Abstract Rationale Asthma is a heterogeneous disease with multiple phenotypes. Preserved ratio impaired spirometry (PRISm), defined by reduced FEV₁ in the presence of a preserved FEV₁/FVC ratio, has been increasingly recognised due to its association with symptoms, comorbidities, and mortality in population-based cohorts. However, the impact of PRISm on asthma pathophysiology and clinical outcomes remains poorly understood. We hypothesised that PRISm in asthma constitutes a distinct clinical phenotype with unique characteristics and exacerbation risk. This study aimed to investigate the clinical features of patients with asthma and PRISm. Methods We conducted a retrospective analysis using a database of adult patients with asthma. Patients were categorised into three groups: those with normal %FEV1 and FEV1/FVC (CONT, %FEV1 ≥ 80% and FEV1/FVC ≥ 70%), those with a PRISm (PRISm, %FEV1 80% and FEV1/FVC ≥ 70%), and those with an obstructive ventilatory impairment (OBST, %FEV1 80% and FEV1/FVC 70%). Demographic data, asthma severity, pulmonary function, exacerbation history, and laboratory findings were collected. Continuous variables were compared using the Kruskal-Wallis test followed by Dunn’s post-hoc test. Categorical variables were analysed using chi-square tests. Multinomial logistic regression analysis was performed to identify factors independently associated with PRISm. Results Of the 1,411 patients, 1,102 were classified as the CONT group, 133 as the PRISm group, and 176 as the OBST group. Statistically significant differences were observed among the three groups in age, sex, smoking status, body mass index (BMI), asthma duration, severity of asthma, frequency of severe acute exacerbations and pulmonary function parameters. Post-hoc analysis showed that patients in the PRISm group had higher body mass index (BMI), greater proportion of severe asthma, more frequent severe exacerbations, and lower %FEF75 than those in the CONT group. When compared with the OBST group, the PRISm group had a shorter disease duration, yet the frequency of severe exacerbations was similar between the two groups. In multivariable analyses, higher BMI, reduced %FEF75 and more frequent severe exacerbations were independently associated with PRISm compared with the CONT group. Compared with the OBST group, PRISm was associated with higher BMI, shorter asthma duration and higher %FEF75. Conclusion Asthma with PRISm represents a distinct clinical phenotype characterised by obesity and increased exacerbation risk. Recognition of PRISm in asthma may facilitate targeted interventions to prevent exacerbations and disease progression. This abstract is funded by: None
To et al. (Fri,) studied this question.