Coexisting Respiratory Comorbidities Increase Mortality in Patients with
Asthma: A National Cohort Study
Abstract
Background: Asthmatic patients are generally considered to have an
increased risk of mortality compared with subjects without asthma.
However, this issue has not been fully evaluated using nationally
representative data. In addition, it is unclear whether respiratory
comorbidities other than chronic obstructive pulmonary disease (COPD)
are associated with increased mortality in asthmatic patients compared
with subjects without asthma. Methods: Using a nationally representative
sample database, we performed a retrospective cohort study of patients
with asthma and age- sex-matched control cohort. We estimated hazard
ratio (HR) and 95% confidence interval (CI) for mortality. We also
stratified the asthma cohort based on respiratory comorbidities.
Results: During a median 8.9-year follow-up, the overall mortality rate
was higher in the asthma cohort than in the control cohort (p
< 0.001). The HR for mortality in the asthma cohort compared
with the control cohort was 1.13 (95% CI = 1.07–1.19). The effects of
asthma on mortality were more evident in males, patients under medical
aid, and subjects with COPD. Respiratory comorbidities were
significantly associated with increased risk of mortality in asthmatic
patients compared with controls (COPD, adjusted HR, aHR = 1.49, 95% CI
= 1.39–1.59; bronchiectasis, aHR = 1.43, 95% CI = 1.18–1.73; lung
cancer, aHR = 4.11, 95% CI = 2.59–6.52; pneumonia, aHR = 1.59, 95% CI
= 1.46–1.74). Conclusion: Patients with asthma had a higher mortality
rate compared with subjects without asthma. Coexisting pulmonary
comorbidities were the primary cause of higher mortality in patients
with asthma