Risk factors for obstructive sleep apnea in adults.

OBSTRUCTIVE SLEEP APNEA (OSA) is a sleep disorder characterized by intermittent complete and partial airway collapse, resulting in frequent episodes of apnea and hypopnea. The breathing pauses cause acute adverse effects, including oxyhemoglobin desaturation, fluctuations in blood pressure and heart rate, increased sympathetic activity, cortical arousal, and sleep fragmentation. The condition has received increasing attention during the past 3 decades. Until 1981, the only effective treatment for OSA was tracheostomy. The advent of continuous positive air pressure therapy, an effective noninvasive treatment, was a turning point, and clinical interest began to increase in tandem with the accumulation of research linking OSA to cognitive, behavioral, cardiovascular, and cerebrovascular morbidities (FIGURE). Findings from large population studies in different countries during the last decade have contributed to a better understanding of the epidemiology of OSA. In most population studies, OSA status has been indicated by the frequency of apnea and hypopnea events per hour of sleep (apnea-hypopnea index) as determined by polysomnography (a continuous overnight recording of sleep, breathing, and cardiac parameters). The apnea-hypopnea index cutpoints of 5, 15, and 30 (with or without daytime sleepiness) are commonly used to indicate mild, moderate, and severe OSA, respectively. These studies have demonstrated that OSA is highly prevalent in adults (TABLE). Approximately 1 in 5 adults has at least mild OSA and 1 in 15 adults has OSA of moderate or worse severity. In the United States, 75% to 80% of OSA cases that could benefit from treatment remain undiagnosed. Associations of OSA with serious morbidity have raised concern that untreated OSA is a substantial but underappreciated public health threat. Primary care physicians are currently being encouraged to be alert to OSA symptoms of disruptive snoring, breathing pauses, and excessive daytime sleepiness in their patients. It is important that physicians also recognize that not all OSA patients are “Pickwickian” (ie, male, obese, sleepy, snoring, and middle-aged), a stereotype that emerged from clinical observations of the highly selective patient populations observed in earlier years. The goal of this article is to review recent findings from populationbased epidemiology studies on risk factors for OSA in adults.