Geographical variability in severe asthma: comparison of patients' characteristics between national, regional, and international cohorts in ISAR.

OBJECTIVE

The objective of this study is to describe and compare the clinical characteristics, treatment approaches, and associated comorbidities of patients with severe asthma across Greece, Southern Europe, and the global population. This comparative approach aims to enhance the understanding of region-specific differences and similarities among patients living with severe asthma.

METHODS

Data from the International Severe Asthma Registry (ISAR) were analyzed across three cohorts: Greek, Southern European, and Global. Variables included demographics, baseline characteristics, age at asthma onset, medication use, lung function, exacerbation history, biomarkers, and comorbidities.

RESULTS

A total of 16,063 patients from the global ISAR dataset, 3406 from Southern Europe, and 206 from Greece were included. Greek patients had a lower mean annual exacerbation rate (1.24 ± 1.67) compared with the global cohort (1.84 ± 2.58, p = 0.001) and Southern Europe (1.73 ± 2.56, p = 0.052). Uncontrolled asthma was most prevalent in Greece (60.32%) versus Southern Europe (35.58%, p < 0.001) and the global cohort (57.07%, p = 0.034). Long-term oral corticosteroid use was less frequent in Greece (24.73%) and in global cohort (21.50%, p = 0.287) than in Southern Europe (52.04%, p < 0.001). The prevalence of eosinophilic phenotype was high in all cohorts. However, in Greece, it was lower compared to Southern Europe (73.55% vs. 89.89% p < 0.001) and globally (73.55% vs. 83.34%, p = 0.011). Greek patients also demonstrated lower fractional exhaled nitric oxide (FeNO) levels and lower eosinophil counts than Southern Europe, along with reduced biologic therapy initiation (56.31%) compared to Southern Europe (74.02%, p < 0.001) but higher than global rates (48.40%, p = 0.024).

CONCLUSIONS

Regional differences in severe asthma underline the importance of tailored treatment approaches, and multidisciplinary management of comorbid conditions.