Stability of Type 2 Inflammation in a 12-Year Adult-Onset Asthma Follow-Up Study

Purpose: To assess the stability of T2 inflammation and clinical features associated with high or low T2 markers in adult-onset asthma. Patients and Methods: Seinäjoki Adult Asthma Study is a 12-year follow-up study including 256 patients diagnosed with new-onset adult asthma. Patients were grouped according to T2 marker status at baseline when steroid-naïve and at the 12-year follow-up after long-term inhaled corticosteroid (ICS) treatment. High T2 markers were defined at diagnosis by ≥ 1 of the following: blood eosinophils ≥ 0.30× 10 9 /L or positive SPT, and at follow-up by ≥ 1 of the following: blood eosinophils ≥ 0.30× 10 9 /L, FeNO ≥ 25 ppb, or specific IgE ≥ 0.3 ISU. Results: At diagnosis, 109 patients (66.5%) had high and 55 (33.5%) low T2 markers. Low T2 marker patients were older, had higher BMI, and higher Airway Questionnaire 20 scores. High T2 marker patients had greater reversibility of forced expiratory volume in 1 second. At follow-up, baseline low T2 marker patients had more comorbidities, non-respiratory medications and lower Asthma Control Test scores. Of patients, 76% remained in the low T2 marker group and 24% transitioned to the high T2 marker group; those who transitioned had higher BMI. Sixty-eight percent remained in the high T2 marker group and 32% transitioned to the low T2 marker group; those who transitioned were older, had more comorbidities, and more non-respiratory medications. No significant differences were observed between patients who transitioned and those remaining stable regarding lung function, asthma severity, control, exacerbations, or ICS use. Conclusion: T2 high and low markers of adult-onset asthma are largely stable over time. However, differences in comorbidities, non-respiratory medication, age, and BMI distinguish the groups significantly. Keywords: adult-onset asthma, endotype, phenotype, type 2 inflammation