Objective: To evaluate the effect of airway responsiveness on asthma and to study the causes of asthma.
Methods: The 641 nuclear families were confirmed by indicator cases with asthma in three counties. Investigation and methacholine challenge test were conducted for all relatives of the nuclear families. The data were by EPI5.01 and the odds ratio (OR) was employed to evaluate the correlation between asthma and airway responsiveness.
Results: 72 percent of persons with asthma history showed airway hyperresponsiveness, but only 70 per cent of persons with airway hyperresponsiveness suffered asthma. The risk for asthma in relatives with positive airway responsiveness was 5.8 times higher than those with negative airway responsiveness (P > 0.01) among the nuclear families.
Conclusion: Airway hyperresponsiveness is one of the risk factors of asthma.