Background: Obstructive sleep apnoea syndrome (OSAS) is an independent risk factor for cardiovascular morbidity and mortality and has a detrimental effect on vascular function, in particular on arterial stiffness and endothelial function. Continuous positive airway pressure (CPAP) is the gold-standard therapy for OSAS and its effects on arterial stiffness and endothelial function have been demonstrated in non-elderly patients. Objectives: The objective of this study was to evaluate the effect of one year of CPAP treatment on arterial stiffness, through assessment of carotid–femoral pulse wave velocity (cf-PWV), and on endothelial function, through the reactive hyperaemia index (RHi), in a real-life cohort of elderly patients with moderate-to-severe OSAS and several comorbidities. Methods: In this nonrandomised prospective study, we enrolled 469 consecutive elderly patients affected by moderate-to-severe OSAS distributed in two groups: CPAP-treated (n = 225) and untreated patients (n = 244). Results: At one-year follow-up, in the treated group emerged an important improvement in poligraphics (AHI, ODI, TC90, mean SpO₂%), laboratory (HOMA index, eGFR, hs-CRP) and vascular function parameters: cf-PWV. The stepwise multivariate linear regression demonstrated a significant correlation between the delta of the polygraph parameters and the delta of PWV and RHi. Conclusions: Our study confirmed the favourable effects of CPAP therapy in a cohort of elderly patients affected by OSAS and several comorbidities on sleep respiratory parameters and vascular function; early diagnosis and treatment with CPAP might be beneficial to delay or prevent the occurrence of cardiovascular events in these groups of patients.

Introduction: Obstructive sleep apnea (OSA) is highly prevalent, affecting up to 50% of individuals over 65 years. Elderly patients often present with atypical, fewer and less severe symptoms, suggesting age-specific phenotypes. However, comprehensive clinical phenotyping that incorporates cognitive outcomes remains limited. This study aimed to characterize OSA phenotypes through cluster analysis and evaluate their association with cognitive impairment, independently of age. Materials and Methods: Between 2020 and 2024, 409 adults with moderate-to-severe OSA were enrolled and stratified into three age groups (<65, 65–74, ≥75 years). All underwent home sleep apnea testing (HSAT), comprehensive symptom assessment, Epworth Sleepiness Scale (ESS), and Montreal Cognitive Assessment (MoCA, pathological ≤ 25 pts). Hierarchical cluster analysis (Ward’s method) used AHI, T90, BMI, and ESS. Logistic regression identified independent predictors of cognitive impairment. Results: Older groups showed lower BMI, higher comorbidity burden, fewer symptoms, and greater cognitive impairment prevalence (4.5% vs. 9.7% vs. 45.9%; p < 0.001), despite comparable polysomnographic severity across age groups. Cluster analysis identified three phenotypes: Cluster 1 (classical OSA: high AHI, BMI, T90, ESS); Cluster 2 (geriatric phenotype: low AHI, BMI, T90, ESS, highest cognitive impairment rate: 27.7%); Cluster 3 (hypersymptomatic: low AHI and T90, high sleepiness and asthenia, prevalent depression). On multivariate regression, age (OR 1.155; p < 0.001), male sex (OR 2.223; p = 0.034), and Cluster 2 (OR 3.131; p < 0.001) were independent predictors of cognitive impairment. Conclusions: Three clinically distinct OSA phenotypes were identified regardless of age and severity. The geriatric phenotype was associated with three-fold increased risk of cognitive impairment, supporting routine cognitive screening and age-adapted diagnostic strategies in elderly OSA patients.