Predictors of Mortality in Hypertensive Older Patients With Obstructive Sleep Apnea: The Role of Intermittent Hypoxia

Objective: Obstructive sleep apnea (OSA) is highly prevalent in older adults and is associated with hypertension and adverse cardiovascular, metabolic, and neurocognitive outcomes. However, the prognostic significance of OSA severity in the elderly remains controversial. The Apnea–Hypopnea Index (AHI) prognostic value in older patients may be attenuated due to aging-related physiological changes and a high prevalence of cardiovascular comorbidities. Increasing evidence suggests that parameters reflecting intermittent hypoxia may better represent the biological impact of OSA in this population. Design and method: We conducted a retrospective cohort study including patients aged >65 years with a diagnosis of OSA established by nocturnal cardiorespiratory monitoring between January 2015 and July 2018 at the IRCCS INRCA Respiratory Medicine Outpatients Centre. AHI, oxygen desaturation index (ODI), mean nocturnal oxygen saturation (SpO2), SpO2-nadir, mean of lowest SpO2, and the percentage of recording time spent with SpO2<90% (T90%) were evaluated. Clinical characteristics, cardiovascular and metabolic comorbidities, laboratory data, and pharmacological therapies were collected. The primary endpoint was all-cause mortality, assessed after a median follow-up of 92,5 months [IQR 76,7–111,0]. Results: n=194 (mean age 74,1±6,4 years; M 68.6%). During follow-up, 62 deaths (32.0%) occurred. Mean BMI was 31,4±5,8 kg/m2. Mean AHI= 28,9±17,0 events/hour and ODI 38,8±20,3 events/hour. Mean Systolic Blood Pressure 140,4±14,6 mmHg and Diastolic Blood Pressure 77,1±10,0 mmHg. SCORE2/SCORE2-OP was 20,5±8,5%. Hypertension was present in 88,6% of participants, hypertensive heart disease in 70,1%, dyslipidemia in 87,9%. OSA severity defined by AHI was not associated with mortality in univariate analyses (p=0,651) or Kaplan–Meier curves (p=0,971) (Fig.1). No oximetric parameter independently predicted mortality, although T90% >15% showed a near-significant association (HR 1,64; p=0,052) (Fig.2). Age (HR 1,11; p<0.001), coronary artery disease (HR 2,05; p=0,015), and atrial fibrillation (HR 2,35; p=0,005) were independent predictors of mortality.Conclusions: In older patients with OSA, long-term mortality is mainly driven by cardiovascular comorbidities rather than conventional sleep apnea severity indices. Hypertension likely plays a key role as a prevalent comorbidity. Intermittent hypoxia parameters may contribute to risk stratification, warranting evaluation in larger studies.