Variation in inpatient investigations and treatment practices for COPD exacerbations between respiratory and internal medicine specialties: a retrospective cohort study.

Introduction: Chronic obstructive pulmonary disease (COPD) exacerbations are a major cause of hospitalization and healthcare utilization. The impact of inpatient specialty allocation on management practices remains unclear. This study examined variation in investigations and treatment practices among COPD patients admitted under respiratory medicine (RM) compared with internal medicine (IM), and evaluated clinical characteristics associated with RM admission. Methods: We conducted a retrospective cohort study of adults aged ≥40 years admitted for COPD exacerbations between January 2017 and March 2025. Patients were identified using ICD-10 COPD codes, excluding those admitted directly to ICUs or with asthma or bronchiectasis. Demographics, comorbidities, investigations, treatments, and hospitalization outcomes were analyzed. The primary outcome was variation in investigations and treatment practices between RM and IM admissions. The secondary outcome was identification of clinical characteristics associated with RM admission using multivariable logistic regression. Results: Among 6,277 COPD admissions, 3,211 (51.2%) were under RM and 3,066 (48.8%) under IM. Patients admitted under RM were younger (73.2 ± 10.7 vs. 75.6 ± 10.8 years, Conclusion: Variation in investigations and treatment practices was observed between RM and IM admissions for COPD exacerbations. These differences likely reflect variation in patient characteristics, illness severity, and clinical workflows rather than differences in quality of care attributable to specialty alone.