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COPD in China: A tale of two people

SUN Yong-chang

The term chronic obstructive pulmonary disease (COPD) has been well known and the disease extensively studied for more than a decade in China, but only recently has great progress been made in the epidemiology and management of this highly prevalent disease in this country. Historically, beginning in the early 1960s, long before the definition of COPD was widely accepted, a great number of studies that included traditional Chinese medicine had been performed on chronic bronchitis, emphysema, and related respiratory failure and cor pulmonale.

Cough and sputum production can be present for many years before the development of airflow limitation and are often ignored by patients and attributed to aging or lack of conditioning. As airflow limitation worsens in stage II, moderate COPD, patients often experience dyspnea, which may interfere with their daily activities. Typically, this is the stage at which they seek medical attention and may be diagnosed with COPD. However, some patients do not experience cough, sputum production, or dyspnea in stage I, mild COPD, or in stage II, moderate COPD, and do not seek medical attention until their airflow limitation becomes more severe or their lung function is acutely worsened by a respiratory tract infection. These cases of asymptomatic COPD were most likely to be underdiagnosed. In this issue of the journal, Lu et al  report the prevalence and characteristics of asymptomatic COPD from a large population-based survey of the prevalence of COPD in China. The results show that, among the 1668 patients who were diagnosed with COPD from the 25,627 sampled subjects, 589 (35.3%) were asymptomatic. As can be expected, asymptomatic patients had significantly higher forced expiratory volume in 1 second (FEV1) than their symptomatic counterparts. More patients with asymptomatic COPD were underdiagnosed (91.9% vs. 54.3%, P <0.001) as compared to those with symptomatic disease. From a local survey of 1624 rural residents reported earlier, Yao et al found that among 148 cases of spirometry-confirmed COPD, 42% (62/148) were asymptomatic.

In rural areas among village residents, the prevalence of COPD was thought to be higher while the diagnosis is inadequate and the management poorer compared to big cities in China. Epidemiological studies confirmed this disparity. In a large population-based survey of COPD reported by Zhong et al, the overall COPD prevalence was significantly higher in rural areas (8.8%) compared to urban areas (7.8%) (P=0.007). Of the six sites where the prevalence of COPD was compared between urban and rural areas, four reported a higher prevalence of COPD in the rural areas. Liu et al compared the prevalence of and associated factors for COPD in populations over 40 years old in an urban (Liwang) and a rural (Yunyan) area in Guangdong. The results showed that the overall prevalence of COPD in rural Yunyan was significantly higher than that in urban Liwang (12.0% vs. 7.4%), and that in a subpopulation of non-smoking women the prevalence of COPD was also higher in Yunyan than in Liwang (7.2% vs. 2.5%). The use of biomass fuel was higher in rural Yunyan than in urban Liwang (88.1% vs. 0.7%). Univariate analysis showed a significant association between COPD and exposure to biomass fuel for cooking. Multivariate analysis showed a positive association between COPD and urban/rural area (surrogate for fuel type and local exhaust ventilation in kitchen) after adjustment for sex, age group, body mass index, education, occupational exposure, respiratory disease in family, smoking status, quality of life and cough in childhood.

A similarly-designed survey carried out in a large northern city also showed similar result. The study investigated the prevalence of COPD in a sample of 1500 residents from five city communities and 1508 residents from four natural villages in the Tianjin administrative region. The prevalence of COPD was 8.3% in the city people as compared to 11.4% in the rural people. This study also revealed that, while 19.8% (25/126) of the city patients received regular treatment for the disease, only 2.6% (2/78) of the rural patients did.

Patients in the rural areas also have less understanding of the disease, and fewer are able to seek medical attention. In the five villages of Yanqing county under the jurisdiction of Beijing, among the 148 patients with COPD confirmed by spirometry in the above-mentioned epidemiological study, none had ever heard the term COPD, and none had been diagnosed with the disease. Lung function tests and health education had never been performed for these patients. Only 4.1% (6/148) of the patients in stable stage had taken theophylline irregularly. None of the stable COPD patients had taken inhalers regularly or temporally. During acute exacerbation, only 6.8% (10/148) took theophylline and 6.8% (10/148) had antibiotics. Only 3.4% (5/148) of the patients had been admitted to a hospital during the past year. In a subpopulation analysis of the data from the national survey mentioned above, Zhou et al found that in COPD patients living in rural areas, only 30.0% (249/830) had ever been diagnosed with COPD, bronchitis, emphysema, or asthma. Only 2.4% (20/830) had ever received a spirometry test, and only 7.9% (50/634) of the patients in GOLD stage II or over had received regular drug treatment.

It is regrettable to note that simple spirometry, the gold standard for COPD, is almost completely unavailable to patients in the rural areas. As compared to the overall low percentage (6.5%) of patients who had received a spirometry test in the national survey reported by Zhong et al, even in subjects with GOLD stages III and IV disease, the percentage was only 9.2%–9.9%.

Standard diagnosis and management of COPD has been implemented in big city hospitals, and even in community clinics, while urban people are beginning to become aware of the disease owning to educational programs. Respiratory physicians and personnel in large hospitals are collaborating with community doctors to improve understanding of COPD and therefore the comprehensive management of the disease, by providing educational programs and spirometry tests. However, in rural areas, simple spirometry is lacking even in county hospitals, the local medical centers covering populations varying from hundreds of thousands to more than one million. For rural patients, visiting a doctor is largely driven by symptoms. However, cough and sputum production are mostly regarded as a nuisance rather than signs of a potentially debilitating disease. To make things worse, the medical coverage for rural residents is inadequate; most of the patients have to pay a major part of their medical expense. They are reluctant to seek medical attention in larger hospitals, and if the symptoms become worse, they return to the village clinic for symptomatic relief using antitussives, mucolytics, oral short-acting bronchodilators or antibiotics. When they finally have to go to large hospitals, the disease has progressed to late stages, often with respiratory failure and cor pulmonale. For example, in the local survey in Yanqing county of Beijing, 18.24% (27/148) of the patients with COPD were diagnosed with cor pulmonale according to the criteria of ECG and chest X-ray.

The disease burden of COPD is heavy. He et al investigated the medical expenses in the last 12 months for COPD patients (n=723) in six cities in China. The average direct medical cost (including medicine, outpatient and inpatient costs) was 11,744 RMB Yuan annually. A survey of the cost of hospitalization for patients with acute exacerbation of COPD from four hospitals in Beijing city showed an average cost of 11,597.6 RMB Yuan for one hospitalization. The costs increased in patients with non-invasive ventilation, invasive mechanical ventilation, ICU stay, antibiotics, systemic glucocorticoids, and poor prognosis.

Considering the enormous economic burden of COPD, early diagnosis and comprehensive management to slow disease progression or to prevent exacerbations are of great importance, especially for the low-income rural patients. To achieve this goal, simple spirometry should be available in local hospitals for rural residents, and ideally performed in physical check-ups for high-risk individuals, for example, heavy smokers. This approach is particularly important for the diagnosis of asymptomatic COPD. The recommended medical therapies, including long-acting anticholinergics, inhaled long-acting β2 agonists or its combination with glucocorticoids, are unaffordable to most patients in rural areas. Therefore, drugs that are cheap, safe and effective in relieving symptoms and ideally reducing exacerbations are urgently needed. The PEACE study, which demonstrated the effectiveness of carbocisteine in reducing the rate of exacerbations of COPD, and another study showing that long-term use of low-dose theophylline was able to improve symptoms and reduce the rate of exacerbations, are of greater benefit to these patients. With rapid modernization in China, more rural areas are becoming urbanized, but still more than 60% of the whole population is living in rural villages. Medical practice requires a translation of disease-specific recommendations to the circumstances of individual patients, the local communities in which they live and the health systems from which they receive medical care. We expect to see the best practices implemented, and hence an improved prognosis for COPD patients in rural areas, at least comparable to their urban fellowmen.

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Chin Med J 2010;123 (12):1491-1493

(Correspondence to: SUN Yong-chang, Department of Respiratory Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China)