The healthcare costs of uncontrolled asthma in the United States are estimated to total $300 billion over the next twenty years, according to new research published online in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

After adding in the cost of lost productivity, researchers calculate that the total costs of uncontrolled asthma during that time period will approach a trillion dollars ($963.5 billion in 2018 dollars). The authors also calculate that American teenagers and adults will lose more than 15 million quality-adjusted life years. A quality-adjusted life year is one year of perfect health, so it captures both the quantity and quality of years lived.

The researchers write that several factors contribute to the high cost of uncontrolled asthma and the staggering loss of quality of life. Barriers to implementing evidence-based practices and the need for more effective medicines for people with severe or exacerbation-prone asthma contribute to uncontrolled asthma.

“As a clinician, I have seen hospitalization rates for acute asthma decrease, but this study shows the huge societal burden from what I call the ‘iceberg effect’ of uncontrolled asthma in the general population, which is not readily recognized,” said co-author J. Mark FitzGerald, MD, a professor of medicine at the University of British Columbia in Canada.

In conducting their study, the researchers analyzed data for the entire US population age 15 and older, using information from the Census Bureau, Bureau of Labor Statistics, the Centers for Disease Control and Prevention (CDC), the US National Health and Wellness Survey and Global Burden of Disease studies.

The direct costs of uncontrolled asthma estimated in the study are for healthcare services over and beyond what patients with controlled asthma use. The indirect cost of uncontrolled asthma was based on the study’s estimate that the average person with uncontrolled asthma will lose about six-and-a-half more weeks of work each year compared with someone whose asthma is controlled.

According to the CDC, about 26 million Americans have asthma. During the next 20-years, the number of Americans with asthma is expected to grow by 10 percent. Sixty-two percent of those with asthma will be women, and 52% of all those with asthma will have uncontrolled asthma.

The study also estimated the direct and indirect costs of uncontrolled asthma over 20 years for each state. The state with the highest average total cost of uncontrolled asthma was Connecticut ($6,132 per resident); the lowest was Arkansas ($2,209 per resident). State-specific estimates can be found using a web app the researchers developed:

A limitation of the study was that it did not include children under the age of 15. Including the burden of uncontrolled asthma in children should further increase the estimates of costs and loss of quality of life, according to the authors.

Still, the researchers write that their study highlights the sizeable potential for cost-saving and improvement in quality of life associated with better asthma control.

Senior author Mohsen Sadatsafavi, MD, PhD, a health economist and an assistant professor of health outcomes at the University of British Columbia, said that the study results indicate that research into improving adherence to existing medications should be put on an equal footing with investments in novel asthma therapies.

“While developing new therapies is important, especially for those whose asthma in not well controlled with current medications, we should also recognize the gaps in care that can be addressed with existing treatments,” he said. “Healthcare management organizations, patient groups, governments, and society at large will benefit from investing in better asthma management, which has the potential to improve the quality of life of millions of patients and reduce costs.”