Prevalence of bronchial hyperresponsiveness to 4.5% saline and its relation to asthma and allergy symptoms in Austrian children

Abstract

The prevalence of asthma in school children has been reported to have increased, with wide variations between countries. To allow comparison of prevalence data, objective markers of asthma should be measured. Therefore, we assessed the prevalence of bronchial hyperresponsiveness (BHR) to hypertonic saline and its relation to asthma and allergy symptoms in 507 Austrian school children, aged 12-15 yrs in a cross-sectional, community based survey. These children were selected from 3,371 children who had answered a self-administered written questionnaire on asthma, hay fever, eczema and environmental factors. The prevalence of BHR to hypertonic saline was 14% and the majority (70%) of the children had mild BHR. The prevalence of wheeze in the last 12 months was 12% and of a diagnostic label of asthma was 6%. Fifty three per cent of the children with symptoms in the last 12 months and a diagnostic label of asthma had BHR, and 33% of those with symptoms in the last 12 months regardless of a diagnostic label of asthma showed a positive response to hypertonic saline. Atopic dermatitis, a diagnostic label of asthma, night cough apart from colds, wheeze in the past 12 months (but not "former wheeze") and male gender were significantly associated with increased response to 4.5% saline in the final logistic regression model. These results show that the prevalence of asthma symptoms in the last 12 months and the prevalence of bronchial hyperresponsiveness to hypertonic saline are twice that of a diagnosis of asthma and that asthma might be underdiagnosed in the present population. The response to hypertonic saline is most strongly associated with current asthma and allergy symptoms. A combination of a "diagnostic label of asthma" and "asthma symptoms in the last 12 months" might best reflect "current asthma" in epidemiological studies in this population.

Lack of a late asthmatic response after hypertonic saline challenge in children

“…Twenty-five out of 75 children that had responded positively to a bronchial provocation test using 4.5% saline in an epidemiological study, which had been carried out 1 yr previously in Salzburg, Austria [3] agreed to be rechallenged and fulfilled the following inclusion criteria for taking part in the present study: a previous positive response to hypertonic saline challenge; an assessment of respiratory disease status by a paediatric respiratory physician; stable asthma with inhaled b 2 -agonists on demand to control symptoms; baseline forced expiratory volume in one second (FEV1) >65% of predicted value; no inhaled corticosteroids or cromolyn during the last 2 months; no chest infection in the preceding 4 weeks; and the ability to perform reproducible pulmonary function tests.…”

Respostas fisiológicas em adolescentes obesos submetidos à broncoprovocação com solução salina hipertônica

“…A estatura foi aferida utilizando-se um estadiômetro, com resolução de 0,1 cm; para efetuar a medida, o avaliado deveria estar descalço, em apneia inspiratória e com a cabeça posicionada no plano de Frankfort (14). Por intermédio das medidas de MC e estatura, aérea é aumentada em indivíduos asmáticos e obesos (9,10,11,12). Além disso, a literatura relata que os estudos conduzidos nesse âmbito demonstram uma maior prevalência de asma em indivíduos obesos em comparação com asmáticos não obesos (4,12).…”

“…Com dificuldade de obtenção dos métodos diretos, os testes de broncoprovocação por exercício físico e solução salina hipertônica têm sido utilizados para avaliar a hiper-responsividade com maior frequência (4,10,11,12). Apesar de serem métodos análogos, o teste de exercício demonstra uma perda hídrica das vias aéreas para o meio exterior decorrente da hiperapneia fisiológica.…”

“…A inalação de solução salina hipertônica reproduz este mecanismo, com as vantagens de ser realizada com volume corrente e não necessitar de colaboração do paciente em atingir a carga máxima de esforço (9,10). Embora a prova de broncoprovocação por solução salina hipertônica tenha sido aplicada em investigações para avaliar a hiper-responsividade, as evidências desse efeito na relação entre obesidade e sintomas respiratórios na população pediátrica são limitadas (10)(11)(12). Nesse sentido, o presente estudo visou avaliar as respostas fisiológicas em adolescentes obesos submetidos a brocoprovocação por inalação de solução salina hipertônica.…”

Protective effect of bronchial challenge with hypertonic saline on nocturnal asthma

“…Over the past 20 years, bronchial challenges with HS have been increasingly used as a relevant test for the diagnosis, assessment of severity and evaluation of treatment of asthma (3). The HS challenge has been shown to be simple, safe and reproducible (4).…”