Table 1. Synthesis of articles selected for systematic review on prevalence, etiology, correlating factors, screening methods, and biomarkers for obstructive sleep apnea in Down syndrome patients (age>18 years).

Author/year	Study	N° of patients	Mean age (years/months)	Time of follow up	Outcome	Conclusion
Carvalho et al., 2020 49	Case series-Questionnaires; blood county	60 (DS)	>18 years	-	Adults with DS have a very high prevalence of OSA. Hematocrit levels, STOP-Bang questionnaires (SBQ) showed a strong correlation with OSA severity. The SBQ performed well in identifying moderate to severe OSA in this population.	Considered together, these results point to the need to perform OSA screening in all adults with DS, and STOP-Bang may play a role in this screening.
Capone et al., 2013 38	Case Control-PSG; Reiss and ABC scales	37 (9C) (28 DS)	19.8 (C) 21 (SD) years	5 years	–86% of DS cases had OSA compared with 44% of controls; –Moderate-severe OSA was present in 54% of DS compared to 11% of controls; –Intermittent sleep-associated hypoxia and REM sleep deficits were also more frequent in DS. Across all subjects, prior tonsillectomy was not related to the presence or absence of OSA.	The results of the study suggest that OSA is a common comorbidity in adolescents and young people with DS and depression.

OSA: obstructive sleep apnea; DS: Down syndrome.