Obesity Epidemic Fuels Obstructive Sleep Apnea Diagnoses

ORLANDO — Obstructive sleep apnea (OSA) that puts patients and those around them at risk can be minimized by early recognition and treatment or referral to a specialist, according to a primary care pulmonary medicine practitioner.

As many as 10% of adults in the U.S. have OSA, which goes unrecognized or undiagnosed in 75-80% of cases, said Ashley York, DNP, of Samford University in Birmingham, Alabama, during the American Association of Nurse Practitioners annual meeting.

The prevalence of OSA differs by patient age and sex. Men have a higher prevalence than women until age 50, after which the prevalence is similar between the sexes. York said older women have a fivefold greater prevalence of OSA than younger women, whereas the prevalence doubles in older versus younger men.

OSA prevalence has increased in parallel with the obesity epidemic. Every 10% weight gain increases the risk of OSA by sixfold, and patients with OSA have higher levels of the hunger hormone leptin, which makes weight loss especially difficult.

“We have a lot of studies showing that any compliance with CPAP (continuous positive airway pressure) will improve leptin,” said York. “The higher levels of that hunger hormone make it really hard for patients with OSA to lose weight and really easy for them to gain weight.”

Any weight loss reduces the severity of OSA. In some cases, patients are able to reduce reliance on CPAP or stop it altogether and switch to an oral appliance during sleep, she added.

OSA’s association with multiple conditions and risk factors likely contributes to the large percentage of cases that go unrecognized, as well as the estimated at-risk population: 25% of all adults in the U.S. Common contributing risk factors include excess weight, hypertension, family history of sleep disorders, sleeping on the back, a history of sedation, large neck circumference, chronic nasal congestion, and airway abnormalities, in addition to male sex and older age.

Rarely an Isolated Condition

OSA rarely occurs in isolation from other health issues. Most patients have one or more of the following comorbidities: type 2 diabetes, tobacco use (current or historical), ischemic heart disease, chronic obstructive pulmonary disease, hypercholesterolemia, congestive heart failure, atrial fibrillation or flutter, and gastroesophageal reflux disorder, as well as hypertension, obesity, and tonsillar/adenoidal hypertrophy.

Apnea confers a variety of clinical consequences that include sleep fragmentation, hypoxia, hypercapnia, excess daytime sleepiness and neurocognitive effects (especially alertness and mental focus), and complications associated with the cardiovascular, endocrine, and gastrointestinal systems. The consequences add up to increased morbidity and mortality, said York.

Sleep apnea also poses risks to others, she continued, as people with OSA have as much as a five times greater risk of automobile accidents. The risk of other types of accidents is also increased and exacerbated by increased body mass index, a higher apnea-hypopnea index (AHI), and severity of hypoxemia.

A simple, four-question assessment can point clinicians toward an OSA diagnosis:

1. Has your snoring/breathing at night bothered others or yourself?
2. Do you feel excessively tired during the day or fall asleep easily?
3. Have you been told you stop breathing or choke while sleeping?
4. Do you have hypertension or type 2 diabetes?

Positive answers to two or more of the questions should be followed up with one or more additional assessments, said York: the Berlin Questionnaire, Epworth Sleepiness Scale, BMI, and/or neck circumference measurement. Neck circumference ≥17 inches for men and ≥15 inches for women is consistent with a diagnosis of OSA.

Homing in on Diagnosis

The presence of common signs and symptoms can further guide the differential diagnosis toward OSA: excessive daytime sleepiness and/or fatigue, unrefreshing sleep, loud or disruptive snoring, morning headaches, depression, nocturia, difficulty concentrating, irritability, and erectile dysfunction.

Positive findings on a physical exam can provide more support for an OSA diagnosis. Oropharyngeal crowding is common in patients with OSA. Crowding can occur as a result of tonsillar enlargement, an enlarged/elongated or swollen uvula, or macroglossia. Craniofacial and nasal passage abnormalities are common findings of a physical exam. Some patients will have signs of right-heart failure or strain, such as edema or jugular vein distention.

The Mallampati score, originally developed to assess patients for difficulty of intubation, has also proven useful in evaluating patients with suspected OSA. Though somewhat subjective in nature, the 4-point scale reflects increasing degrees of crowding, closing, or lack of visibility at the back of the throat. A score of 1 or 2 is usually a negative indicator, whereas most patients with a 3 or 4 have OSA, said York.

If the accumulation of evidence from history, signs, and symptoms point toward OSA, the next step is to recommend a sleep test. The recommendation can be to a sleep clinic or lab or for a home sleep apnea test. A sleep clinic will offer a polysomnographic evaluation, which provides more data and clinical insight but also is more expensive. York said a home test is a good option when the pretest probability for OSA is high or for patients who do not have insurance or the insurance does not cover sleep testing. A home sleep apnea test is less expensive but also provides fewer data.

Two scores are key indicators for an OSA test result, and the results have potential implications for insurance coverage, said York. The AHI represents the combined number of apneic and hypopneic events per hour of sleep. An AHI <5 is normal, whereas a score of 5-15 represents mild apnea and a score >30 indicates severe sleep apnea.

The respiratory disturbance index (RDI) reflects the combined number of apneic, hypopneic, and respiratory effort-related arousal events per hour of sleep. AHI and RDI can differ, particularly when used to evaluate young, thin patients, York said.

Insurers differ with respect to coverage on the basis of AHI or RDI. Medicare, for example, will not cover OSA treatment if a patient has an AHI score <5. However, some insurers will cover treatment for a patient with an RDI >5 in association with OSA symptoms, even with an AHI <5.

Treatment recommendations will vary depending on the severity of OSA, insurance coverage, and a variety of patient-specific factors, including personal preference. Options include different types of positive airway pressure, oral appliances, surgery, upper airway stimulation, weight management, positional therapy, and cognitive behavioral therapy. The options should be discussed with each patient and lead to a shared decision, which might involve more than one intervention.