[Epidemiologic analysis of COPD in Guangdong province].

Objective: To survey the prevalence of chronic obstructive pulmonary disease (COPD) in urban and rural areas in Guangdong Province and relevant risk factors.

Methods: Using the same protocol including Burden of Obstructive Lung Disease (BOLD) questionnaire, a questionnaire survey was conducted among 3449 respondents, 1370 males and 1916 females, aged over 40 with an average age of 56.8, by random disproportional cluster sampling in Liwang District of Guangzhou City and Yunyan Town, Lechang City, northern Guangdong Province. Spirometry was performed in all subjects. Lung function indices were regarded as gold criteria of diagnosis of COPD.

Results: There were 3286 cases with full data and good quality spirometry test, 1370 males and 1916 females, aged 56.8. The total prevalence of COPD was 9.4%. The prevalence of COPD in the males was 15.9%, significantly higher than that in the females (4.8%, P < 0.01). The prevalence in the rural area was 12.0%, significantly higher than that in the urban area (7.4%, chi(2) = 20.3, P < 0.01). 67.7% of the patients with COPD presented symptoms such as cough, expectoration and/or dyspnoea. 58.7% of the COPD patients (78.9% of the male patients and 10.9% of the female patients) smoked. The odd ratio (OR) for COPD in the smokers was 2.59 (95% CI 1.87 - 3.59). Only 15.1% of the smokers (17.9% of the male smokers and 4.1% of the female smokers) developed COPD. No significant relationship was found between pack years of cigarette smoking and COPD prevalence. The risk of COPD was increased when biomass fuels were used in house cooking (OR = 1.54 95% CI 1.08 - 2.20). Furthermore, the combination of biomass fuels and cigarette smoking further increased the risk with the OR of 4.41 (95% CI 3.22 - 6.04), indicating a synergetic impact of smoking and biomass burning on the prevalence of COPD. The Prevalence of doctor-diagnosed COPD based on the clinical manifestation was significant lower than the actual prevalence (only 31.0%).

Conclusions: COPD is a very common disease in Guangdong. The prevalence of COPD is higher in the rural area than in the urban area, which may be attributed to the synergic effect of smoking and biomass burning. Lung function test is of great importance in COPD diagnosis, especially in the earlier stage of COPD and those asymptomatic COPD patients.