Year-to-year trajectories of hospital utilisation rates among patients with COPD: a real-world, single-centre, retrospective cohort study

OBJECTIVES: The long-term clinical trajectory of chronic obstructive pulmonary disease (COPD) in terms of year-to-year hospital utilisation rates can be highly variable and is not well studied. We investigated year-to-year trends of hospitalisation or emergency department (ED) visits among patients with COPD over 3 years, identified distinct trajectories and examined associated predictive factors. DESIGN: A retrospective cohort study. SETTING: Data were extracted from the Changi General Hospital, Singapore COPD data warehouse. PARTICIPANTS: Patients with COPD aged ≥40 years with 3 years of follow-up data. PRIMARY AND SECONDARY OUTCOME MEASURES: The yearly rates of hospitalisations or ED visits, stratified by COPD-related or all-cause, were described. Group-based trajectory modelling was used to identify clinically distinct trajectories year-by-year. Baseline predictive factors associated with different trajectories were examined. RESULTS: In total, 396 patients were analysed (median age 70 years; 87% male). Four trajectories were generated for year-to-year trends in COPD-related hospitalisations/ED visits (C1–C4: consistently frequent, consistently infrequent, improving and worsening); post-bronchodilator forced expiratory volume in 1 second (FEV(1)) was a significant predictor of trajectory, with worse lung function being the main factor associated with less favourable trajectories. For all-cause hospitalisations/ED visits, four trajectories were identified (A1–A4: infrequent and stable, frequent and stable, frequent and decreasing, frequent and increasing); significant differences in age (p=0.041), sex (p=0.016) and ethnicity (p=0.005) were found between trajectories. Higher overall comorbidity burden was a key determinant in less favourable trajectories of all-cause hospitalisations/ED visits. CONCLUSIONS: Distinct trajectories were demonstrated for hospitalisations/ED visits related to COPD or all causes, with predictive associations between FEV(1) and COPD trajectory and between comorbidities and all-cause trajectory. Trajectories carry nuanced prognostic information and may be useful for clinical risk stratification to identify high-risk individuals for preventative treatments.