Asthma with Preserved Ratio Impaired Spirometry Linked to High Exacerbation Risk: Study
Written By : Medha Baranwal
Medically Reviewed By : Dr. Kamal Kant Kohli
Published On 2026-09-13 15:00 GMT | Update On 2026-09-13 15:01 GMT
Japan: Patients with asthma and Preserved Ratio Impaired Spirometry (PRISm) experience more than twice the rate of severe acute exacerbations compared with those who have normal lung function, a new study revealed. Importantly, their exacerbation burden is similar to that of patients with obstructive ventilatory defects, despite the absence of clear airflow obstruction.
These findings, published in the Journal of Asthma and Allergy, suggest that PRISm identifies a high-risk asthma subgroup that may require closer monitoring and more intensive management to prevent severe attacks.
Asthma is a complex disease with multiple clinical phenotypes, making it important to identify patient groups at greater risk of poor outcomes. Although PRISm has previously been associated with adverse health consequences in the general population, its clinical significance in asthma has remained unclear. To address this gap, Yoshihito Arimoto from the Department of Laboratory Medicine, Dokkyo Medical University, Saitama Medical Center, Japan, and colleagues investigated whether asthma with PRISm represents a distinct phenotype linked to an increased burden of exacerbations.
The researchers retrospectively analyzed data from 1,411 adults with asthma. Based on lung function parameters, participants were divided into three groups: a control group with normal lung function (1,102 patients), a PRISm group (133 patients), and an airflow obstruction group (176 patients). Clinical characteristics, disease severity, and exacerbation profiles were compared across the three groups.
Key findings from the study include:
- Significant differences in age, sex, smoking status, and body mass index (BMI) were observed across the three study groups.
- Patients with asthma and PRISm had a significantly higher rate of severe acute exacerbations than those with normal lung function.
- The frequency of severe exacerbations in the PRISm group was comparable to that in patients with airflow obstruction.
- Severe asthma was more common in the PRISm group than in the control group, but occurred at a rate similar to that in the airflow obstruction group.
- Compared with the control group, patients with PRISm were more likely to have a higher BMI, a longer duration of asthma, and more than twice the risk of severe acute exacerbations.
- Compared with patients with airflow obstruction, those with PRISm had a higher BMI and a shorter duration of asthma. At the same time, the risk of severe acute exacerbations remained similar between the two groups.
The researchers noted that the retrospective, single-center design involving only Japanese patients may limit the generalizability of the findings. They also acknowledged that defining PRISm using a single spirometry assessment and the inability to account for treatment intensity may have resulted in misclassification and residual confounding.
Overall, the findings suggest that asthma with coexisting PRISm is a distinct, clinically important phenotype associated with a high burden of severe exacerbations. Early recognition of these patients may support closer monitoring and timely optimization of asthma management. The researchers called for larger prospective and mechanistic studies to clarify the biological basis and long-term clinical course of this phenotype.
Reference:
Arimoto Y, Honda N, Haruki K, To Y, To M. Asthma with Preserved Ratio Impaired Spirometry: A Distinct Phenotype Associated with Increased Exacerbation Burden. J Asthma Allergy. 2026;19:618426. https://doi.org/10.2147/JAA.S618426
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