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Few minority patients with sleep apnea have been evaluated or treated. This study ascertained adherence rate to referrals for sleep apnea evaluation by primary care physicians in a community-based sample of black patients; it also examined baseline characteristics likely to influence adherence rates.A retrospective chart audit was conducted at a hospital-based sleep clinic. Scrutiny was limited to male and female patients between the ages of 20 and 80 years. Data obtained for this analysis included baseline characteristics from a detailed sleep history and/or screening questionnaires and polysomnographic parameters.Of the 421 patients referred by their private care physicians, 38% (n=160) adhered to the recommendation for a sleep consultation, but all who showed up for their appointment underwent polysomnographic studies. Logistic regression analyses showed that obesity and daytime sleepiness were the most important factors predicting adherence, with multivariate-adjusted odds ratios of 2.69 [95% CI: 1.54-4.71, p0.001] and 6.98 [95% CI: 3.86-12.64, p0.001], respectively. Of the patients who underwent a polysomnographic sleep evaluation, 91% received a sleep apnea diagnosis and were treated.Black patients may be underutilizing available sleep services, but direct comparisons with other ethnic groups could not be made because of insufficient archival data. While the present study does not identify specific barriers to accessing services for sleep problems, it indicates that blacks who are obese and/or are experiencing daytime sleepiness are likely to adhere to recommendations of their physician. Targeted culturally congruent educational interventions to increase awareness of sleep apnea in black communities might help to increase adherence rate.

Although obstructive sleep apnea and cardiovascular disease have common risk factors, epidemiologic studies show that sleep apnea increases risks for cardiovascular disease independently of individuals' demographic characteristics (i.e., age, sex, and race) or risk markers (i.e., smoking, alcohol, obesity, diabetes, dyslipidemia, atrial fibrillation, and hypertension). Individuals with severe sleep apnea are at increased risk for coronary artery disease, congestive heart failure, and stroke. The underlying mechanisms explaining associations between obstructive sleep apnea and cardiovascular disease are not entirely delineated. Several intermediary mechanisms might be involved including sustained sympathetic activation, intrathoracic pressure changes, and oxidative stress. Other abnormalities such as disorders in coagulation factors, endothelial damage, platelet activation, and increased inflammatory mediators might also play a role in the pathogenesis of cardiovascular disease. Linkage between obstructive sleep apnea and cardiovascular disease is corroborated by evidence that treatment of sleep apnea with continuous positive airway pressure reduces systolic blood pressure, improves left ventricular systolic function, and diminishes platelet activation. Several systematic studies are necessary to explicate complex associations between sleep apnea and cardiovascular disease, which may be compounded by the involvement of diseases comprising the metabolic syndrome (i.e., central obesity, hypertension, diabetes, and dyslipidemia). Large-scale, population-based studies testing causal models linking among sleep apnea, cardiovascular morbidity, and metabolic syndrome are needed. Citation: Jean-Louis G; Zizi F; Clark LT; Brown CD; McFarlane SI. Obstructive sleep apnea and cardiovascular disease: role of the metabolic syndrome and its components. J Clin Sleep Med 2008;4(3):261–272.