Underdiagnosis of COPD: The Japan COPD Real-World Data Epidemiological (CORE) Study

Abstract

Purpose

The prevalence of airflow obstruction in Japan is 3.8%–16.9%. This epidemiological study based on a large database aimed to reassess the prevalence of airflow obstruction in Japan and the diagnosis rate of chronic obstructive pulmonary disease (COPD).

Patients and Methods

We used data regarding claims from the health insurance union and health checkups provided by JMDC. The present study included a subgroup of individuals aged ≥40 years who underwent health checkups involving spirometry between January and December 2019. The study endpoints were the prevalence of airflow obstruction, COPD diagnosis rate, disease stage, and respiratory function test results.

Results

Among 102,190 participants, 4113 (4.0%) had airflow obstruction. The prevalence of airflow obstruction was 5.3% in men and 2.1% in women. Among the study population, 6.8% were current smokers, while 3.4% were never or former smokers. Additionally, the prevalence of COPD increased with age. Approximately 8.4% of participants with airflow obstruction were diagnosed with COPD. Regarding the COPD diagnosis status, participants with airflow obstruction who were diagnosed with COPD were at a more advanced stage than those not diagnosed. Finally, patients diagnosed with COPD had significantly lower FEV₁/FVC and FEV₁ (p < 0.0001; Wilcoxon rank sum test).

Conclusion

The epidemiological study based on a large database determined the COPD diagnosis rate related to airflow obstruction. The COPD diagnosis rate was extremely low among individuals who underwent health checkups, indicating the need for increased awareness about this medical condition. Moreover, primary care physicians should identify patients with suspected COPD and collaborate with pulmonologists to facilitate the early detection of COPD and enhance the COPD diagnosis rate.

Keywords:

• COPD
• epidemiology
• airflow obstruction
• prevalence
• Japan
• real-world data

Abbreviations

COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in one second; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; MHLW, Ministry of Health, Labour and Welfare.

Author Contributions

YK, SD, TM, AS, YS, and HS made a significant contribution to the work reported, in the conception, study design, execution, and interpretation. GT and TT made a significant contribution in study design supporting, acquisition of data, analysis. All authors took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; agreed on the journal to which the article was submitted; and agreed to be accountable for all aspects of the work.

Disclosure

YK, SD, TM, and AS are employees of Kracie, Ltd. GT and TT are affiliated with JMDC Inc. YS and HS received personal fees from Kracie, Ltd. The authors report no other conflicts of interest in this work.

Additional information

Funding

This study was funded by Kracie, Ltd. The funder of the study had a role in study design, data interpretation, and writing of the report.