Coexisting COPD in elderly asthma with fixed airflow limitation: Assessment by DLco %predicted and HRCT

ABSTRACT

Background: Asthma patients with fixed airflow limitation (FL) are theoretically classified into two phenotypes, that is, coexisting chronic obstructive pulmonary disease (COPD) and asthmatic airway remodeling. However, the precise percentages of such patients are not known. Objective: To assess the prevalence of patients with both FL and COPD components in elderly asthma. Methods: We evaluated patients by lung diffusion impairment and emphysematous findings in high-resolution computed tomography (HRCT) as candidates for COPD components, as a multicenter, cross-sectional survey. Asthma outpatients ≥ 50 years of age were enrolled from Tohoku University Hospital, Sendai, Japan, and four hospitals (Tohoku Medical and Pharmaceutical University Wakabayashi Hospital, Sendai, JAPAN; Wakayama Medical University Hospital, Kimiidera, Japan; Hiraka General Hospital, Yokote, Japan; Iwate Prefectural Isawa Hospital, Oshu, Japan) with pulmonary physicians from March 1, 2013 to November 30, 2014. Results: The prevalence of patients with FEV₁/FVC <70% was 31.0% of those in their 50s, 40.2% of those in their 60s and 61.9% of those in their 70s or older. The prevalence of those patients with lung diffusion impairment (i.e. the percent predicted values of diffusing capacity of the lung for carbon monoxide (DLco %predicted) <80%) or emphysematous findings in HRCT (i.e. the appearance of low attenuation area (LAA)) was 18.3% of those in their 50s, 13.8% of those in their 60s and 35.7% of those in their 70s or older. Conclusions: Nearly half of the patients with FL in elderly asthma show coexisting COPD components when assessed by DLco %predicted and LAA in HRCT.

KEYWORDS:

• ACOS
• COPD
• diffusion impairment
• LAA

Acknowledgement

The authors gratefully acknowledge Mr. Brent K. Bell for reading the manuscript.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Funding

This work was supported by Grant-in-Aid for Scientific Research No. 15K09207 (to T. Tamada) from The Ministry of Education, Science, Sports and Culture, Japan, and a grant (to K. Ohta) from the Environmental Restoration and Conservation Agency of Japan. The Practical Research Project for Allergic Diseases and Immunology (Research on Allergic Diseases and Immunology) No. 16ek0410018h0002 and No. 16ek0410036h0001 (to M. Ichinose) from Japan Agency for Medical Research and Development, AMED.