Chest
Volume 126, Issue 4, October 2004, Pages 1234-1240
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Clinical Investigations
PULMONARY FUNCTION
Respiratory Symptoms and Undiagnosed Airflow Obstruction in Middle-Aged Adults: The Korean Health and Genome Study

https://doi.org/10.1378/chest.126.4.1234Get rights and content

Background:

The prevalence of undiagnosed airflow obstruction is difficult to measure since it requires screening in population-based samples to identify individuals free of clinical symptoms. The purpose of this report is to examine the prevalence of undiagnosed airflow obstruction and its relation with respiratory symptoms in middle-age adults in the Korean Health and Genome (KHG) Study.

Methods:

The KHG study is an ongoing population-based study of Korean adults aged 40 to 69 years. The current report includes 8,140 men and women without a pulmonary disorder or obstructive lung disease. In this sample, undiagnosed airflow obstruction was defined on the basis of spirometric testing and in the absence of a medical history or a recognized pulmonary disorder. Respiratory symptoms included chronic cough, chronic phlegm, wheezing, and shortness of breath.

Results:

Undiagnosed airflow obstruction was observed in 12.4% of the men (470 of 3,806 subjects) and in 3.5% of the women (152 of 4,334 subjects). In men, the age-adjusted prevalence of undiagnosed airflow obstruction increased consistently with increasing number of respiratory symptoms. In those who smoked, there was a 2.3-fold excess in its prevalence when three or more symptoms were present, as compared to when they were absent (27.4% vs 12.0%, p < 0.001). A 2.4-fold excess (20.6% vs 8.5%, p = 0.004) was observed in nonsmoking men, in whom respiratory symptoms were consistently less common than in those who smoked. Respiratory symptoms were unrelated to undiagnosed airflow obstruction in women smokers, although only 3.9% smoked cigarettes. In women who were nonsmokers, the prevalence of undiagnosed airflow obstruction increased from 2.3% in those without a respiratory symptom to 6.0% when three or more symptoms were present (p = 0.003).

Conclusions:

Findings suggest that undiagnosed airflow obstruction is common in Korea with several respiratory symptoms. Whether respiratory symptoms with associations with undiagnosed airflow obstruction can be used to design early intervention strategies that prevent or delay the onset of COPD and its disabling consequences warrants further study.

Section snippets

Background

The Korean Health and Genome (KHG) Study began in 2001 as an ongoing population-based study of Korean adults aged 40 to 69 years. Support for the study is from the National Genome Research Institute, as an effort to describe the frequency and determinants of chronic diseases in Korea. Participants include residents of an urban community 32 kilometers southwest of Seoul, South Korea (Ansan), and in a rural setting 100 kilometers south of Seoul (Ansung). Procedures were in accordance with

Results

Undiagnosed airflow obstruction was observed in 12.4% of the men (470 of 3,806 subjects) and in 3.5% of the women (152 of 4,334 subjects). Tables 1, 2present the overall prevalence of each respiratory symptom within 10-year age groups, and according to smoking status in men and women, respectively. Among the respiratory symptoms, those that were the most common included chronic phlegm, wheezing, shortness of breath, and shortness of breath at rest and when walking uphill.

In men who smoked

Discussion

Findings from the present study suggest that respiratory symptoms are common in middle-aged men and women in Korea. Increases in the prevalence of undiagnosed airflow obstruction with advancing age are also substantial. Among the respiratory symptoms associated with undiagnosed airflow obstruction, wheezing seemed to be the most important, followed by shortness of breath under various conditions and chronic cough. The prevalence of undiagnosed airflow obstruction also increased as the number of

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    Supported by a grant (348–6111-221) from the Korean National Institute of Health.

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