Non-elderly asthma phenotypes and blood eosinophils are associated with clinical outcomes in elderly asthma

The number of patients with elderly asthma (EA) is increasing with global population aging. EA differs from non-elderly asthma (NEA) in clinical characteristics and underlying pathophysiology, but it remains unclear which factors before older age are associated with clinical outcomes in older age. This study investigated NEA factors associated with subsequent EA outcomes and phenotype transitions. This multicenter retrospective observational cohort study enrolled 82 patients with EA (≥ 65 years) and collected their earliest available clinical data obtained during the NEA period (< 65 years). Clinical assessments included pulmonary function tests, blood biomarkers, and patient-reported outcomes. Patients were classified into three EA (EA1-EA3) and three NEA clusters (NEA1-NEA3) using a previously established decision tree model. Logistic regression was used to identify NEA factors associated with clinical remission in EA. In addition, correlations between NEA biomarkers and percent forced expiratory volume in 1 s (%FEV1) in EA were calculated. Higher blood eosinophil counts during the NEA period were associated with a lower likelihood of clinical remission in EA, under both 3-way (odds ratio [OR] 0.871 per 100/µL) and 4-way (OR 0.839 per 100/µL) definitions, adjusted for sex and body mass index. Among preceding phenotypes, patients classified as NEA2 (long disease duration with eosinophilic features) showed poorer EA outcomes, including more frequent oral corticosteroid use and lower rates of clinical remission. Both peripheral blood eosinophil counts and total serum immunoglobulin E (IgE) levels during the NEA period negatively correlated with %FEV1 during the EA period. Higher blood eosinophil counts before older age were linked to poorer asthma outcomes after older age, suggesting that persistent eosinophilic inflammation earlier in adulthood may be associated with unfavorable outcomes later in life.