43 HC. Concentrations of 12 neurotransmitters were determined by enzyme-linked immunosorbent assay. Log-transformed creatinine-corrected assay levels were normalized. Normalized z-scores were compared between patients with DS vs. HC, between patients with DS with vs. without OSA, and to derive composite models to predict OSA. RESULTS Most night-sampled urinary biomarkers were elevated among patients with DS relative to matched HC. No urinary biomarker levels differed between patients with DS with vs. without OSA. A combination of four urinary biomarkers predicted AHI > 1 with a positive predictive value of 90% and a negative predictive value of 68%. CONCLUSIONS Having DS, even in the absence of concurrent OSA, is associated with a different urinary biomarker profile when compared to that of HC. Therefore, while urinary biomarkers may be predictive of OSA in the general pediatric population, a different approach is needed in interpreting urinary biomarker assays in patients with DS. Certain biomarkers also seem promising to be predictive of OSA in patients with DS. No clinical trial was indicated in the undertaking of this work.