Prevalence of airflow limitation in subjects undergoing comprehensive health examination in Japan: Survey of Chronic Obstructive pulmonary disease Patients Epidemiology in Japan

Abstract

Purpose

There are still evidence gaps on the prevalence of airflow limitation in Japan. The purpose of this survey was to estimate the prevalence of airflow limitation among healthy subjects in Japan and to show what proportion of subjects with airflow limitation had been diagnosed with chronic obstructive pulmonary disease (COPD).

Subjects and methods

This was an observational, cross-sectional survey targeting multiple regions of Japan. Subjects aged 40 years or above who were undergoing comprehensive health examination were recruited from 14 centers in Japan. Airflow limitation was defined as having forced expiratory volume in 1 second/forced vital capacity less than 70%.

Results

In a total of 22,293 subjects, airflow limitation was most prevalent in subjects aged over 60 years (8.7%), but was also observed in subjects aged 50–59 years (3.1%) and 40–49 years (1.7%). Overall prevalence was 4.3%. Among subjects with smoking history (n=10,981), the prevalence of airflow limitation in each age group (12.8% in those aged over 60 years, 4.4% in those aged 50–59 years, and 2.2% in those aged 40–49 years) and overall prevalence (6.1%) were higher than that of total subjects. Of the smokers with airflow limitation, 9.4% had been diagnosed with COPD/emphysema and 27.3% with other respiratory diseases.

Conclusion

Among smokers undergoing comprehensive health examination, prevalence of airflow limitation reached 12.8% in those aged over 60 years and airflow limitation was observed in subjects aged 40–59 years as well, though their prevalence was lower than that in subjects aged over 60 years. We demonstrated that a significant proportion of smokers with airflow limitation had not been diagnosed with COPD/emphysema, suggesting that some of them can be diagnosed with COPD or other respiratory diseases by a detailed examination after comprehensive health examination. Screening for subjects at risk of COPD by spirometry in comprehensive health examination starting at 40 years of age, followed by a detailed examination, may be an effective approach to increase the diagnosis of COPD.

Keywords:

• spirometry
• lung function
• screening
• smoking
• general population

Acknowledgments

The authors are grateful to the people who participated in this survey and the staff in the medical institutions who contributed to this survey. The following investigators took part in data collection of this survey: Dr Takeshi Nawa (Hitachi General Hospital, Hitachi Ltd.), Dr Kazuhiro Gotou (Health Park Clinic Kurosawa), Dr Takashi Nakagawa (Omiya City Clinic), Dr Koji Yamashita (Yotsukaido Tokushukai Hospital), Dr Tatsuo Morikawa (Tokyo-Nishi Tokushukai Hospital), Dr Takayuki Kashiwabara (JA Shizuoka Kohseiren Enshu Hospital), Dr Tatsuya Shiraki (Matsubara Tokushukai Hospital), Dr Ryo Kobayashi (Bell Clinic), Dr Hiroshi Sonobe (Chugoku Central Hospital), Dr Toshiki Fukui (Center for Preventive Medical Treatment, NTT West Takamatsu Hospital), Dr Tokuji Motoki (Kochi Kenshin Clinic), Dr Yasuhiro Ogata, Dr Noritaka Higashi (Japanese Red Cross Kumamoto Healthcare Center), Dr Junko Aburaya (Koga Kenshin Center, Koga Ekimae Clinic), and Dr Koki Ido (Osumi Kanoya Hospital).

Editorial support in the form of development of the initial draft, collating author comments, editorial suggestions to draft versions of this paper, assembling tables and figures, copyediting, and referencing was provided by Diana Jones of Cambrian Clinical Associates Ltd. (Cardiff, UK) and was funded by GlaxoSmithKline.

Author contributions

All authors participated in the design and interpretation of this survey and the development of this manuscript. All authors had full access to the data and gave final approval before submission.

Disclosure

The authors report no conflicts of interest in this work.