Coexisting COPD Increases Mortality in Patients With More Severe Asthma

Chronic obstructive pulmonary disease (COPD) was linked with greater all-cause mortality and greater risk of mortality in patients with coexisting asthma who also had long-term use of corticosteroids (CS), according to a study publishing in September in Allergy, Asthma & Immunology Research.

The population-based retrospective cohort study, conducted using health records in the Republic of Korea, was undertaken to identify the impact of coexisting COPD on long-term mortality in patients whose asthma control was dependent on chronic CS use.

Patients with CS-dependent asthma are considered to have the most severe forms of the lung disease, the researchers said; 20% to 60% of patients with severe asthma regularly use CS.

Asthma-COPD overlap syndrome (ACOS) is when an individual presents symptoms and characteristics of both asthma and COPD. Its health burden is believed to be greater than either asthma or COPD alone.

The researchers said that globally, the proportion of COPD among patients with asthma is reportedly up to 50%. The comorbidities of the 2 diseases are linked with reduced quality of life and increased health care utilization.

Using records from the Korean National Health Insurance Service database for 2005 to 2015, the researchers included adults 40 years or older with CS-dependent asthma, for a total of 8021 patients. Patients were divided into 2 groups according to the presence of COPD, and the authors evaluated the hazard ratio (HR) for all-cause mortality in patients with COPD relative to those without COPD. Results were adjusted for the effect of age, sex, type of insurance, and Charlson comorbidity index (CCI) using the multivariable Cox proportional regression model.

Asthma was defined as 1 or more claims for the use of asthma-related drugs, such as inhaled or systemic CS medication, bronchodilators, leukotriene receptor antagonists, and xanthine derivatives (ie, theophylline) during the baseline period (12 months after the diagnosis of asthma between January 1 and December 31, 2005).

CS-dependent asthma was defined as the presence of asthma and prescription of systemic CS under International Classification of Diseases, 10th Edition, codes for at least 6 months during the baseline period. Likewise, COPD was defined by at least 1 claim during the baseline period.

Results showed:

• Out of 8021 patients with CS-dependent asthma, 3121 (38.9%) had COPD.
• The top 3 causes of death in patients with CS-dependent asthma was respiratory (44.1%), followed by cardiovascular (16.8%) and malignancy (13.5%).
• All-cause mortality was significantly greater in patients with CS-dependent asthma and COPD than in those without COPD (9955/100,000 person-years [PY] vs 5585/100,100 PY; P < .001).

The adjusted HRs were 1.29 (95% CI, 1.21-1.38), and the associations were especially significant for chronic lower respiratory diseases and lung cancer:

• Mortality for chronic lower respiratory diseases (including asthma, bronchiectasis, and COPD) subdistribution HR, 2.30 (95% CI, 2.06-2.57)
• Lung cancer subdistribution HR, 1.34 (95% CI, 1.02-1.78)

The authors said the results show the importance of knowing the cause of death in order to determine prevention strategies. They said additional studies are needed to see if early diagnosis and management of coexisting COPD might prevent worse outcomes in patients with severe asthma.

Reference

Lee H, Ryu J, Chung SJ, et al. Coexisting COPD increases mortality in patients with corticosteroid-dependent asthma: a nationwide population-based study. Allergy Asthma Immunol Res. 2020;12(5):821-831. doi:10.4168/aair.2020.12.5.821