Obstructive Sleep Apnea
Published Dec 3, 2019 · S. Patel
Annals of Internal Medicine
55
Citations
1
Influential Citations
Abstract
Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper airway closure during sleep that result in recurrent oxyhemoglobin desaturation and sleep fragmentation. OSA syndrome is defined by the combination of OSA and resulting symptoms (typically daytime sleepiness). In the general adult population, OSA syndrome occurs in 14% of men and 5% of women (1). The prevalence of OSA is increasing in conjunction with increasing rates of obesity (1), with 5-year incidence of 7%11% in middle-aged adults (2). Despite this, only about 1 in 50 patients with symptoms suggestive of OSA syndrome is evaluated and treated for the disease (3). The most common symptoms associated with OSA include snoring that is bothersome to others, nocturnal awakening, nocturia, unrefreshing sleep, and daytime sleepiness resulting in reduced quality of life. It also impairs the sleep quality of bedpart-ners. If left untreated, OSA can have long-term consequences, such as increased risk for motor vehicle and occupational accidents (4). In addition, the physiologic stresses from repetitive upper airway obstruction can lead to increased blood pressure (5). OSA is associated with increased risk for atrial fibrillation, heart failure, and stroke as well as type 2 diabetes and Alzheimer disease. However, whether treatment can prevent or reverse these conditions is unclear. Screening and Prevention Who should be screened for OSA? Because most patients with OSA symptoms do not report them to their primary care provider (6), there is reason to believe that screening could be beneficial. The U.S. Preventive Services Task Force has highlighted the lack of high-quality research to justify routine screening for OSA (7). Nevertheless, the American Academy of Sleep Medicine (AASM) recommends asking all adults whether they are dissatisfied with their sleep or have daytime sleepiness as part of a routine health maintenance evaluation (8). This can be achieved by including sleep as part of a review of systems. Those with positive responses should be screened for OSA by using further clinical history or screening instruments. Patients with risk factors should also be screened (see the Box: Risk Factors for Obstructive Sleep Apnea). Because obesity is a major risk factor for OSA, all obese patients should be screened. Excess weight is responsible for 41% of all cases and 58% of moderate to severe cases (9), and risk for OSA increases as obesity increases. Of note, patients of East Asian heritage are at risk for OSA at lower levels of obesity than other racial groups because of differences in facial bone structure. Risk Factors for Obstructive Sleep Apnea Obesity, especially with body mass index >35 kg/m2 Family history of obstructive sleep apnea Retrognathia Treatment-resistant hypertension Congestive heart failure Atrial fibrillation Stroke Type 2 diabetes Polycystic ovary syndrome Acromegaly Down syndrome The AASM also recommends screening patients with a family history of OSA and those who have retrognathia. Patients who have high-risk driving occupations, such as commercial truck drivers and public transit operators, should be screened for OSA because of the potential public health effect, and any patient with a history of a recent motor vehicle crash or near miss attributable to sleepiness should be screened (10). Screening should also be done in patient populations with diseases that commonly co-occur with OSA. For example, in those with treatment-resistant hypertension, atrial fibrillation, heart failure, stroke, and type 2 diabetes, the prevalence of OSA is high, ranging from 35%85%. What screening tools can be used? Several screening questionnaires have been developed to identify high-risk patients (7, 11), but none is as accurate as formal sleep testing. The Berlin Questionnaire and the STOP-BANG (see the Box) screening test are 2 widely used, well-validated instruments. The Berlin Questionnaire (Supplement) was developed for a primary care population and consists of 10 questions focused on the severity of snoring, witnessed apnea, the significance of daytime sleepiness, and the presence of obesity and hypertension. When the questionnaire was evaluated in a primary care setting, more than 1 in 3 respondents was found to be at high risk for OSA and sensitivity was 86% for predicting OSA (12). Supplement. Berlin Questionnaire The STOP-BANG screening test was developed to assess patients in the preoperative setting. It is an 8-item tool with 1 point for each item. A score of 3 or higher among preoperative patients had a sensitivity of 84% for predicting any OSA, and a score of 5 or higher was more predictive of clinically relevant, moderate to severe OSA (13). STOP-BANG Screening Test* STOP S Do you snore loudly (louder than talking or loud enough to be heard through closed doors)? T Do you often feel tired, fatigued, or sleepy during the day? O Has anyone observed you stop breathing during sleep? P Do you have or are you being treated for high blood pressure? BANG B Body mass index >35 kg/m2? A Age >50 years? N Neck circumference >40 cm? G Gender male? *In a perioperative setting, answering yes to 3 questions indicates high risk for obstructive sleep apnea. Answering yes to 5 questions indicates high risk for moderate to severe obstructive sleep apnea. Can OSA be prevented? Weight gain over time is associated with OSA incidence: A 10% increase in weight predicts a 6-fold increase in the likelihood of developing clinically significant OSA (14). As such, avoiding weight gain reduces OSA risk. Furthermore, weight loss of 10% among patients followed over 10 years predicted a 26% decrease in OSA severity. Among patients with mild OSA, nearly 9 in 10 who lost an estimated 15% of body weight through diet and lifestyle modification achieved remission (15). Clinical Bottom Line: Screening and Prevention Although there is no strong evidence to justify routine screening, it is reasonable to consider asking about sleep problems as part of a review of systems, particularly in high-risk populations. Patients with sleep symptoms should be screened with further clinical history or validated questionnaires for OSA. Prevention should focus on achieving and maintaining an ideal body weight. Diagnosis What symptoms should prompt consideration of OSA? Symptoms of OSA are shown in the Box. Snoring has the highest sensitivity for OSA but is nonspecific (16). To distinguish simple snoring from that suggestive of OSA, patients should be asked for details about the snoring. Patients with OSA are more likely than simple snorers to report loud, nightly snoring that is bothersome to others (12). Symptoms of Obstructive Sleep Apnea Loud, frequent, bothersome snoring Witnessed episodes of apnea Choking/gasping during sleep Excessive daytime sleepiness Drowsy driving (recent motor vehicle accident or near miss associated with sleepiness) Unrefreshing sleep Frequent nocturnal awakening Sleep-maintenance insomnia (prolonged wake after sleep onset) Nocturia Morning headaches Decreased concentration (brain fog) Depressed mood Irritability Decreased libido Excessive daytime sleepiness is also a nonspecific finding but is critical to elicit in determining therapy options and following the response to therapy. The Epworth Sleepiness Scale (Figure 1) is an 8-item scale that quantifies the propensity for dozing off during everyday activities (17). Although correlation with objective measurements of sleepiness is inconsistent and correlation with OSA severity is poor, it can help standardize the evaluation of a patient's subjective perception. It can also be used to follow response to therapy. The Epworth Sleepiness Scale has been adopted by many insurance plans as a required part of the sleep history before payment for a sleep study is authorized. A history of drowsiness or falling asleep while driving should be explicitly explored. Patients should also be questioned about consumption of caffeine or other stimulants because it may indicate attempts to self-treat sleepiness. Figure 1. Epworth Sleepiness Scale. Although imperfect, this scale can be a useful guide to quantifying the subjective concept of sleepiness. Scores >10 are consistent with excessive daytime sleepiness and should prompt further clinical evaluation. Although relatively insensitive, choking or gasping during sleep is highly specific for moderate to severe OSA, as is the presence of morning headaches (16). Obtaining a history from a bedpartner or cohabitant can be particularly helpful because many of these symptoms may not be apparent to the patient. Manifestations of untreated OSA may also include depressive symptoms, decreased libido, and frequent nocturnal awakening. Patients with OSA can describe being in a brain fog or having difficulty concentrating as opposed to sleepiness. Of note, OSA can sometimes present in an atypical fashion, with insomnia and fatigue as the predominant symptoms, particularly in women. Sleep-maintenance insomnia (difficulty with falling back to sleep after nocturnal awakening) is more likely related to OSA than sleep-onset insomnia (18). Despite population-based studies that found a 2:1 malefemale ratio of prevalence, utilization data indicate that the malefemale ratio for referrals is 9:1, suggesting that clinicians do not adequately consider OSA in women (19). In the absence of symptoms, what other diseases should prompt evaluation? No high-level evidence supports routine testing for OSA in asymptomatic patients. However, diagnostic testing in asymptomatic, morbidly obese patients scheduled for bariatric surgery may be reasonable given the high prevalence in this population, the association of OSA with adverse perioperative outcomes (20), and low-level evidence that peri-operative treatment improves outcomes (21). Evaluation and treatment of OSA may also benefit asymptomatic patients with hypertension that is refractory to 5 or more medications. Prevalence of OSA is extremely hig