Relationship between asymptomatic bronchial hyperresponsiveness and asthma:Three year follow up in a survey for bronchial responsiveness
Objective To study factors affecting the development of asymptomatic bronchial hyperresponsiveness to symptomatic asthma. Method 41 cases with asymptomatic bronchial hyperresponsiveness detected in a survey in 1997 and 31 cases with normal bronchial responsiveness were followed. Results 18%(7/38) of the asymptomatic bronchial hyperresponsiveness developed asthma. This rate was higher than that of the control (0%, 0/30) and with statistical significance ( P 0.05). Among the 38 cases of asymptomatic bronchial hyperresponsiveness that were followed up, the incidence rate with family history of asthma was 54.5%(6/11), higher than that of without family history (3%,1/27) and with statistical significance( P 0.01).The His PD20 FEV1 and sIgE Q value of the symptomatic cases 1.4±0.72μmol and 2.81±13.25 were different from those of asymptomatic cases 5.63±2.58μmol and 12.1±11.53 respectively, with statistical significance ( P 0.05 and P 0.05 ). Conclusion Some asymptomatic bronchial hyperresponsiveness would develop asthma within certain period of time, especially those with family history.Cases of asymptomatic bronchial hyperresponsiveness with high sIgE Q value, ECP positive, and His PD20 FEV1≤1.96μmol could easily develop symptomatic asthma. These individuals should be given preventing treatment.