EXPRESS: Peripheral eosinophilia and preserved ratio impaired spirometry (PRISm).

Preserved ratio impaired spirometry (PRISm) may be in the pre-stage of chronic obstructive pulmonary disease. However, little is known about peripheral eosinophils in PRISm. This study ultimately enrolled 7,301 community-dwelling participants aged 20 to 79 years without airflow obstruction. Participants were categorized based on spirometry into two groups: normal spirometry and PRISm. Peripheral eosinophilia is defined by peripheral eosinophil counts ≥300 cells/µL. Multivariable logistic regression model was employed to examine the association between peripheral eosinophil counts and PRISm, as appropriate. Among the community adults finally recruited, 9.43% of participants exhibited PRISm, while 90.57% exhibited normal spirometry. Compared with the normal spirometry population, PRISm participants had a higher prevalence of peripheral eosinophilia in individuals aged 40 to 79 years (27.41% vs. 21.37%, P=0.01), non-Hispanic Whites (29.22% vs. 21.32%, P=0.01), those with a body mass index of 18.5-<25 kg/m2 (25.01% vs. 16.75%, P=0.03), never smokers (23.47% vs. 18.65%, P=0.03), individuals without a history of asthma (26.81% vs. 20.67%, P<0.001), and those with FeNO levels <50 parts per billion (P<0.05). Multivariable regression analysis showed a significant association between participants with eosinophil counts ≥300 cells/µL and PRISm compared to those with counts <150 cells/µL, with an adjusted odds ratio of 1.39 (95% CI: 1.12, 1.72). Peripheral eosinophilia was associated with PRISm in individuals without airflow obstruction. It is necessary to focus on the characteristics of peripheral eosinophils in this population.