Potential OSA Subtypes (A-D) based on common themes in the cluster analysis studies focused on demographic characteristics, anthropometrics, comorbidities, and symptoms. aLevel is based on relative difference for that variable/feature within each study. Studies and clusters corresponding to potential OSA subtypes (X [Cluster #], where X is first initial of the study cited): Subtype A: B [1 or 5], F [1], G [3], Ke [3], M [3], Y [3]; Subtype B: B [3], G [5], Ke [2], Ki [2], M [2], V [5], Y [2]; Subtype C: G [1], F [2]; Ke [1], Ki [1], M [1], P [1], Y [1]; and Subtype D: B [4], G [4], Ke [4], V [6]. Study cited: B = Bailly et al,32 2016; G = Gagnadoux et al,34 2016; F = Ferreira-Santos and Pereira Rodrigues,33 2018; Ke = Keenan et al,30 2018; Ki = Kim et al,31 2018; M = Mazzotti et al,24 2019; Y = Ye et al,20 2014. AHI = apnea-hypopnea index; CBTi = cognitive behavioral therapy for insomnia; CVD = cardiovascular disease (coronary heart disease, heart failure, and stroke); ESS = Epworth Sleepiness Scale; Nstu = number of studies that identified analogous clusters, with 0 to 10 range selected for demonstration; PSG = polysomnography; QOL = quality of life (measured by using the Short Form-36 Health Survey); T90% = percent of total sleep (or recording) time spent with oxygen saturation below 90%.