OSA-COPD overlap syndrome is a state in which a person has both obstructive sleep apnea and chronic obstructive pulmonary disease. It is probably not a new illness. But the recognition of it as a common entity has been recent. It has important implications for both patients that have it and doctors that treat it.
The Prevalence of OSA-COPD Overlap Syndrome
Many patients with chronic obstructive pulmonary disease (COPD) have obstructive sleep apnea (OSA) and vice versa. Based on different studies conducted, the prevalence of this condition varies widely. Some studies suggest that between 9% and 56% of people with OSA also have COPD, and that COPD is present in 5% to 85% of patients with OSA.
The true prevalence of OSA-COPD overlap syndrome is unknown but based on the frequency of COPD in the general population (around 10%) and that of disordered breathing during sleep (about 5% to 10%), the estimated frequency of OSA-COPD overlap syndrome in people 40 years or older is between 0.5% and 1%. Some studies estimate the prevalence to be 4%. Others have reported an even higher frequency. The actual prevalence requires larger not-yet-performed studies though.
Consequences of OSA-COPD Overlap Syndrome
OSA-COPD overlap syndrome impacts patients primarily with respect to their quality of life and death rate if it is not properly treated. It affects how doctors evaluate and treat the COPD component of the syndrome.
Quality of Life and Mortality
The quality of life tends to be worse for patients with OSA-COPD overlap syndrome than with either condition alone. This is often borne out in more pronounced mutual symptoms. They include shortness of breath, fatigue, sleep disturbance and daytime sleepiness. Correlating signs include more severe and persistent nighttime hypoxia as well as worse hypercapnia while sleeping and during the day.
In addition to greater morbidity, studies have shown an increased mortality rate for OSA-COPD overlap syndrome compared to either condition alone. This is particularly important since COPD is the third leading cause of death in the United States and one of the leading causes worldwide. The death rate from OSA-COPD overlap syndrome is less though when it is properly treated.
Evaluation and Treatment Considerations
Because of the impact that proper treatment has on morbidity and mortality associated with OSA-COPD overlap syndrome, the suspicion or proof of it affects how doctors evaluate and treat COPD.
Diagnosing OSA-COPD overlap syndrome
It is more common for OSA-COPD overlap syndrome to escape detection due to the failure to identify OSA in a patient with known COPD than vice versa. Thus, if a diagnosis of COPD already exists polysomnography can establish or rule out the diagnosis of the overlap syndrome. Therefore, if a doctor has a high index of suspicion for OSA in a patient with known COPD the scheduling of a sleep study is in order.
There are a number of clues that a patient might have OSA along with COPD. Some are symptoms and signs that the patient reports to a doctor. They include the following:
- fatigue (particularly which is worsening)
- worsening shortness of breath
- excessive daytime sleepiness
- snoring while sleeping witnessed by an observer
- apnea and/or hypopnea while sleeping observed by another
- sleep arousals observed by another
Signs of OSA that a doctor might notice include obesity; enlarge tonsils; frequent yawning in the examination room; or dozing off in the waiting room or examination room.
OSA-COPD overlap syndrome treatment implications
Many patients with COPD require the use of oxygen to prevent or lessen hypoxemia. Oxygen treatment lowers the risk of death and improves the quality of life and sleep in many patients with severe COPD. When OSA is also present though, the use of supplemental oxygen might prolong the duration of episodes of apnea and might worsen hypercapnia, either of which can result in death.
Several studies have shown that positive airway pressure in the form of CPAP or BiPAP has a positive effect on the health and lifespan of OSA patients. Likewise, there is evidence from clinical studies that CPAP lowers the death rate of patients with OSA-COPD overlap syndrome. The benefit applies to both COPD patients that do and that don’t require oxygen. Therefore, CPAP is the first line of treatment for patients with overlap syndrome. Thus, the use of oxygen alone by patients with COPD without the supervision of a doctor is ill- advised and is risky.