Predictors of mortality and hospitalised exacerbations in obstructive airway diseases.

Background: In Belgium, age-standardised hospital admission and mortality rates for asthma and COPD are higher than the European average. Understanding the factors that lead to a hospitalised exacerbation and/or mortality is needed to optimise patient management. Methods: Patients ≥18 years old obtaining two claims for drugs for obstructive airway diseases (ATC code R03) in 1 year between 2017 and 2022 were identified in Belgian nationwide claims-based data. A multivariable Cox model was used to investigate predictors of all-cause mortality and hospitalised exacerbation. Results: Among 1 006 968 patients included in this study, 39 214 patients (3.9%) had a hospitalised exacerbation during follow-up and 145 021 patients (14.4%) died. Next to age, sex, Charlson comorbidity index and socioeconomic status, significant predictors for mortality were being frail (adjusted hazard ratio (aHR) 2.09, 95% confidence interval (CI) 2.06-2.12), heavy overuse of short-acting bronchodilators (SABDs) (≥6 packages per year, aHR 1.81, 95% CI 1.78-1.84), current smoking (aHR 1.64, 95% CI 1.61-1.66) and a history of ≥2 outpatient exacerbations in the previous year (aHR 1.52, 95% CI 1.49-1.54). A recent hospitalised exacerbation (aHR 5.67, 95% CI 5.51-5.84), current smoking (aHR 3.69, 95% CI 3.60-3.78), heavy overuse of SABDs (aHR 3.15, 95%CI 3.08-3.23) and being frail (aHR 1.07, 95% CI 1.03-1.10) were important additional risk factors for hospitalised exacerbation. Conclusion: Previous exacerbations, current smoking, frailty and overuse of SABDs were significantly associated with hospitalised exacerbations and mortality in patients with asthma and/or COPD. The results of this nationwide cohort study highlight the importance of achieving disease control, smoking prevention and tackling frailty in primary care.