The prevalence of overlap syndrome in obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) in Medicare beneficiaries increased 4-fold from 2004 to 2013, according to a study published in Annals of the American Thoracic Society.

Chronic obstructive pulmonary disease

(COPD) is a type of obstructive lung disease characterized by long-term breathing problems and reduced airflow. The main symptoms include shortness of breath and cough with sputum production COPD is a progressive disease, meaning it typically worsens over time eventually, everyday activities, such as walking or getting dressed, become difficult. Chronic bronchitis and emphysema are older terms used for different types of COPD.

The term "chronic bronchitis" is still used to define a productive cough that is present for at least three months each year for two years. Tobacco smoking is the most common cause of COPD, with factors such as air pollution and genetics playing a smaller role.

In the developing world, one of the familiar sources of air pollution is poorly vented heating and cooking fires. Long-term exposure to these irritants causes an inflammatory response in the lungs, resulting in narrowing of the small airways and breakdown of lung tissue. The diagnosis is based on poor airflow as measured by lung function tests.  In contrast to asthma, the airflow reduction does not improve much with the use of a bronchodilator.

Using Medicare enrollment and claims data from 2004 to 2013, researchers included patients with COPD (N=141,568), 11% of whom had coexisting OSA (n=17,516). Exclusion criteria included age ≤65 years, residence in a nursing facility, or enrollment in an HMO plan.

OSA diagnosis was defined as 1 healthcare encounter with an OSA diagnosis with polysomnography (PSG), repeated for each year (2004-2013), and continuous positive airway pressure (CPAP) machine usage. Demographic data including age, gender, race, socioeconomic status, and region were analyzed; COPD complexity and number of comorbidities were also included.

Overlap syndrome diagnoses increased from 4.04% to 17.80% based on visits for OSA, 1.49% to 7.97% based on having a PSG, and 0.99% to 5.01%, based on having a PSG and prescription for a CPAP device.

Patients with overlap syndrome were more likely to be younger, male, have higher numbers of comorbidities, and have more complex COPD than patients with COPD alone. Limitations as a result of the study design include usage of diagnostic coding rather than clinical laboratory testing to assess the prevalence of overlap syndrome.  The inclusion of fee-for-service Medicare beneficiaries may compromise generalizability to non-Medicare populations.

The researchers stated that when they examined the prevalence of OSA in a 5% fee-for-service non-COPD Medicare population during the same 10-year period, they “found that the overall prevalence of OSA in patients with COPD is much higher than that seen in the general population.”