Abstract
Background Bronchial hyperresponsiveness (BHR) is a keypathophysiological feature of asthma. Even thoughthere is no diagnostic test for asthma, bronchial provocationtests, such as the methacholine test, are useful in the diagnostic procedure for confirming a diagnosis of asthma.
Aim To estimate prevalence and determinants of BHR in northern Vietnam.
Methods The study was conducted in urban and rural Hanoi. 5872 randomly selected subjects(83% of invited) aged 21 -70 years participated in a questionnaire survey in 2007-2008. Of them, 1500 subjects, 750 from each of the two areas, were randomly selected for clinical examinations including astructured interview, lung function test, methacholine test and skin prick test (SPT). In total, 684 subjects (46%) participated, and methacholine test was performed in 366 subjects following a method developed in Sweden. The cut-off lines used in the analyses were PC20 ≤1mg/ml, ≤2mg/ml and≤8mg/ml.
Results The prevalence of BHR defined by the three cut-off lines were 6.3% at doses ≤1mg/ml, 9.6% at doses ≤2mg/ml, and 16.4% at doses ≤8mg/ml. Among those who had PC20 ≤2mg/ml, only 11.4% reported physician-diagnosed asthma vs. 3.6% (p=0.029) among those who did not react at that dose, while 26% of those with PC20 ≤2mg/ml reported wheezing with breathlessness vs. 11% (p=0.014) among those who did not react. Corresponding figures for use of asthma medicines were 5.7% vs. 0.6% (p=0.005). A majority of those with PC20 ≤2mg/ml reported at least one symptom common in asthma.
Conclusions As asthma prevalence among adults in Vietnam has been estimated at 2-5%, the results of our study indicate that asthma is underdiagnosed in Vietnam.
- © 2014 ERS