Impacts of severe persistent asthma vary across US
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Key takeaways:
- 23.7% of patients with asthma were classified with severe persistent asthma.
- 40.9% of patients with severe persistent asthma had one or more exacerbation in the past 12 months.
The prevalence of severe persistent asthma among patients with asthma significantly ranges across the United States, from 19.6% in New Mexico to 31.9% in Alaska, according to a study published in Annals of Allergy, Asthma & Immunology.
Exacerbations, ED visits and hospitalizations, and corticosteroid and biologic use similarly varied, Yan Wang, PhD, senior manager, health economics, Amgen, and colleagues wrote.
Affecting approximately 25 million people in the United States, asthma is a complex respiratory disease, Wang told Healio.
“While it is well known that asthma prevalence and severity vary at the national level from county to county, less is known about state-by-state variability within the U.S.,” Wang said.
The researchers used real-world data to map the burden of asthma by region and by state, focusing on prevalence, severity, occurrence of exacerbations, asthma control status and medication use.
“Our overarching goal was to identify regional disparities and reveal unmet medical needs among asthma patients in the United States,” Wang said.
Study design, results
Using data from the IQVIA open-source longitudinal prescription and medical claims database as well as from the IQVIA PharMetrics Plus closed-claims database, the researchers identified 2,092,799 patients with asthma aged 12 years and older.
This cohort included 496,750 patients (23.7%) with severe persistent asthma (mean age, 50.4 years; 68.4% female). By region, the Southern United States had the highest proportion of asthma patients with severe persistent asthma at 37.4%.
“Importantly, we identified significant geographic heterogeneity across U.S. states,” Wang said.
Severe persistent asthma was most prevalent among patients with asthma in Alaska (31.9%), Nebraska (28.8%) and South Dakota (28.8%) and least prevalent in Florida (20.8%), Delaware (20.3%) and New Mexico (19.6%).
Insurance coverage included commercial providers (72.2%), Medicare (25.1%) and Medicaid (2.7%), with 21.8% treated by an allergist and/or a pulmonologist. Also, the researchers said, comorbidity was mild.
Medication use during the study period included systemic corticosteroids for any reason, not just for asthma, for 60.8% of those patients with severe persistent asthma, based on projections to census population.
This use included 57.1% who used oral corticosteroid (OCS) bursts in the 12 months before the index date and 55.6% who used them in the 12 months after the index date.
“Interestingly, we found considerable variation in the use of systemic corticosteroids, which have a well-defined and undesirable side-effect profile,” Wang said.
Rates were highest in Mississippi (71.7%), Louisiana (71.2%) and Alabama (70.2%) and lowest in Vermont (52%), Oregon (51.8%) and Alaska (49.1%).
Also, 2.3% used maintenance OCS in the 12 months before the index date and 3.2% who used them after, as well as 19.9% who used intravenous corticosteroids in the 12 months pre-index and 19% who used them in the 12 months post-index.
Additionally, during the 12 months after the index date, 23.2% had one exacerbation and 17.8% had two or more exacerbations, with a mean of two exacerbations per year for those patients who experienced them.
Rates of patients with severe persistent asthma who reported exacerbations in the 12 months following the index date were highest in Louisiana (45.6%), Oklahoma (45.4%) and Texas (44.7%) and lowest in Idaho (35.7%), Alaska (34.3%) and Vermont (34.2%).
The survey also found that 13.4% of patients visited the ED or were hospitalized at least once. Nevada (17.7%), Wisconsin (17.7%) and the District of Columbia (16.9%) had the highest rates, and Vermont (8.9%), Tennessee (8.4%) and North Carolina (7%) had the lowest.
For more than half of the patients, insurance claims classified their disease as uncontrolled (21.8%) or sub-optimally controlled (36.4%) severe persistent asthma. Rates of severe uncontrolled asthma ranged from 24% in Arizona and Louisiana, 23% in Hawaii and Texas and 22.9% in Michigan to 17% in Minnesota, 16.8% in Alaska and 16.5% in Vermont.
Further, 14.8% of patients with severe uncontrolled asthma used biologic therapy in the 12 months after the index date, or 15.6% based on projections to the census population.
Mississippi (27.9%), Tennessee (23.5%) and South Dakota (22.1%) led biologic use among these patients, with Ohio (10.2%), New Mexico (5.7%) and Hawaii (2.2%) reporting the least use.
Physicians took at least one blood eosinophil count for 15.6% of the patients with severe persistent asthma. Counts included less than 150 µL for 33.8%, 150 µL to less than 300 µL for 33.5%, and 300 µL or higher for 32.7%.
Also, physicians recorded at least one total IgE value for 2.1% of the patients with severe persistent asthma, with counts reaching less than 100 kU/L for 52.3% and 100 kU/L or higher for 47.7%. Counts additionally included 80.4% with less than 400 kU/L and 19.6% with 400 kU/L or higher.
Conclusions, next steps
“These results highlight the geographic diversity of disease control and unmet medical need among U.S. patients with severe asthma,” Wang said.
Although the reasons for these differences may include genetic and host factors, environmental exposures and social determinants of health, the researchers continued, determining these causes was beyond the scope of the study.
“In considering the driving factors for the geographic variations, we pointed out that they are likely multifold,” Wang said.
Environmental exposures may include meteorologic factors such as extremes of heat and humidity as well as exposure to pollution and allergens, which vary from location to location, she continued.
Social determinants of health may include poverty, access to health care professionals such as asthma subspecialists, and heath care coverage, Wang added.
“Given that our study is descriptive in nature and not designed to assess cause and effect, we were unable to attribute specific causes to the state-level differences, but such questions merit future research,” Wang said.
The researchers called for additional studies that may explain these differences. In the meanwhile, they have posted an interactive tool that physicians and other providers may use to explore the impact of asthma in their state.
“Our work confirms what many clinicians know from their own practical experience, namely that the burden of asthma varies dramatically from one location and community to the next,” Andrew W. Lindsley, MD-PhD, medical director, U.S. medical affairs, Amgen, told Healio.
Asthma’s complexity, the geodiversity of triggers, and the variability in how asthma care is provisioned from state to state drive this diversity, Lindsley continued.
“Given the critical role that environmental triggers play in asthma and that access to health care also varies from place to place, these data provide a useful tool for health care providers to map the burden of asthma in their communities,” Lindsley said.
“We hope that these results will provide support to diverse stakeholders in the U.S. health care ecosystem who may then target their health care resources, advocacy and clinical care towards areas disproportionately affected by severe asthma,” Lindsley said.
Perspective
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These findings are not surprising, but they are significant, as they highlight health care disparities from region to region. Practicing in New York City, we see these disparities every day. Even within the same city, different neighborhoods have completely different asthma control.
For example, the Bronx has some of the most severe and worst asthma in the country. Yet a 30-minute subway ride away in Manhattan, those rates drop significantly. Even 20 blocks within Manhattan can make a huge difference, when you compare the Upper East Side and Harlem.
Asthma is very much an external disease as much as an internal one, and one’s environment plays a huge role in asthma control and severity. Certain areas have higher quantities of allergens that trigger asthma, such as cockroaches, dust mites and mold.
Further, those same areas also have higher rates of pollution and carbon emissions, which affect asthma as well. Finally, those same areas have a lack of access to specialists, health insurance and other resources, including medical facilities.
On a practice level, being cognizant of these disparities can be helpful in deciding treatment plans that are more conducive to these environments. Also, doctors can help with patient education and connections with free resources in these areas.
Additionally, policymakers need to have programs in place for allergy sufferers and asthmatics to reduce exposure to allergens in home environments, as well as improve medication and treatment coverage in these areas. Measures should be taken for clean air and reducing pollution and carbon emissions as well.
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Camargo CA, et al. Ann Allergy Asthma Immunol. 2023;doi:10.1016/j.anai.2023.12.016.
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