Clinical Disease Burden in Patients with Chronic Obstructive Pulmonary Disease and Type 2 Inflammation in Japan: A Retrospective Database Analysis (EUROS Study).

Purpose: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality globally. Preventing COPD exacerbations is a primary goal in disease management. A subset of patients with COPD exhibits type 2 inflammation (T2I), but the clinical implications of T2I in Japanese patients are not understood. Patients and Methods: We used a nationwide Japanese electronic medical records database to evaluate the clinical implications of T2I in COPD, focusing on COPD exacerbations and major adverse cardiovascular events (MACE). T2I was based on blood eosinophil counts and defined as low (<100 cells/μL), intermediate (100-300 cells/μL) or high (>300 cells/μL). Eosinophil counts were assessed from outpatient measurements during a 12-month baseline period, with the highest value used to define T2I status. The patients were identified during the study period from January 1, 2010, and September 30, 2023. Results: Of 10,321 eligible patients, 67.3% were male; the median age was 75.0 years. The adjusted incidence rate of combined moderate and severe COPD exacerbations was significantly higher in patients with high T2I compared with intermediate T2I (rate ratio [RR]: 1.16, 95% confidence interval [CI]: 1.08, 1.24). Exacerbation incidence was also higher in high versus low T2I (RR: 1.21, 95% CI: 1.08, 1.37). No statistically significant differences were observed in MACE incidence; compared with the intermediate T2I group, the adjusted rate of MACE was numerically lower in the low T2I group and higher in the high T2I group. Conclusion: T2I was associated primarily with an increased risk of moderate COPD exacerbations, a clinically meaningful driver of clinical burden and healthcare utilization in Japan. Cardiovascular analyses were underpowered. These findings highlight the potential clinical relevance of T2I for risk stratification in COPD and the need for further studies to refine eosinophil-based endotyping and clarify its implications for treatment response in this population.