COPD in Japan: the Nippon COPD Epidemiology study

Authors


  • Part of this material has been previously presented as a poster at the 11th Annual Congress of the European Respiratory Society (ERS) held in Berlin, Germany, in September 2001. This abstract was printed in the Supplement of the European Respiratory Journal (Volume 18, Supplement 33). Some of the information included in the poster was subsequently cited in a summary article on worldwide epidemiology of COPD in ‘COPD Frontier’, which is a Japanese-language newsletter for physicians in Japan. The poster presentation and article in ‘COPD Frontier’ represented preliminary study results. The information presented in this article represents the final analysis of study data. This article has not otherwise been published and is not being considered for publication elsewhere.

Yoshinosuke Fukuchi, Department of Respiratory Medicine, Juntendo University, 2-1-1 Hongo Bunkyo-ku, Tokyo, Japan. Email: yfukuchi@med.juntendo.ac.jp

Abstract

Objectives:  Despite high smoking rates, few prevalence studies of COPD have been performed in Asia. The Nippon COPD Epidemiology (NICE) Study used spirometry to measure prevalence of airflow limitation in Japanese adults.

Methodology:  Clinical, spirometric, and risk factor exposure data were collected on 2343 subjects aged ≥ 40 years who were demographically similar to the Japanese population. Airflow limitation was defined according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria (FEV1/FVC < 70%).

Results:  Prevalence of airflow limitation was 10.9%. Based upon GOLD severity criteria, 56% of these cases were found to be mild, 38% moderate, 5% severe, and 1% very severe. Airflow limitation was significantly more prevalent in males than females (16.4% vs. 5.0%; P < 0.001), in male ever-smokers than female ever-smokers (17.1% vs. 7.5%; P < 0.001), and in older subjects (3.5% in 40–49 years olds vs. 24.4% in those > 70 years; P < 0.001). Of note, airflow limitation was also found in 5.8% of non-smokers and 4.6% of those younger than age 60 years. Only 9.4% of cases with airflow limitation reported a previous diagnosis of COPD.

Conclusions:  Prevalence of airflow limitation in Japan is higher than previously reported, suggesting a high degree of under-recognition of COPD. The high prevalence of smoking coupled with an aging population threatens to further increase the burden of COPD, highlighting the need for enhanced screening efforts and interventions of prevention and treatment.

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