RESUMEN
BACKGROUND: Inhalation of house dust mite (HDM) allergen may provoke attacks of asthma. OBJECTIVE: We investigated whether a double-blind placebo-controlled community-based study aimed at reducing the HDM allergens in the bedrooms of HDM sensitive asthmatic children using the best methods available would prove beneficial to the children's health. METHODS: The children (mean age 9.9 years, 34 boys) were recruited by a questionnaire submitted to 7386 families in a geographically-defined area of the UK. Subjects were chosen to take part in the double-blind placebo-controlled trial if they were asthmatic, skin sensitive to mites, and had mite allergen in their mattresses. Seventy children were randomly allocated to groups. In the active group, the children's bedrooms were treated with an acaricide (Acarosan) and the mattresses, pillows and duvets were encased in exclusion covers. The control group received placebo treatments. RESULTS: Forty-nine complete data sets were obtained. Applying bedding covers and Acarosan led to a median reduction of 480 ng (100%) in mite allergen on the mattress vs 215 ng (53%) reduction in placebo-treated group by 6 weeks. No evidence was found that the acaricide reduced mite allergen level. A change in bronchial reactivity to histamine was observed in the children after 6 weeks. This was not associated with any change in thrice-daily records of peak expiratory flow rate. By 24 weeks, the actively-treated children had improved forced expiratory volume in 1s (FEV1) and fewer required bronchodilator therapy or reported asthmatic symptoms than did the controls. CONCLUSIONS: The results suggest that mite removal procedures may modestly improve mite-sensitive asthmatics and could perhaps be of value in exceptionally mite-sensitive and/or highly mite-exposed individuals whose response to the attempted removal should be measured.
Asunto(s)
Asma/inmunología , Asma/prevención & control , Control de Ácaros y Garrapatas , Alérgenos/efectos adversos , Ropa de Cama y Ropa Blanca/efectos adversos , Hiperreactividad Bronquial/inmunología , Hiperreactividad Bronquial/prevención & control , Pruebas de Provocación Bronquial , Niño , Método Doble Ciego , Polvo/prevención & control , Histamina/inmunología , Humanos , Masculino , Pruebas de Función RespiratoriaRESUMEN
BACKGROUND: Asthma is a common chronic disease of childhood. House dust mite (HDM) are known to be a major source of allergen affecting atopic asthmatics. No single control method has been demonstrated to consistently reduce asthma. OBJECTIVE: We investigated the effect of a combination of two methods of HDM allergen control on HDM allergen content in the bedding and carpets of asthmatic children. METHODS: This was a double-blind placebo-controlled trial treating the bedrooms of 56 mite-sensitive asthmatic children. The carpet and the mattress, duvet and pillows (bedding) in the bedroom of children of the active group were treated with the acaricide Acarosan (benzyl benzoate). The bedding was then encased in vapour permeable waterproof fabric (Intervent--cotton coated with polyurethane) for 24 weeks. The carpet and bedding of the control group were treated with placebo and the bedding encased in cotton covers for 24 weeks. Dust samples were collected from all these items in a standard manner at regular intervals and Der p I content analysed. RESULTS: The group with active treatment had a median reduction of 480 ng (100%) in mite allergen from the mattress vs 215 ng (53%) reduction in placebo-treated group by 6 weeks. The Der p I content of the active group's bedding was always less than the placebo group after treatment (P < 0.01). The acaricide applied to the carpets or inside the mattress covers was ineffective in reducing allergen content. CONCLUSION: This study confirms the effectiveness of encasing covers in reducing the mite allergen exposure but indicates there is no further advantage in applying acaricide simultaneously.