[A cross-sectional survey of familial aggregation of chronic obstructive pulmonary disease: in seven provinces/cities in China].

OBJECTIVE: To investigate the familial aggregation in chronic obstructive pulmonary disease (COPD).

METHODS: Based on a cross-sectional survey in seven provinces/cities in China (Beijing, Shanghai, Guangdong, Liaoning, Tianjin, Chongqing and Shaanxi) from 2002 to 2004, the familial aggregation of COPD was investigated with multi-stage cluster random sampling method.One urban and one rural area were selected as samples from each of seven provinces/cities. All residents equal or older than 40 years old received questionnaires and pulmonary function tests. Questionnaires included risk factors of COPD, respiratory symptoms, quality of life, diagnosis and prevention conditions of COPD. Bronchodilator tests, physical examination, X-ray and electrocardiograph (ECG) were conducted in those subjects.In pulmonary function tests, the ratio of the first second forced expiratory volume (FEV1) /forced vital capacity (FVC) less than 70% fulfill the diagnostic criteria of COPD.If any of siblings and parents had chronic bronchitis, emphysema, asthma or COPD, it should be considered as a positive family history of COPD-related disease.Otherwise, it was negative.

RESULTS: FEV1 was lower in the subjects with a family history of COPD-related diseases than in those without [(2.24 ± 0.70) L vs (2.28 ± 0.73) L]. The prevalence of COPD in the population with history of COPD-related diseases was 12.1% (540/4 481), which was significantly higher than that without [7.2% (1 128/15 764), χ(2) = 110.599, P < 0.001]. After adjusted for potential confounder, the population with a family history of COPD-related diseases still had much higher incidence of COPD [OR = 2.18 (95%CI 1.94-2.46)]. Furthermore, the population having two or more first-degree relatives with COPD-related diseases, exhibited the highest likelihood of COPD [OR = 2.48 (95%CI 2.00-3.08)]. The population having only one first-degree relative with COPD-related diseases showed an increased risk of COPD with an OR = 2.10 (95%CI 1.84-2.40) compared with those without any one. Those whose father, mother or siblings had COPD-related diseases were similarly likely to have COPD, with an OR of 1.54 (95%CI 1.32-1.80), 1.83 (95%CI 1.56-2.15) and 1.81 (95%CI 1.48-2.23), respectively.

CONCLUSIONS: There is a familial aggregation in COPD. The more relatives have COPD-related diseases in the family, the greater risk of COPD the subject will have.