Asymptomatic patients of chronic obstructive pulmonary disease in China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Chronic obstructive pulmonary disease (COPD) has a variable natural history and not all individuals follow the same course. This study aimed to identify the prevalence and characteristics of asymptomatic COPD patients from a population-based survey in China.</p><p><b>METHODS</b>A multistage cluster sampling strategy was used in a population from seven different provinces/cities. All residents (over 40 years old) were interviewed with a standardized questionnaire and spirometry. Post-bronchodilator forced expiratory volume in 1 second (FEV(1))/forced vital capacity (FVC) of less than 70% was defined as the diagnostic criterion of COPD. All COPD patients screened were divided into symptomatic group and asymptomatic group according to the presence or absence of chronic respiratory symptoms. Socio-demographic, personal and exposure variables were collected and analyzed.</p><p><b>RESULTS</b>Among the 1668 patients who were diagnosed with COPD from the 25 627 sampling subjects, 589 (35.3%) were asymptomatic. The age, sex, body mass index (BMI), rural and urban distributions, smoking habit and education levels were similar in the two groups. A total of 64.7% of the asymptomatic patients had no comorbidities. Cardiovascular diseases and lung cancer were more common among symptomatic COPD patients than asymptomatic group. Asymptomatic COPD group were less likely to present with poor ventilation in the kitchen, a family history of respiratory disease and recurrent childhood cough. Asymptomatic COPD patients had significantly higher FEV(1) (73.1% vs. 61.0%), FVC (91.9% vs. 82.0%), and a higher ratio of FEV(1)/FVC (62.9% vs. 58.7%) (all P < 0.001) than symptomatic group. More asymptomatic patients were underdiagnosed (91.9% vs. 54.3%, P < 0.001) than symptomatic patients.</p><p><b>CONCLUSIONS</b>This large population-based survey confirmed a high prevalence of asymptomatic COPD patients in China. More use of spirometry screening test may be important to the early detection of COPD.</p>

A study on the methodology regarding the prevalence survey of chronic obstructive pulmonary disease in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the methodology on prevalence study of chronic obstructive pulmonary disease (COPD) in line with the world, to obtain accurate epidemic data of COPD in China.</p><p><b>METHODS</b>A national multi-center cross-sectional survey on prevalence, risk factors and burden of COPD was conducted in China. In each area, a population-based cluster sample of approximately 1450 individuals aged 40 years or older was interviewed, using standardized questionnaires that were revised on the methodology of burden of lung diseases (BOLD) study and according under the context of China. All participants were submitted to pre-bronchodilator spirometry. Those with airflow limitation received post-bronchodilator spirometry, physical examination, X-rays of chest and EKG (electrocardiogram) tests. The post-bronchodialators FEV1/FVC < 70% was identified as having COPD.</p><p><b>RESULTS</b>Investigation has been completed with the same standardized procedures by all sites, up to the requirement of quality control. Over 85.0% of the spirometry tests and 95.0% of questionnaires had met the criteria of quality control in each area. Overall, 95.2% of the data was valid with acceptable spirometry and questionaire, and the valid response rate was 79.0%.</p><p><b>CONCLUSION</b>The protocol was in line with the international standards, by which the prevalence of COPD in China was of adequate quality and valid.</p>

Study on the prevalence rate of chronic obstructive pulmonary disease in northern part of Guangdong province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence of chronic obstructive pulmonary disease (COPD) and its risk factors in population over 40 years old in northern part of Guangdong province.</p><p><b>METHODS</b>Using uniform scheme, procedures and questionnaire, a cluster-randomized-sampling survey for the population aged over 40 years in a rural area of Shaoguan in the northern part of Guangdong province was performed. Spirometry was performed for every participant, followed by a bronchodilatation test when bronchial obstruction was present.</p><p><b>RESULTS</b>There were 1468 cases with complete data from 1498 people aged >or= 40 years including 640 males, 828 females with an average age of 54.3 years old. The total prevalence of COPD was 12.0%. The prevalence of COPD in males was significantly higher than that in females (18.3% vs. 7.1%, P < 0.01). Only 80.7% of the patients with COPD presented one or more symptoms as cough, phlegm, or dyspnoea. Underdiagnosis of COPD would be quite serious. Only 26.1% of the cases was previously diagnosed to have chronic bronchitis, emphysema, or COPD. Smoking was an important risk factor to COPD and 78.4% of the patients with COPD were smokers. However, relation of biomass and COPD called for further investigation.</p><p><b>CONCLUSION</b>Prevalence of COPD was much higher than expected in the northern part of Guangdong while smoking was an most important risk factor of COPD. Lung function test seemed to be of great importance to COPD diagnosis, especially in the earlier period of COPD.</p>