Evidence-based medicine and sleep apnea

There is an increasing body of evidence that obstructive sleep apnea (OSA) affects systemic blood pressure and quality of life. The evidence linking OSA with other types of cardiovascular morbidity and mortality is not as strong. We review the current literature on the health impact, diagnosis, and treatment of OSA and provide a framework for evaluating levels of evidence in each of these areas, with the focus on high quality studies. Clinical prediction rules and unattended portable monitoring devices, such as digital oximeters, are inexpensive and have clinically useful likelihood ratios, sensitivity, and specificity, so they can be considered clinically useful in the evaluation of individuals suspected of having OSA. This approach has the potential to change the probability of disease in some patients to a level at which polysomnography is unnecessary. Recent randomized, placebo-controlled trials have indicated that treating OSA with continuous positive airway pressure improves quality of life, driving simulator performance, blood pressure, and sleepiness. The evidence in support of mandibular advancement is less strong, and surgical measures should be viewed as an option only after continuous positive airway pressure and mandibular advancement have been considered, given the paucity of evidence to support surgery. The quality of research done on the prognosis, diagnosis, and treatment of OSA has improved substantially in recent years. However, there remains a need for additional studies that evaluate ambulatory monitors and for larger randomized controlled trials of therapy with longer patient follow-up to verify the range of benefits that OSA patients can expect from the various treatment modalities.