What Is Asthma-COPD Overlap Syndrome?

Asthma-COPD overlap syndrome is highly prevalent, but an understanding of its causes and proper treatment is lacking. Here's what you should know.

Purposefully and very publicly, the World Asthma Foundation (WAF) has declared “war” on a syndrome that it says is “terribly underappreciated” but common and very dangerous.

If you have the syndrome you suffer attacks of breathlessness from an overlap of asthma and chronic obstructive pulmonary disease (COPD).

The prevalence of these acute attacks from what is called asthma-COPD overlap syndrome (ACOS) is nearly 2.5 times higher than for people with COPD alone. Accordingly, the risk of these dangerous episodes is twice as high than is it for people with COPD alone, the WAF says.

There has been a scramble within the medical research community to better understand and define the syndrome, along with a continued debate on how to treat it.

“Discussions about those individuals who have features of both asthma and COPD is a hot topic at medical meetings,” says Donald A Mahler, MD, a practicing pulmonologist and emeritus professor at Dartmouth University. “It is important to understand this overlap, or combination, because different medications are used to treat asthma and to treat COPD.”

In a recent study, researchers examined more than 800 patients with COPD and through blood tests found that 15 percent of them also had asthma, or asthma-COPD overlap syndrome. Most with the condition were male, and more than 60 percent were taking an inhaled corticosteroid.

If you have a respiratory disease, this study is important. Mahler says COPD is treated with inhaled bronchodialtors. But asthma is treated with corticosteroids that, when used daily, make asthma symptoms less likely to occur.

Mahler believes that inhaled corticosteroids should be used to treat COPD “mainly for those who have experienced frequent episodes of worsening of COPD due to a chest infection (exacerbation).” But, he adds that use of the corticosteroids to treat COPD increases risk of pneumonia.

One study reviewed what pulmonologists think about ACOS because there is no “universally accepted (diagnostic) criteria” to define it. The authors acknowledged “most treatments (now used) for asthma and COPD have not been adequately tested” for people who might have the syndrome.

This clinical conundrum, as it has been described, includes agreeing on whether ACOS even exists as a distinct condition. Half of the pulmonologists involved focus on treating asthma, half on COPD. About 85 percent “recognized the existence” of ACOS and said a mean of about 13 percent of their patients might have it.

A previous history of asthma, smoking, and difficulty breathing that can’t be fully reversed are the main characteristics, the study said. The authors concurred with Mahler that “first-line” treatment should be long-acting corticosteroids.

Meanwhile, another study attempted to find the mechanism the triggers what becomes ACOS. The researchers reported that both smokers and nonsmokers with chronic asthma have features of the syndrome.

The study found that many patients with asthma are at risk of developing COPD from a “cascade” of inflammation and protein breakdown that causes lung tissue damage. While that phenomenon is common in smokers, why it also happens in nonsmokers remains a mystery, the authors added.

This means that, for you, a diagnosis of ACOS as opposed to separate diagnoses of asthma or COPD remains challenging for doctors. Even half of Americans with COPD haven’t been diagnosed.

There is a meeting of the minds on one aspect of ACOS. “There is broad agreement that patients with features of both asthma and COPD experience frequent exacerbations, have poor quality of life, a more rapid decline in lung function and high mortality,” according to the Global Initiative for Asthma.

Help for you may come from the Global Initiative for Chronic Obstructive Lung Disease (GOLD), which has developed guidelines for diagnosis and treatment based on an exhaustive review of the current evidence on ACOS.

The guidelines describe ACOS as “characterized by persistent airflow limitation with several features usually associated with asthma and several features usually associated with COPD. ACOS is therefore identified by the features that it shares with both asthma and COPD.”

So, because much of ACOS is simply about awareness at this point, you need to talk to your doctor about the condition if you have asthma or COPD because either one may develop into the overlap syndrome.

Patients with any of the three chronic diseases will cough a lot, have labored breathing, wheeze, and experience chest tightness. Your doctor can sometimes differentiate the diseases by knowing the age of onset and the triggers. Asthma tends to strike younger patients and those with a family history of the disease, for example. It’s triggered by cold weather, smoke fumes, exercise, among other substances. COPD tends to be triggered by respiratory infections.

Also, you may never have smoked and still have asthma, but COPD and ACOS patients have a history of smoking or exposure to “biomass fuels,” meaning burning wood or other substances used to cook or heat.

There are other differentiators included in the GOLD guidelines. It may help you to read them and have them with you if you see your doctor about a chronic respiratory problem. It gives you both a reference point, and that’s what the WAF “war” is really all about.