Prevalence of airflow limitation in outpatients with cardiovascular diseases in Japan

Abstract

Background and objectives

Cardiovascular disease (CVD) and chronic obstructive pulmonary disease (COPD) commonly coexist and share common risk factors. The prevalence of COPD in outpatients with a smoking history and CVD in Japan is unknown. The aim of this study was to determine the proportion of Japanese patients with a smoking history being treated for CVD who have concurrent airflow limitation compatible with COPD. A secondary objective was to test whether the usage of lung function tests performed in the clinic influenced the diagnosis rate of COPD in the patients identified with airflow limitation.

Methods

In a multicenter observational prospective study conducted at 17 centers across Japan, the prevalence of airflow limitation compatible with COPD (defined as forced expiratory volume (FEV)₁/FEV₆ <0.73, by handheld spirometry) was investigated in cardiac outpatients ≥40 years old with a smoking history who routinely visited the clinic for their CVD. Each patient completed the COPD Assessment Test prior to spirometry testing.

Results

Data were available for 995 patients with a mean age of 66.6±10.0 years, of whom 95.5% were male. The prevalence of airflow limitation compatible with COPD was 27.0% (n=269), and 87.7% of those patients (n=236) did not have a prior diagnosis of COPD. The prevalence of previously diagnosed airflow limitation was higher in sites with higher usage of lung function testing (14.0%, 15.2% respectively) compared against sites where it is performed seldom (11.1%), but was still low.

Conclusion

The prevalence of airflow limitation in this study indicates that a quarter of outpatients with CVD have COPD, almost all of whom are undiagnosed. This suggests that it is important to look routinely for COPD in CVD outpatients.

Keywords:

• COPD
• CVD
• handheld spirometer
• lung function
• diagnosis

Acknowledgments

The authors are grateful to the 17 medical institutes and investigators who participated in this study: Kazufumi Takeuchi (Chugoku Central Hospital); Yutaka Kajikawa (NHO Fukuyama Medical Center); Yasushi Terada (Shonai Amarume Hospital); Nobuaki Shinozaki (Shonan Atsugi Hospital); Hiroshi Shudo (Hiro Internal and Cardiology Clinic); Kenshi Fujii (Sakurabashi Watanabe Hospital); Atsuyuki Wada (Kusatsu General Hospital); Yoshihiko Araki (Osaka Prefectural Medical Center for Respiratory and Allergic Diseases); Akinori Hashimoto (Hashimoto Internal Clinic); Toshiyuki Goto (Goto Internal Clinic); Takaaki Kato (Kato Internal Clinic); Toshiaki Kadokami (Futsukaichi Hospital); Kunihiko Ueda (Ueda Internal and Cardiology Clinic); Kazuki Nakajima (Nakajima Cardiology and Internal Clinic); Shinya Okamoto (Iwasaki Hospital); Takahiro Yazu (Yazu Internal Clinic). The authors are also grateful to the Center for Clinical Trials, Japan Medical Association, and to all teams of GSK for their contribution to this study. The authors thank Diana Jones (Cambrian Clinical Associates Limited, Cardiff, UK) for medical writing and manuscript coordination, which was funded by the study sponsor.

Disclosure

The study has been funded, planned, and prepared by GlaxoSmithKline KK (GSK), who also drafted this manuscript for publishing. All authors had final responsibility for manuscript submission.

Katsuya Onishi discloses no conflict of interest. Paul W Jones discloses that his university has received honoraria and research grants from the commercial entity that sponsored the study. Gerry W Hagan discloses having received consultancy fee from GSK and reports ownership of GSK stock options. Daisuke Yoshimoto is an employee of GSK and reports ownership of GSK stock options.