Is allergen avoidance effective?

Effective allergen avoidance for reducing exposure to house dust mite allergens and improving disease management in adult atopic asthmatics

OBJECTIVE

We investigated the best strategy for adult asthmatics to avoid exposure to Dermatophagoides group (Der-1) allergens.

METHODS

Adult atopic asthmatics (n = 111) followed a 32-item checklist for avoiding Der-1 allergen exposure. Twenty-five patients were excluded through incomplete sampling; 50 remaining patients encased their pillows/futons/mattresses in microfine-fiber covers, 13 used vacuum cleaners with dust-mite-collection nozzles, and 23 acted as non-intervention controls. During August-October 2010 and August-October 2011, dust samples were collected in Petri dishes placed in bedrooms for 2 weeks and from mattresses/futons by using adhesive tape on one morning. A Der-1 level decrease was defined as a mean 2011 Der-1 level of <1 as a ratio of the 2010 level on tape or Petri dish samples. We analyzed the associations between Der-1 level change (by ELISA) and % weekly variability in peak expiratory flow (PEF) or fraction of exhaled nitric oxide (FeNO) after intervention.

RESULTS

Der-1 levels decreased significantly in the covers group but not the vacuuming group. FeNO levels and PEF variability were unchanged in both groups. In patients whose Petri dish or tape samples showed decreased Der-1 levels, the % PEF variability was lower in 2011 than in 2010, but FeNO levels were unchanged. Three interventions (vacuuming all family members' mattress/futon surfaces at least weekly or after exposure of the futons to sunlight, and floor wiping before vacuuming), plus using covers, were the most effective management strategy in reducing Der-1 levels.

CONCLUSIONS

This environmental and bedding maintenance program may help manage adult atopic asthma.

Encasing bedding in covers made of microfine fibers reduces exposure to house mite allergens and improves disease management in adult atopic asthmatics

BACKGROUND

Studies of avoidance of exposure to group 1 allergens of the Dermatophagoides group (Der p 1) have not yielded consistent improvements in adult asthma through avoidance. We explored whether the use of pillow and bed covers and allergen-avoidance counseling resulted in Der 1-level reduction, as measured by enzyme-linked immunosorbent assay, and thus improved asthma symptoms in adult patients.

METHODS

Twenty-five adult patients with moderate or severe atopic asthma were randomized into intervention and control groups. Intervention patients slept on pillows and mattresses or futons encased in microfine-fiber covers and were counseled in allergen avoidance through bedroom cleaning. Control patients received neither special covers nor counseling. In the period August to October in 2009 (pre-intervention) and 2010 (post-intervention), dust samples were collected in open Petri dishes placed in bedrooms for 2 weeks and by rapid lifting of dust from bedding and skin using adhesive tape on the morning of 1 day of Petri dish placement. We examined the associations between changes in Der 1 level (as measured by enzyme-linked immunosorbent assay) and clinical symptom score, minimum % peak expiratory flow, and fraction of exhaled nitric oxide.

RESULTS

Der 1 allergen levels on the mattress/futon covers and near the floor of the bedrooms of intervention patients, but not controls, were lower in 2010 than in 2009. From 2009 to 2010, asthma symptom scores decreased significantly, and minimum % peak expiratory flow increased significantly, in intervention patients. The fall in Der p 1 concentration was correlated with a reduction in the fraction of exhaled nitric oxide.

CONCLUSIONS

Minimization of Der 1 allergen exposure by encasing pillows and mattresses or futons and receiving counseling on avoiding exposure to indoor allergens improved asthma control in adult patients.

Major mite allergen Der f 1 concentration is reduced in buildings with improved energy performance

BACKGROUND

Environmental conditions play a crucial role in mite growth, and optimal environmental control is key in the prevention of airway inflammation in chronic allergic rhinoconjunctivitis or asthma.

OBJECTIVE

To evaluate the relationship between building energy performance and indoor mite allergen concentration in a cross-sectional study.

METHODS

Major allergen concentration (Der f 1, Der p 1, mite group 2, Fel d 1 and Bla g 2) was determined by quantitative dot blot analysis from mattress and carpet dust samples in five buildings designed for low energy use (LEB) and in six control buildings (CB). Inhabitants had received 4 weeks prior to mite measurement a personal validated questionnaire related to the perceived state of health and comfort of living.

RESULTS

Cumulative mite allergen concentration (with Der f 1 as the major contributor) was significantly lower in LEB as compared with CB both in mattresses and in carpets. In contrast, the two categories of buildings did not differ in Bla g 2 and Fel d 1 concentration, in the amount of dust and airborne mould collected. Whereas temperature was higher in LEB, relative humidity was significantly lower than in CB. Perceived overall comfort was better in LEB.

CONCLUSIONS

Major mite allergen Der f 1 preferentially accumulates in buildings not specifically designed for low energy use, reaching levels at risk for sensitization. We hypothesize that controlled mechanical ventilation present in all audited LEB may favour lower air humidity and hence lower mite growth and allergen concentration, while preserving optimal perceived comfort.

Current guidelines for the management of asthma in young children

The diagnosis and management of asthma in young children is difficult, since there are many different wheezy phenotypes with varying underlying aetiologies and outcomes. This review discusses the different approaches to managing young children with wheezy illnesses presented in recently published global guidelines. Four major guidelines published since 2007 are considered. Helpful approaches are presented to assist the clinician to decide whether a clinical diagnosis of asthma can, or should be made in a young child with a recurrent wheezy illness and which treatments would be appropriate, dependent on risk factors, age of presentation, response to initial treatment and safety considerations. Each of the guidelines provide useful information for clinicians assessing young children with recurrent wheezy illnesses. There are differences in classification of the disease and treatment protocols. Although a firm diagnosis of asthma may only be made retrospectively in some cases and there are several effective guidelines to initiating treatment. Consistent review of the need for ongoing treatment with a particular pharmacological modality is essential, since many children with recurrent wheezing in infancy go into spontaneous remission. It is probable that newer biomarkers of airway inflammation will assist the clinician as to when to initiate and when to continue pharmacological treatment in the future.

Improving the management of atopic disease

Asthma, wheeze, eczema, and, to a certain extent, rhinitis are very common conditions among children. The prevalence of allergic disease in the general population has increased alarmingly over the past 25 years, particularly in Western industrialised countries. However, it is important to remember that the symptoms often associated with allergy can have other aetiologies. Evidence suggests that in most circumstances, only 30-40% of chronic allergic-type symptoms are due to allergy. Accurate diagnosis of the presence of allergy is therefore an important issue, particularly given the interventions that such a diagnosis may initiate. In this review, we examine management options for allergy, provide the evidence as to what proportions of patients with common allergic-type symptoms are actually allergic, and list other causes of such symptoms. The importance of allergy testing and the options available are described, particularly with reference to the role of the non-allergist.

Knowledge and expectations of patients receiving aeroallergen immunotherapy

BACKGROUND

Patients receiving aeroallergen immunotherapy frequently have poor knowledge and unfounded expectations of various important aspects of their treatment.

OBJECTIVE

To evaluate patients' knowledge about the content, benefit, and risk related to the aeroallergen immunotherapy that they were receiving.

METHODS

A self-administered questionnaire was distributed to all patients older than 16 years who had undergone aeroallergen immunotherapy for allergic rhinitis at 3 university-affiliated allergy clinics.

RESULTS

A total of 132 patients (77 males and 57 females; mean +/- SD age, 30 +/- 13 years) participated in the study. The mean +/- SD duration of treatment was 30 +/- 60 months. Complete recovery of their allergies was expected by 39% of the patients. One fifth of the study group did not know when improvement should be expected, and 18% anticipated improvement to occur within days or weeks from the initiation of treatment. Only 32% were aware that immunotherapy might have some potential risk or adverse effects, and 24.2% failed to identify at least one of the allergens they were receiving. Patients who were interviewed during their first 6 months of aeroallergen immunotherapy had more knowledge about it than those who had been undergoing long-term treatment.

CONCLUSIONS

There is a grave lack of knowledge and numerous misconceptions among substantial numbers of patients receiving aeroallergen immunotherapy. More educational effort is needed to increase patients' knowledge about immunotherapy before and during aeroallergen immunotherapy to improve their compliance and the success and safety of this therapeutic modality.

Measurement of Dermatophagoides mite allergens on bedding and human skin surfaces

BACKGROUND

The level of the Dermatophagoides mite group 1 (Der 1) allergens in reservoir dust has been used as an index of exposure in most studies. However, the mite allergen level in reservoir dust cannot directly reflect the personal exposure level.

OBJECTIVE

We sought to develop a new method for quantifying the Der 1 allergens on bedding and human skin surfaces as an index of exposure to mite allergens.

METHODS

Samples were obtained with a small adhesive tape from the forearm skin of 30 healthy volunteers and from their regularly used mattresses. The level of Der 1 allergens collected onto the adhesive tape was measured by a newly developed sensitive fluorometric ELISA for Der p 1 and Der f 1.

RESULTS

The Der 1 allergens could be detected in all the samples from bedding surfaces and in 28 of the 30 samples from skin surfaces. The Der 1 levels by adhesive tape sampling from the mattresses correlated with those by reservoir dust sampling. The sampling of the skin and bedding surface with adhesive tape correlated, but skin sampling did not correlate with reservoir sampling.

CONCLUSION

The Der 1 allergens on bedding surfaces and on human skin surfaces could be quantified with a very simple sampling technique. The system developed in this study will provide a new tool for the assessment of mite allergen exposure in daily life.