A recent cohort study found that asthma exacerbations decreased significantly once respiratory biologics were introduced in rapid succession starting in 2015.1
Clinical trials and real-world studies have shown that biologics can substantially reduce asthma exacerbations in individual patients with moderate to severe asthma. However, it was unclear what measurable population-level improvements these therapies would produce.
To answer this question, investigators examined population-level trends in asthma exacerbations before and after 2015, when the number of available respiratory biologics began to expand rapidly. The results were recently published in JAMA Network Open.
The cohort study included 5,269 adults with physician-diagnosed asthma who received specialty allergy or pulmonary care within a large health care system in the Boston areafrom 2006 to 2025. The primary outcomes were changes in the intercept and slope of annual exacerbations per 1,000 asthma patients per year. Exacerbations were defined as worsening asthma requiring an emergency department visit, hospitalization, or a short course of oral corticosteroids. The study also examinedwhether trends differed by subgroup, including disease severity, eosinophil count, age, sex, BMI, smoking status, and insurance type.
From 2006 to 2015, annual exacerbation rates increased on average by 155.4 events per 1,000 patients per year. After 2015, annual exacerbation events immediately decreased by 474.1 events per 1,000 patients per year. This was followed by a sustained yearly decline of 206.5 events per 1,000 patients per year.
Patients who had the greatest burden of asthma before the biologics era experienced the greatest improvement afterward. As a result, the outcome gap between patients with severe and milder asthma narrowed substantially.
“That is important because severe asthma accounts for a disproportionate amount of asthma morbidity,” said Ayobami Akenroye, MBChB, MPH, PhD, Associate Professor of Medicine at Harvard Medical School and a physician-scientist at Brigham and Women’s Hospital. “The fact that the largest improvements occurred precisely in the groups most likely to receive and respond to biologics—patients with frequent exacerbations and eosinophilic disease—provides population-level evidence that the biologics era has coincided with meaningful improvements in asthma outcomes.”
Importantly, almost all subgroups (age, sex, BMI, insurance type) demonstrated great improvements after 2015. Annual exacerbation events also decreased across several demographic and clinical groups, including patients with blood eosinophil counts of 450 cells/μL or greater and those with comorbid COPD and chronic rhinosinusitis.
However, some disparities remained. For example, patients living in urban, low-income areas continued to have higher absolute exacerbation rates, even as their outcomes improved over time, suggesting clinicians can do more to maximize the value of these biologics.
“I think that the biggest limitation is access,” said Damaris E. Pena Evertz, MD, Director of the Severe Asthma Program at Thomas Jefferson University. “In this study, a significant proportion of patients had commercial insurance and likely had better access to biologic therapies. From my perspective, practicing in a setting where most of the patients have either Medicare or Medicaid, access can remain a challenge. There are barriers and hoops that we must jump through, but once we’re able to overcome them and the patients are able to start these therapies, it makes a huge difference. From when we started using biologics until now, that access barrier has improved to some extent.”
Going forward, Dr. Evertz said, she would like to see studies that directly link biologic initiation and reduced exacerbation rates to other clinically meaningful outcomes, including improved asthma control, quality of life, and fewer missed days of work. Replicating these findings in a more diverse, multicenter population could provide a more complete picture of the real-world impact of biologic therapy.
Dr. Akenroye outlined several important next steps. First, she said, because this study focused on a single health system with individuals who were predominantly privately insured, researchers need to replicate the findings in larger, more geographically and socioeconomically diverse populations. Second, patient-level studies should directly link biologic initiation to outcomes. This study deliberately examined population-level trends and therefore cannot establish that biologics alone caused the decline; other changes in asthma care also occurred during this period.
Finally, Dr. Akenroye said, future research should look beyond exacerbations and evaluate other outcomes, including lung function and patient-reported quality of life, which this analysis did not capture.
References
1. Tu YF, Stein DW, Akenroye A. Population-level trends in asthma exacerbations after introduction of respiratory biologics. JAMA Netw Open. 2026;9(6):e2620272. doi:10.1001/jamanetworkopen.2026.20272
