Consequences of Obstructive Sleep Apnea
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CME CREDIT HARNEET K. WALIA, MD, FAASM Associate Professor of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH; Staff, Sleep Disorders Center, Neurological Institute, Cleveland Clinic Beyond heart health: Consequences of obstructive sleep apnea ■ ABSTRACT bstructive sleep apnea (OSA) is a seri- Obstructive sleep apnea (OSA) is a serious condition ous condition that impacts quality of life associated with impaired quality of life, depression, and causes drowsy driving and depression. drowsy driving and motor vehicle accidents, metabolic O Research also reveals an interrelationship disease, and cognitive decline. The mechanisms account- between OSA and metabolic disease and an associa- ing for OSA and metabolic disease include hypoxia, tion between OSA and cognitive impairment. sleep fragmentation, and systemic infl ammation. OSA The diagnostic criteria of OSA are based on the appears to advance cognitive decline, and the relationship number of apneic or hypopneic episodes per hour between the 2 conditions may be bidirectional. Treatment of sleep, called the apnea–hypopnea index (AHI) of patients with continuous positive air pressure therapy as recorded during sleep testing. Diagnosis of OSA improves many of the impaired outcomes associated with is warranted if the AHI is 15 or more per hour or if OSA. Greater awareness, screening, and treatment of the AHI is 5 or more per hour with 1 or more of the patients with OSA can reduce the negative consequences following features: sleepiness; nonrestorative sleep; associated with OSA. fatigue or insomnia; waking up with breath-holding spells, gasping, or choking; snoring or breathing ■ KEY POINTS interruptions; or a coexisting diagnosis of hyperten- sion, mood disorder, cognitive dysfunction, coronary OSA is associated with negative health consequences artery disease, stroke, congestive heart failure, atrial such as depression, drowsy driving, metabolic disease, fi brillation, or type II diabetes.1 and cognitive decline. Many patients with an AHI less than 15 may also have OSA, given the number of coexisting medical Several possible mechanisms to explain the health conditions included in the OSA diagnostic criteria. consequences of OSA have been explored. Heart conditions such as coronary artery disease, atrial fi brillation, and congestive heart failure encom- Treatment of patients with OSA may improve outcomes passed in the OSA diagnostic criteria have increased for many of the health consequences associated with awareness of the link between OSA and heart health. OSA. Less well-known, and the subject of this review, are the negative consequences of OSA, particularly poor Screening for OSA is important to identify and treat quality of life, drowsy driving, depression, metabolic patients to reduce the associated health risks. disease, and cognitive impairment. ■ QUALITY OF LIFE Reduced quality of life is the most fundamental patient-reported outcome of OSA. OSA is associ- Dr. Walia is principal investigator of a ResMed funded grant. ated with excessive daytime sleepiness, inattention, This article is based on Dr. Walia’s “Beyond Heart Health: Consequences of and fatigue, which increase the risk of accidents and Obstructive Sleep Apnea” webcast released March 29, 2019, part of the medical disability. These quality-of-life impairments “Obstructive Sleep Apnea: A Cleveland Clinic State-of-the-Art Review” on- are often the main reason patients seek medical care line series (available at www.clevelandclinicmeded.com/online/sleep-apnea/ 2 default.asp). The article was drafted by Cleveland Clinic Journal of Medicine for sleep disorders. Improved quality of life is a cen- staff and was then reviewed, revised, and approved by Dr. Walia. tral goal of OSA treatment and is the best indica- doi:10.3949/ccjm.86.s1.04 tor of the effectiveness of treatment.3 Sleep health CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 86 • SUPPLEMENT 1 SEPTEMBER 2019 19 Downloaded from www.ccjm.org on October 2, 2021. For personal use only. All other uses require permission. OSA CONSEQUENCES dents in drivers with untreated OSA TABLE 1 is 6 times greater than in the general Symptoms of depression and obstructive sleep apnea (OSA) population.7 In a study of men and women in Depression Depression or OSA OSA the general population (N = 913), Sadness, anhedonia, Daytime sleepiness, fatigue, loss Snoring, witnessed individuals with moderate to severe agitation, guilt, of energy, poor concentration, apneic episodes, OSA (AHI > 15) were more likely weight loss irritability, psychomotor retardation, snorting to have multiple motor vehicle acci- weight gain dents in the course of 5 years (odds ratio = 7.3) compared with those with Data from reference 13. no sleep-disordered breathing.10 The association between OSA and motor vehicle accidents is independent of and its effect on quality of life is an area of focus of sleepiness, and drivers with OSA may not perceive Healthy People 2020 (healthypeople.gov). performance impairment. The American Academy of Sleep Medicine identi- There are 2 main reasons OSA increases the risk fi ed quality of life, along with detection of disease and and incidence of motor vehicle accidents. OSA cardiovascular consequences, as an outcome measure causes changes in attention and vigilance resulting for assessing the quality of care for adults with OSA.2 from sleep deprivation and fragmentation. OSA also The assessment of quality of life for patients with OSA affects global cognition function, which may be due is a 4-part process: use evidence-based therapy, moni- to intermittent hypoxia attributable to OSA.2 tor the therapy, assess symptoms with a validated tool Treatment for OSA is effective in reducing the such as Epworth Sleepiness Scale, and assess the inci- incidence of motor vehicle accidents. One study dence of motor vehicle accidents. Information from found the risk of motor vehicle accidents was elimi- these 4 processes can inform changes in a patient’s nated with the use of CPAP treatment in patients quality of life. with OSA.11 A recent study of nearly 2,000 patients Treatment for OSA has been shown to improve with OSA found a reduction in self-reported near- quality of life. A study of 2,027 patients with OSA accidents from 14% before PAP therapy to 5.3% after evaluated therapy adherence relative to mean Func- starting PAP therapy.12 tional Outcomes of Sleep Questionnaire and Euro- pean Quality of Life-5D scores.4 In patients with ■ DEPRESSION the most impaired quality of life, those adherent to Depression can occur as a consequence of OSA. positive airway pressure (PAP) therapy had improved Depression and OSA have several symptoms in com- quality of life as measured by these scores. mon (Table 1).13 With respect to sleepiness, a systematic review of Estimates of the prevalence of depression in continuous PAP (CPAP) in patients with OSA found patients with OSA range from 5% to 63%.13,14 One a 2.7-point reduction (mean difference; 95% confi - year after patients were diagnosed with OSA, the dence interval 3.45–1.96) in the Epworth Sleepiness incidence of depression per 1,000 person-years was Scale in patients using CPAP compared with the 14 5 18% compared with 8% in a group without OSA. control group. Treatment of OSA improves patient Women with OSA reportedly have a higher risk of quality of life and symptoms such as sleepiness. depression (adjusted hazard ratio [HR] 2.7) than men 14 ■ (HR 1.81) at 1-year follow-up. In the same study, DROWSY DRIVING with respect to age, there was no signifi cant relation- Drowsy driving by people with OSA can lead to motor ship noted between OSA and patients over age 64. vehicle accidents, which result in economic and A one-level increase in the severity of OSA (ie, from health burdens.6,7 National Center for Statistics and minimal to mild) is associated with a nearly twofold Analysis data reveal that of 6 million motor vehicle increase in the adjusted odds for depression.15 On the accidents (5-year average, 2005–2009), 1.4% involve other hand, studies have also found that patients on drowsy driving and 2.5% of fatal crashes involve antidepressants may have an increased risk of OSA.16 drowsy driving.8 Among noncommercial drivers, Several potential mechanisms have been proposed untreated OSA increases the risk of motor vehicle to explain the link between depression and OSA.13 accidents 3- to 13-fold.9 The odds ratio of traffi c acci- Poor-quality sleep, frequent arousal, and fragmentation 20 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 86 • SUPPLEMENT 1 SEPTEMBER 2019 Downloaded from www.ccjm.org on October 2, 2021. For personal use only. All other uses require permission. WALIA of sleep in OSA may lead to frontal lobe emotional are said to have syndrome Z24 and are at increased modulation changes. Intermittent hypoxia in OSA risk of cardiovascular morbidity and mortality.25 Syn- may result in neuronal injury and disruption of nor- drome Z imparts a higher risk of atherogenic burden adrenergic and dopaminergic pathways. Pro-infl amma- and prevalence of atheroma compared with patients tory substances such as interleukin 6 and interleukin 1 with either condition alone.26 In comparing patients are increased in OSA and depression and are media- with metabolic syndrome with and without OSA, tors between both conditions. Neurotransmitters those with OSA had increased atherosclerotic burden may be affected by a disrupted sleep-wake cycle. And as measured by intima-media thickness and carotid serotonin, which may be impeded in depression, could femoral pulse-wave velocity.27 Syndrome Z is also infl uence the upper-airway dilator motor neurons. linked to intracoronary stenosis related to changes Treatment of OSA improves symptoms of depres- in cardiac morphology28 and is associated with left sion as measured by the Patient Health Questionnaire ventricular hypertrophy and diastolic dysfunction.29 (PHQ-9).