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[The relationship between bronchial hyperresponsiveness and chronic obstructive pulmonary disease]
1Cardiovascular Institute & Fuwai Cardiovascular Hospital, CAMS & PUMC, Beijing 100037, China.
Objective:
To explore the relationship between bronchial hyperresponsiveness and chronic obstructive pulmonary disease (COPD).
Methods:
154 smokers with COPD (FEV1/FVC < 70%) served as a study group and 154 smokers without COPD as a control group and 23 never-smokers as a healthy control group from 23 villages in Fangshan Distract, Beijing in June, 1996. The patients with self-reported and doctor-diagnosed asthma were excluded from participants. Those subjects were divided into a positive group and a negative group based on methacholine bronchial responsiveness. All subjects were worked up in May, 2000.
Results:
(1) Baseline case-control study: The positive rate of bronchial hyperresponsiveness was 78% in the study group, PC20 = (1.4 +/- 1.6) g/L; however 28% of the matched group were positive, PC20 = (2.7 +/- 2.3) g/L, (P < 0.001); (2) Prospective study: Of 154 pairs case-controls 241 subjects were followed up in May 2000. The rate of following up was 78.2%. The incidence of COPD was 23.7% in 38 subjects without COPD with positive hyperresponsiveness, however incidence of COPD was 9.5% in 84 subjects without COPD with negative hyperresponsiveness (P = 0.036), the relative risk (RR) = 2.5. The rate of FEV1/FVC > or = 70% was 12.9% in 93 patients with COPD and positive hyperresponsiveness, however it was 30.8% in 26 patients with COPD and negative hyperresponsiveness (P = 0.031).
Conclusion:
In smoking population, the bronchial hyperresponsiveness lead to more chronic obstructive pulmonary disease and it may be one of the susceptible risk factors for COPD.