Impact of Obstructive Sleep Apnea Complicated With Type 2 Diabetes on Long‐term Cardiovascular Risks and All-cause Mortality in Elderly Patients

Abstract

BackgroundThe prognostic significance of obstructive sleep apnea (OSA) in elderly patients with type 2 diabetes is unclear. The aim of this study was to determine the risk of cardiovascular disease (CVD) and mortality in elderly patients with OSA complicated with type 2 diabetes compared to patients with OSA without type 2 diabetes.MethodsFrom January 2015 to October 2017, 1113 eligible elderly patients with OSA were enrolled in this consecutive multicentre prospective cohort study. An apnoea-hypopnoea index of ≥5 events per hour recorded by polysomnography was defined as the diagnostic criterion for OSA. We collected baseline demographics, clinical characteristics, sleep parameters and follow-up outcomes. The primary aim of this study was to determine the risk of incident major adverse cardiovascular events (MACE). Secondary outcomes were all-cause mortality, components of MACE and a composite of all events. Kaplan-Meier survival analysis and Cox proportional hazards models were used to evaluate whether type 2 diabetes was associated with incident events.ResultsA total of 266 (23.9%) patients had OSA complicated with type 2 diabetes. MACE occurred in 97 patients during the median 42-month follow-up. Kaplan-Meier survival curves indicated a significant relationship between OSA and MACE (log-rank P=0.003). Multivariable Cox regression analysis showed that type 2 diabetes increased the risk of MACE (HR=1.68, 95% CI:1.10-2.58, P=0.018), hospitalisation for unstable angina (HR=1.87, 95% CI:1.03-3.39, P=0.038) and a composite of all events in elderly patients with OSA (HR=1.72, 95% CI:1.12-2.64, P=0.012). However, there were no significant differences in the incidence of cardiovascular death, all-cause mortality, MI and hospitalisation for heart failure between patients with and without diabetes (P>0.05). The subgroup analysis demonstrated that females (AHR=2.50, 95% CI:1.15-5.43, P=0.021), ≥ 70 years (AHR=1.99, 95% CI:1.08-3.65, P=0.027), overweight and obese (AHR=1.75, 95% CI:1.10-2.80, P=0.019) with mild OSA (AHR=2.30, 95% CI: 1.01-5.26, P=0.49) were at a higher risk for MACE by diabetes.ConclusionOSA and type 2 diabetes are interrelated and synergistic with MACE, hospitalisation for unstable angina and a composite of all events development. Overweight and obese females, ≥ 70 years with mild OSA combined with type 2 diabetes presented a significantly high MACE risk.