Obstructive sleep apnea (OSA) is a disorder characterized by repeated episodes of partial or total upper airway obstruction that result in arousals from sleep, and changes in oxygen levels during sleep. OSA is one of the most common conditions I see as a sleep medicine specialist. This is not surprising, considering that OSA is estimated to affect about 20% of the general population, and is even more prevalent in patients who are obese, or who have heart or metabolic conditions like diabetes.
When untreated, OSA can negatively impact cardiac and metabolic health, quality of life, and result in excessive daytime sleepiness, insomnia, problems with thinking, and depression or anxiety. OSA impacts people of all ages, backgrounds, shapes, and sizes, and while both patients and doctors have become increasingly aware about OSA and its effects over recent years, about 80% of patients with OSA still go undiagnosed.
How is OSA diagnosed?
The severity of OSA is based on the number of respiratory sleep disruptions per hour of sleep during a sleep study, also called the apnea-hypopnea index (AHI). Basically, the higher the AHI, the more severe the sleep apnea. Most population studies suggest that about 60% of people with OSA fall into the mild category. In general, many studies demonstrate a linear relationship between the AHI and adverse health outcomes, lending strong support for treatment of moderate and severe OSA, but with less clear-cut support for clinical and/or cost-effective benefits for treating mild OSA.
Scores for OSA don’t always correlate with symptoms
Regardless of the criteria for categorizing OSA as mild, moderate, or severe, the severity of disease does not always correlate with the extent of symptoms. In other words, some people with very mild disease (based on their AHI) can be extremely symptomatic, with excessive sleepiness or severe insomnia, while others with severe disease have subjectively good sleep quality and do not have significant daytime impairment.
Sleep disorders also tend to overlap, and patients with OSA may suffer from comorbid insomnia, circadian (internal body clock) disorders, sleep movement disorders (like restless legs syndrome) and/or conditions of hypersomnia (such as narcolepsy). To truly improve a patient’s sleep and daytime functioning, a detailed sleep related history is needed, and sleep issues must be addressed via a comprehensive, multidimensional, and individualized approach.
Treatment approaches depend on the severity of your OSA
When sleep apnea is moderate or severe, continuous positive airway pressure (CPAP) is considered the first-line treatment, and is the recommended treatment by the American Academy of Sleep Medicine (AASM). CPAP, by eliminating snoring, breathing disturbances, and drops in oxygen saturation, can essentially normalize breathing during sleep. However, to be most beneficial, CPAP should be worn consistently throughout sleep. Unfortunately, many studies of OSA set a relatively low bar for treatment adherence (many use a four-hour-per-night threshold), and do not necessarily take into account treatment efficacy (whether sleep apnea and related daytime symptoms persist despite treatment).
What about mild sleep apnea?