A. J. Oosting

Clinical evaluation of the effect of anti-allergic mattress covers in patients with moderate to severe asthma and house dust mite allergy: a randomised double blind placebo controlled study

Background: The use of anti-allergic mattress covers in patients with asthma can result in a large reduction in the level of house dust mite allergen in dust samples. Apart from a reduction in histamine induced bronchial hyperresponsiveness, there are few data on the effect of mattress covers on clinical efficacy and quality of life in patients with moderate to severe asthma. Methods: Thirty patients with asthma and house dust mite allergy were studied in a randomised, double blind, placebo controlled study. Before and after using anti-allergic covers for 1 year, dust was collected from the mattresses to determine concentrations of Dermatophagoides pteronyssinus (Der p 1), and bronchial hyperresponsiveness and quality of life were measured. The patients scored their symptoms (lungs and nose), morning and evening peak flow values, and rescue medication for 14 days before and after the intervention period. Results: There was a significant reduction in the concentration of Der p 1 in the dust collected from the mattresses in the actively treated group after 1 year compared with before treatment; no change was found in the placebo group. In both the actively treated and placebo groups there was no significant improvement in PC20 histamine. Quality of life improved similarly in both groups. The symptom score of the lower airways did not significantly change in either group. A significant decrease in nasal symptom score was seen in the actively treated group compared with before treatment, but there was no significant difference between the groups. No changes in morning and evening peak flow values, peak flow variability, nor in the use of rescue medication were found in either group. Conclusion: The use of anti-allergic mattress covers results in significant reductions in Der p 1 concentrations in carpet-free bedrooms. However, in patients with moderate to severe asthma, airways hyperresponsiveness and clinical parameters are not affected by this effective allergen avoidance.

Prevalence and severity of allergic rhinitis in house dust mite-allergic patients with bronchial asthma or atopic dermatitis

Background Allergic rhinitis, asthma and atopic dermatitis are closely associated. Although population‐based studies report a high prevalence of rhinitis among asthma patients, less is known of the association between rhinitis and atopic dermatitis and the severity of concomitant rhinitis.

The effect of encasings on quality of life in adult house dust mite allergic patients with rhinitis, asthma and/or atopic dermatitis

Background:  Environmental control has been put forward as an integral part of the management of house dust mite (HDM) allergy in sensitized patients. To validate this statement allergic disorders involved in HDM allergy – allergic asthma, rhinitis and atopic eczema/dermatitis syndrome (AEDS) – should be taken together and studied in terms of the efficacy of environmental control. Because a generic quality of life questionnaire exceeds the border of disease, this may be used as major outcome parameter.

The effect of anti-allergic mattress encasings on house dust mite-induced early- and late-airway reactions in asthmatic patients. A double-blind, placebo-controlled study

Background Anti‐allergic mattress encasing may provide clinical benefit in asthmatic patients. However, the effect of mattress encasings on allergen‐specific parameters, such as bronchial reactions to house dust mite (HDM) challenge, is not clear.

The unfavorable effects of concomitant asthma and sleeplessness due to the atopic eczema/dermatitis syndrome (AEDS) on quality of life in subjects allergic to house‐dust mites

Background: Allergic rhinitis, asthma or the atopic eczema/dermatitis syndrome (AEDS) may independently impair quality of life in patients. However, although many allergic patients may suffer from more than one disorder, the effect of concomitant disease — in particular, the impact of AEDS — is largely unknown. As part of a large multicenter clinical trial on the efficacy of mattress casings in house‐dust mite (HDM) allergy, generic quality of life in a mixed population of 224 subjects with rhinitis (n = 198) and/or asthma (n = 111) and/or AEDS (n = 64) was studied. The study aimed to estimate quality of life impairment in these atopic patients and to address the questionissue of whether one atopic disorder goes beyond other existing allergic diseases, thereby causing further impairment to quality of life.

Comparison of a generic and a rhinitis-specific quality-of-life (QOL) instrument in patients with house dust mite allergy: relationship between the SF-36 and Rhinitis QOL Questionnaire

Background Generic and disease‐specific quality‐of‐life (QOL) questionnaires are commonly used in subjects with allergic rhinitis (AR). AR, however, is closely associated with other disorders such as bronchial asthma and atopic dermatitis (AD). These co‐morbid associations may have an effect on the inter‐relation of generic and disease‐specific QOL outcomes and the behaviour of this inter‐relation in time.

Differential effect of mattress covers on the level of Der p 1 and Der f 1 in dust

Background Exposure to house dust mite (HDM) allergens can lead to the development of allergic complaints. Mattress covers seem to be an obvious option for lowering allergen exposure in sensitized individuals. Previous studies have shown that Dermatophagoides pteronissinus was the most prevalent HDM species in the Netherlands.

Anti‐allergic mattress covers in asthma: to do or not to do?

Although early studies on mite-impermeable mattress covers suggested clinical benefit in asthma [1, 2], other double-blind placebo-controlled studies show less favourable results [3, 4]. The results of the study by Luczynska et al. [5] published in this issue of the journal lack evidence of clinical benefit in mild-to-moderate asthmatic patients, despite a decrease in allergen load. These findings seem to be in contrast to the fact that house dust mite (HDM) allergen has proved to be an important trigger in allergic asthma. From a number of cross-sectional and longitudinal studies, it can be concluded that there is a very close association between HDM exposure and HDM sensitization [6]. In addition, HDM exposure in already sensitized individuals can trigger an exacerbation of asthma, and prolonged exposure can lead to the persistence of symptoms [7]. Asthma is usually more severe in sensitized patients who are exposed to higher allergen levels [8]. There is clear biological plausibility for the role of HDM allergens, in that the proteolytic activity of their enzymes can actively damage the airway epithelium. In effectively mite allergen-free environments, as in hospitals [9] or in highaltitude Alpine clinics [10], the condition of asthmatic patients improves both symptomatically and in terms of non-specific bronchial responsiveness. Even 1 month at high altitude can result in a reduction in airways inflammation, measured as adenosine 50-monophosphate (AMP), bronchial hyper-responsiveness (BH), blood eosinophils and eosinophilic cationic protein (ECP) [11]. Ten weeks of high-altitude allergen avoidance in adolescent patients with persistent asthma, despite treatment with high-dose inhaled corticosteroids, resulted in improvement of asthma, assessed by clinical and inflammatory markers of disease severity. These findings indicate that short-term rigorous allergen avoidance can improve the control of severe asthma over and above what can be achieved by high doses of inhaled steroids [12]. Although it is impossible to achieve such low levels of HDM exposition at sea level as at high altitude, in the past much effort has been put in attempts to reduce HDM exposition in the home environment. Methods such as extensively vacuum cleaning, use of acaricides, air filters, ventilation, smooth floors, removing carpets and curtains, etc. have been used in order to reduce HDM exposition. Reduction of allergen exposure in the bedroom and the bed is considered to be the primary target of avoidance measures, since the bed is the most important habitat and source of mite allergens to which we are exposed for many hours during sleep. The most effective avoidance measure is to cover the mattress, pillows and duvets with mite allergen-impermeable covers [1–3] and washing all bedding in hot temperature [13]. Covering the mattresses, pillows and duvets is a relatively simple method that can substantially reduce night-time HDM exposure. Its efficacy can be studied in a placebo-controlled manner. Therefore, over the past few years many studies have focused on this subject.