The effect of COPD exacerbation history on future exacerbation risk and mortality

BACKGROUND: The 2023 Global Initiative for Chronic Obstructive Lung Disease (GOLD) report classifies individuals with chronic obstructive pulmonary disease (COPD) who have experienced ≥2 moderate (outpatient) or ≥1 severe (emergency department or hospitalization) exacerbations within the last year as being at high risk of future exacerbation (category E). OBJECTIVES: This study aimed to investigate the risk of exacerbation and death associated with the individual components of the GOLD E category. METHODS: We conducted a retrospective cohort study using health administrative data from Ontario, Canada (2007-2018). Individuals ≥65 years of age with physician-diagnosed COPD were followed for up to 5 exacerbations, until their death, or the study period ended. After each exacerbation, individuals were assigned to 1 of 3 GOLD subgroups: E moderate (≥2 moderate), E severe (≥1 severe), and AB (≤1 moderate). Under a landmark analysis framework, Fine-Gray subdistribution hazards (sdHR) competing risk models were created for each event, and the risk of exacerbation and death was estimated. RESULTS: There were 279 798 individuals included. Individuals in the GOLD E moderate subgroup were at a higher risk of future exacerbation (COPD, chronic obstructive pulmonary disease exacerbations 3-5 = 1.16-1.23) and a lower risk of death (sdHR exacerbations 3-5 = 0.75-0.82) than GOLD AB individuals. In comparison, patients in the GOLD E severe subgroup were at lower risk of future exacerbation (sdHR exacerbations 2-5 = 0.89-0.95), but higher risk of death (sdHR exacerbations 2-5 = 1.56-1.59). CONCLUSIONS: These findings indicate that COPD patients in the GOLD E moderate subgroup have a different risk of future exacerbation and death than individuals in the GOLD E severe subgroup.