On Adult Presentations

Demographics

Sleep apnea is a very prevalent disorder in important populations. Epidemiological studies estimate the prevalence to be 2% to 4% in the general population (3,30,31), while other, more selected population studies achieved a prevalence range of 7% to 16% (2,32). Prevalence estimates (and therefore pretest probability) increase in clinical populations due to an enrichment of medical problems. Rates encountered in the primary care or hospital settings are particularly high: primary care (high risk 37.5%) (4), obese 40% to 60% (33), bariatric surgery evaluation 71% to 87% (34,35), hypertension 38% (36), stable outpatient congestive heart failure (CHF) > 50% (37,38), coronary artery disease (CAD) > 50% (39), acute stroke > 70% (40,41), and sleep clinic 67% (29).

In regards to the presentation of sleep apnea, studies show a strong relationship between age and sleep apnea (see also Chapter 16) (15,30,42,43). Duran (2) found that sleep apnea prevalence increased with age with an OR of 2.2 for each 10-year increase. The Sleep Heart Health Study noted that prevalence rose steadily with age up to 60 years at which point a plateau in prevalence occurs around 20% (15). It has also been shown that the severity of sleep apnea (42) and the effect of body mass index (BMI) seem to decrease with age (15,43) and that the magnitude of associations for sleep apnea, snoring, and breathing pauses also decreases with age (15).

Men have a higher prevalence of sleep apnea than women across all ages in epidemiological (3,31,44) and clinic-based studies (see also Chapter 14). This effect diminishes with time, however, and both sexes achieve a similar incidence by age 50 (43). A study of OSA incidence and its risk factors found the risk for sleep apnea in men increased only marginally with age, while it increased very significantly in women: the OR (confidence interval) for increased AHI per 10-year increase was 2.41 in women (1.78-3.26) and only 1.15 (0.78-1.68) in men (43). A study of Hong Kong women found a 12-fold rise in the prevalence of sleep apnea in women between the fourth and sixth decades (31). There is a large amount of literature to support the role of menopause in modulating this increased risk for sleep apnea in women around the age of 50 (44-46). In general, men and women are present with the same constellation of sleep-related symptoms and complications (47). Women with OSA may be slightly older, more obese, more likely to use sedatives, and complain of insomnia and depression (48).

It is not clear if race can be categorically used to confer risk, or if race difference is just a surrogate for a different risk profile. A study of sleep apnea risk factors in the Sleep Heart Health Study did not show a significantly higher prevalence in African-Americans (15) and another did not note any differences in respiratory disturbance index (RDI) when adjusted for known confounders (49). In contrast, a study of older community dwelling adults found that African-Americans had a 2.5 times greater odds of having an AHI > 30 (50), and the Cleveland Family Study found the prevalence of sleep apnea in young African-Americans was higher than that of Caucasians (51).

Studies in Asia estimate the prevalence of sleep apnea to be similar to that of the West (30,31). This is an intriguing finding given that obesity, the risk factor believed to modulate a large part of the risk for sleep apnea in the West, is less common in Asia. Other factors must therefore act in the expression of this disorder. Craniofacial morphology has been implicated as a modifier of risk in nonobese populations but could also interact with obesity as well (52-54).

History of Present Illness

General issues in the presentation would be the age of onset of symptoms as well as some consideration of the trajectory of illness severity. Some of these features are listed in Table 1, and includes features important in both adult and pediatric populations. The pediatric examination is also discussed in a separate section below.

Sleepiness is very common in sleep apnea patients: 38% to 51% in one epidemiological study (55) and 47% to 73% in a sleep clinic population (56). Despite this it is not associated with sleep apnea in clinical studies. This is in large part due to difficulty in differentiating sleep from fatigue. In a study of sleep apnea patients' perception of their problems, lack of energy, tiredness, and fatigue were more prevalent complaints than sleepiness (56).

Snoring is extremely common in sleep apnea patients and its absence should make OSA less likely (13). In one study only 6% of patients with OSA did not report snoring. Keep in mind however, that many patients have misperceptions about their snoring and tend to underestimate it (57). Some studies have shown that a report of "loud" habitual snoring strengthens by seven-fold the statistical association with sleep apnea and snoring (4,15,58). Witnessed apneas are relatively specific for sleep apnea, but have a low sensitivity (15).

Insomnia complaints are highly prevalent in OSA. Fifty-five percent of patients being referred for possible evaluation of OSA were noted to have complaints of insomnia, with difficulties maintaining sleep (38.8%) being more common than

TABLE 1 Features of Emphasis in the Adult and Pediatric Examination

Impact on daytime Irritability, mood swings, hyperactivity, automatic behaviors, work functioning or academic performance, behavior of concern (inappropriate napping, inattentiveness), absences from work or school Sleep/wake schedules Usual bedtime, fall asleep time, wake time, napping habits, weekday/weekend variations Customs surrounding sleep Presleep routines and related transitional objects (television, pacifier, toy, etc.)

Sleep environment Shared or private room, bed partners (including pets/toys/stuffed animals); electronics or other toys that may impede sleep routines; persistence or resolution of sleep complaints in other environments (hotels, sleepovers, etc.) Body position(s) during sleep Side sleeping and/or neck hyperextension to relieve obstruction Exposures Caffeinated beverages, tobacco products, recreational drugs

Other sleep behaviors Snoring, witnessed apneas, paradoxical breathing, mouth breathing with dry mouth and throat, morning headaches, gastroesophageal reflux, sweating (may suggest increased work of breathing), stereotypic movements/complaints suggestive of seizure or movement disorders (including parasomnias and restless legs syndrome)

difficulties initiating sleep (33.4%) or early morning awakenings (31.4%). Despite the overall high prevalence of insomnia complaints in this study population, insomnia was more common in patients without rather than with significant sleep-disordered breathing (81.5% with AHI < 10 vs. 51.7% with AHI > 10) (59). The high prevalence of insomnia complaints may be attributable to the fact that the sleep disruption associated with OSA may be perceived as insomnia, or perhaps such patients with insomnia and OSA are more symptomatic, thus more likely to seek medical attention.

Weight gain increases the probability of sleep apnea. One large population-based study found a 10% weight gain and predicted a 32% increase in AHI. This translated to a six-fold increase in the odds of developing (moderate-to-severe) sleep apnea (32). Inversely, a decrease in weight leads to an improvement in sleep apnea. Studies in bariatric surgery patients show a dramatic improvement in RDI after weight loss (35,60).

Frequent awakening from sleep to urinate is common in sleep apnea patients. One retrospective study found a prevalence of 49% in sleep apnea patients (61) and others have noted frequent nocturia is related to sleep apnea severity (61-63).

Nocturnal angina may be related to apneas in some patients with ischemic heart disease and sleep-disordered breathing. Small series in patients with ischemic heart disease and relatively severe sleep apnea suggested a link between myocardial ischemia and apneas (64,65). However, these findings conflict with a larger study that included patients with less severe sleep apnea and failed to appreciate a significant association (66).

Past Medical History

OSA will coexist with other sleep disorders. A retrospective analysis of 643 OSA patients found that 31% had another sleep disorder: 14.5% had poor sleep hygiene and 8.1% had PLMD (67). In two other studies more than 50% of sleep apnea patients complained of insomnia (59,68).

Sleep apnea is not only associated with cardiovascular disease but may directly contribute to its pathogenesis. It was present in 38% of hypertensive subjects in one study (36). A dose-response relationship is present (69) and several trials found a small but significant improvement in hypertension with sleep apnea treatment (70-72). Others suggest that the prevalence of sleep apnea in patients with CAD, postmyo-cardial infarction, CHF, and poststroke to be > 50% (37-41). Results from the Sleep Heart Health Study show increasing odds of self-reported heart failure, stroke, and CAD in subjects with a high AHI (73). Additionally, a pathogenic role is suggested by observational studies that show fewer adverse cardiovascular outcomes in treated versus untreated patients (74-76).

Several studies have found that sleep apnea is independently associated with glucose intolerance and insulin resistance (33,77). The Sleep Heart Health Study found that patients with mild and moderate/severe OSA had increased adjusted ORs for fasting glucose intolerance: 1.27 (0.98, 1.64) and 1.46 (1.09, 1.97), respectively (77). At least one treatment study has found improvement in glucose control in patients treated for sleep apnea (78).

Depression is linked to sleep apnea in a number of correlation studies. Most are small, use different instruments to measure depression, and indicate that 24% to 58% of sleep apnea patients have some measure of depression (79,80). In a larger European telephonic survey, 17.6% with a Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) breathing-related sleep disorder also had a diagnosis of a major depressive disorder (81).

Sleep apnea in the setting of pulmonary diseases is called the "overlap syndrome." Chronic obstructive pulmonary disease is the most common of these, but has a prevalence in the sleep apnea population similar to that of the general population (82). Pulmonary arterial hypertension is another disease but is much less common and the prevalence of sleep apnea in these patients is not well studied (83).

Hypothyroidism symptoms of fatigue can overlap with those of sleep apnea. Case series have reported improvement or resolution of sleep apnea in selected patients treated with thyroxine alone (84). Nonetheless, the limited evidence available suggests the prevalence of hypothyroidism in sleep apnea patients is no different than that seen in the general population (85) and routine screening in the absence of other signs of hypothyroidism is not cost-effective. Cases have also described lingual thyroids causing airways obstruction at night (86).

Glaucoma (87), end-stage renal disease (88,89), and gastroesophageal reflux disease (90,91) have been reported to occur with OSA, but the specificity of the associations are not established.

The occurrence of sleep disturbances during pregnancy is well documented, but the prevalence and incidence of specific sleep disorders is not confirmed in large-scale population studies. A spectrum of association between pregnancy and sleep disturbances ranges from an increased incidence of excessive sleepiness, insomnia, nocturnal awakenings, and parasomnias (especially restless legs syndrome) to snoring, and both obstructive and central sleep apnea (92). Although specific sleep disorders tend to emerge during different stages of pregnancy, the third trimester appears to be the most vulnerable. Of special attention are those women who gain excessive weight during pregnancy. Thus, during routine perinatal obstetrical care, the sleep history should be periodically revisited.

Social History

Sleep apnea significantly worsens after heavy alcohol ingestion (93,94). The effect of more moderate levels of alcohol ingestion on sleep apnea are not as clear and results are conflicting (95,96). Some proposed mechanisms include increased nasal resistance due to edema, and reduced hypoglossus motor nerve activity.

Data from the Wisconsin Sleep Cohort Study found current smokers to have an increased risk of having moderate sleep apnea compared to nonsmokers (OR 4.44). Heavy smokers had the higher risk (OR 40.47) (97). One sleep clinic study found current smokers to have increased adjusted odds of sleep apnea [OR 2.5, confidence interval (CI) 1.3-4.7, p = 0.0049] (98).

Family History

The Cleveland Family Study found that there is a familial aggregation to sleep apnea. Families with an index case of sleep apnea had a higher prevalence of sleep apnea than in those without (21% vs. 9%, p = 0.02) and risk increased with additional affected members (99). Ongoing genetic studies are trying to find the relative role of different anatomical risk factors in mediating this increased risk. At the present time routine assessment and testing of family members is not advocated in the absence of clinical illness.

The sleepiness and lack of concentration that accompanies sleep apnea impair work performance, driving ability (100,101) and have deleterious effects on family relationships. Commercial drivers are a special group that is receiving an increasing amount of attention, as driving risk becomes a public safety issue. Moreno et al. (102) administered the Berlin questionnaire to a large group of truck drivers and found that 26% were at high risk for sleep apnea; however, the presence of inactivity and obesity were also strongly implicated in this pretest probability estimate.

Medication History

There is an accounting of medication use for sleep apnea in Chapter 17. In general, medications to note during the history and physical fall into three categories: (i) those that are associated with OSA, (ii) those that sedate and/or decrease respiratory drive, and (iii) those that impair sleep onset or maintenance (Table 2).

Drug-induced sleepiness is the most commonly reported side effect of central nervous system active pharmacological agents; the 1990 Drug Interactions and Side Effects Index of the Physicians' Desk Reference lists drowsiness as a side effect of 584 prescription or OTC preparations (103).

Allergies

Nasal obstruction contributes to the worsening of sleep-disordered breathing, but the extent to which this might be related to allergic rhinitis is not known. One case-control study did show that sleep apnea patients had a higher rate of perennial allergic rhinitis and atopy than controls (104).

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