Effects of anti-mite measures on children with mite-sensitive asthma: a controlled trial

Environmental influences on childhood asthma: Allergens

Allergen exposure is associated with the development of allergen-specific sensitization, but their relationship is influenced by other contemporaneous exposures (such as microbial exposure) and the genetic predisposition of the host. Clinical outcomes of the primary prevention studies that tested the effectiveness of allergen avoidance in pregnancy and early life on the subsequent development of sensitization and asthma published to date are inconsistent. Therefore, we cannot provide any evidence-based advice on the use of allergen avoidance for the primary prevention of these conditions. The evidence about the impact of allergen exposure among and among sensitized children with asthma is more consistent, and the combination of sensitization and high exposure to sensitizing allergen increases airway inflammation, triggers symptoms, adversely impacts upon disease control, and is associated with poorer lung function in preschool age. However, there are differing opinions about the role of inhalant allergen avoidance in asthma management, and recommendations differ in different guidelines. Evidence from more recent high-quality trials suggests that mite allergen-impermeable bed encasings reduce hospital attendance with asthma attacks and that multifaceted targeted environmental control improves asthma control in children. We therefore suggest a pragmatic approach to allergen avoidance in the management of childhood asthma for clinical practice, including the recommendations to: (1) tailor the intervention to the patient's sensitization and exposure status by using titer of allergen-specific IgE antibodies and/or the size of the skin test as indicators of potential response; (2) use a multifaceted allergen control regime to reduce exposure as much as possible; and (3) start intervention as early as possible upon diagnosis.

Alarm interventions for nocturnal enuresis in children

BACKGROUND

Enuresis (bedwetting) affects up to 20% of five-year-olds and can have considerable social, emotional and psychological effects. Treatments include alarms (activated by urination), behavioural interventions and drugs.

OBJECTIVES

To assess the effects of enuresis alarms for treating enuresis in children.

SEARCH METHODS

We searched the Cochrane Incontinence Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, MEDLINE Epub Ahead of Print, ClinicalTrials.gov, WHO ICTRP, and handsearching of journals and conference proceedings (searched 25 June 2018), and reference lists of relevant articles.

SELECTION CRITERIA

We included randomised or quasi-randomised trials of enuresis alarms or alarms combined with another intervention for treating nocturnal enuresis in children between 5 and 16 years old.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed risk of bias and extracted data.

MAIN RESULTS

We included 74 trials (5983 children). At treatment completion, alarms may reduce the number of wet nights a week compared to control or no treatment (mean difference (MD) -2.68, 95% confidence interval (CI) -4.59 to -0.78; 4 trials, 127 children; low-quality evidence). Low-quality evidence suggests more children may achieve complete response (14 consecutive dry nights) with alarms compared to control or no treatment (RR 7.23, 95% CI 1.40 to 37.33; 18 trials, 827 children) and that more children may remain dry post-treatment (RR 9.67, 95% CI 4.74 to 19.76; 10 trials, 366 children; low-quality evidence). At treatment completion, we are uncertain whether there is any difference between alarms and placebo drugs in the number of wet nights a week (MD -0.96, 95% CI -2.32 to 0.41; 1 trial, 47 children; very low-quality evidence). Alarms may result in more children achieving complete response than with placebo drugs (RR 1.59, 95% CI 1.16 to 2.17; 2 trials, 181 children; low-quality evidence). No trials comparing alarms to placebo reported the number of children remaining dry post-treatment. Compared with control alarms, code-word alarms probably slightly increase the number of children achieving complete response at treatment completion (RR 1.11, 95% CI 0.97 to 1.27; 1 trial, 353 children; moderate-quality evidence) but there is probably little to no difference in the number of children remaining dry post-treatment (RR 0.91, 95% CI 0.79 to 1.05; moderate-quality evidence). Very low-quality evidence means we are uncertain if there are any differences in effectiveness between the other different types of alarm. At treatment completion, alarms may reduce the number of wet nights a week compared with behavioural interventions (waking, bladder training, dry-bed training, and star chart plus rewards) (MD -0.81, 95% CI -2.01 to 0.38; low-quality evidence) and may increase the number of children achieving complete response (RR 1.77, 95% CI 0.98 to 3.19; low-quality evidence) and may slightly increase the number of children remaining dry post-treatment (RR 1.39, 95% CI 0.81 to 2.41; low-quality evidence). The evidence relating to alarms compared with desmopressin in the number of wet nights a week (MD -0.64, 95% CI -1.77 to 0.49; 4 trials, 285 children) and the number of children achieving complete response at treatment completion (RR 1.12, 95% CI 0.93 to 1.36; 12 trials, 1168 children) is low-quality, spanning possible harms and possible benefits. Alarms probably slightly increase the number of children remaining dry post-treatment compared with desmopressin (RR 1.30, 95% CI 0.92 to 1.84; 5 trials, 565 children; moderate-quality evidence). At treatment completion, we are uncertain if there is any difference between alarms and tricyclics in the number of wet nights a week, the number of children achieving complete response or the number of children remaining dry post-treatment, because the quality of evidence is very low. Due to very low-quality evidence we are uncertain about any differences in effectiveness between alarms and cognitive behavioural therapy, psychotherapy, hypnotherapy and restricted diet. Alarm plus desmopressin may reduce the number of wet nights a week compared with desmopressin monotherapy (MD -0.88, 95% CI -0.38 to -1.38; 2 trials, 156 children; low-quality evidence). Alarm plus desmopressin may increase the number of children achieving complete response (RR 1.32, 95% CI 1.08 to 1.62; 5 trials, 359 children; low-quality evidence) and the number of children remaining dry post-treatment (RR 2.33, 95% CI 1.26 to 4.29; 2 trials, 161 children; low-quality evidence) compared with desmopressin alone. Alarm plus dry-bed training may increase the number of children achieving a complete response compared to dry-bed training alone (RR 3.79, 95% CI 1.85 to 7.77; 1 trial, 80 children; low-quality evidence). It is unclear if there is any difference in the number of children remaining dry post-treatment because of the wide confidence interval (RR 0.56, 95% CI 0.15 to 2.12; low-quality evidence). Due to very low-quality evidence, we are uncertain about any differences in effectiveness between alarm plus bladder training versus bladder training alone. Of the 74 included trials, 17 reported one or more adverse events, nine reported no adverse events and 48 did not mention adverse events. Adverse events attributed to alarms included failure to wake the child, ringing without urination, waking others, causing discomfort, frightening the child and being too difficult to use. Adverse events of comparator interventions included nose bleeds, headaches and abdominal pain. There is probably a slight increase in adverse events between code-word alarm and standard alarm (RR 1.34, 95% CI 0.75 to 2.38; moderate-quality evidence), although we are uncertain because of the wide confidence interval. Alarms probably reduce the number of children experiencing adverse events compared with desmopressin (RR 0.38, 95% CI 0.20 to 0.71; 5 trials, 565 children; moderate-quality evidence). Very low-quality evidence means we cannot be certain whether the adverse event rate for alarms is lower than for other treatments.

AUTHORS' CONCLUSIONS

Alarm therapy may be more effective than no treatment in reducing enuresis in children. We are uncertain if alarm therapy is more effective than desmopressin but there is probably a lower risk of adverse events with alarms than with desmopressin. Despite the large number of trials included in this review, further adequately-powered trials with robust randomisation are still needed to determine the full effect of alarm therapy.

A meta-analysis of baseline characteristics in trials on mite allergen avoidance in asthmatics: room for improvement

BACKGROUND

Evidence regarding the clinical effectiveness of mite allergen avoidance for the treatment of asthma is lacking. In previous meta-analyses on mite allergen control, the baseline data were not discussed in detail. This study updates and extends the existing Cochrane review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187), with a focus on baseline asthma outcomes and allergen exposures.

METHODS

We used the existing trials in the original Cochrane review and included newly published studies. The baseline data for the mite allergen load from the mattress, the standardized asthma symptom score (ASS), the forced expiratory volume in 1 s percentage of predicted (FEV1 %pred.), and the histamine provocative concentration causing a 20% drop in FEV1 (PC20) were extracted. First, the mean values of the outcomes were calculated. The influence of the mite allergen load was examined with a random-effect meta-regression using the Metafor package in R.

RESULTS

Forty-five trials were included; 39 trials reported strategies for concurrent bedroom interventions, and 6 trails reported strategies for air purification. The mite allergen load ranged from 0.44 to 24.83 μg/g dust, with a mean of 9.86 μg/g dust (95% CI 5.66 to 14.05 μg/g dust, I2 = 99.8%). All health outcomes showed considerable heterogeneity (standardized ASS mean: 0.13, 95% CI 0.08 to 0.18, I2 = 99.9%; FEV1 %pred. mean: 85.3%, 95% CI 80.5 to 90.1%, I2 = 95.8%; PC20 mean: 1.69 mg/mL, 95% CI 0.86 to 2.52 mg/mL, I2 = 95.6%). The covariate mite allergen load did not significantly influence health outcomes.

DISCUSSION

This meta-analysis shows that mite avoidance studies are characterized by the inclusion of patients with rather mild to moderate asthma and with varying and sometimes negligible levels of allergen exposure. Future studies should focus on patients with severe asthma and increased levels of allergen exposure.

A reintroduction of environmental mite allergen control strategies for asthma treatment and the debate on their effectiveness

Asthma affects three hundred million people worldwide. The effectiveness of house dust mite allergen control for asthma treatment is debatable. One aspect that has been little discussed in existing meta-analyses is the possible role of environmental strategies. Here, we reintroduce the previously defined strategies for mite allergen control and discuss their importance to the debate on clinical effectiveness. The strategy of concurrent bedroom interventions is related to the combined use of a priori defined interventions, while the strategy of exposure-based control relates to the treatment of relevant textiles after assessing exposure. The air purification strategy aims to purify the human breathing zone of airborne allergens. In Western European patient practice, the use of these strategies differs. A post hoc study of the dominant Cochrane review by Gøtzsche and Johansen (Cochrane Database of Systematic Reviews, 2008, Art. No: CD001187) appears to indicate that a majority of the underlying trials reported on the strategy of concurrent bedroom interventions, which were mainly executed in a minimal manner. Some trials have reported on the air purification strategy and may potentially alter the debate on effectiveness. No trial has reported on the strategy of exposure-based control. We therefore hypothesize that the absence of evidence for the effectiveness of mite allergen control for asthma treatment applies to the strategy of concurrent bedroom interventions. The evidence-based effectiveness of the exposure-based control strategy appears to be undetermined. The results of our post hoc reanalysis urge that future meta-analyses of mite allergen control should a priori define the environmental strategy under study. Future trials of mite allergen control are warranted to test the exposure-based strategy as well as the sparsely tested strategy of air purification.

House dust mite control measures for asthma: systematic review

The major allergen in house dust comes from mites. We performed a systematic review of the randomized trials that had assessed the effects of reducing exposure to house dust mite antigens in the homes of people with mite-sensitive asthma, and had compared active interventions with placebo or no treatment. Fifty-four trials (3002 patients) were included. Thirty-six trials assessed physical methods (26 mattress covers), 10 chemical methods and eight a combination of chemical and physical methods. Despite the fact that many trials were of poor quality and would be expected to exaggerate the reported effect, we did not find an effect of the interventions. For the most frequently reported outcome, peak flow in the morning (1565 patients), the standardized mean difference was 0.00 (95% confidence interval (CI) -0.10 to 0.10). There were no statistically significant differences in number of patients improved (relative risk 1.01, 95% CI 0.80-1.27), asthma symptom scores (standardized mean difference -0.04, 95% CI -0.15 to 0.07) or in medication usage (standardized mean difference -0.06, 95% CI -0.18 to 0.07). Chemical and physical methods aimed at reducing exposure to house dust mite allergens cannot be recommended.

House dust mite control measures for asthma

EDITORIAL NOTE

This 2011 review predates current reporting standards and methodological expectations for Cochrane Reviews. It should not be used for clinical decision‐making.

BACKGROUND

The major allergen in house dust comes from mites. Chemical, physical and combined methods of reducing mite allergen levels are intended to reduce asthma symptoms in people who are sensitive to house dust mites.

OBJECTIVES

To assess the effects of reducing exposure to house dust mite antigens in the homes of people with mite-sensitive asthma.

SEARCH STRATEGY

PubMed and The Cochrane Library (last searches Nov 2007), reference lists.

SELECTION CRITERIA

Randomised trials of mite control measures vs placebo or no treatment in people with asthma known to be sensitive to house dust mites.

DATA COLLECTION AND ANALYSIS

Two authors applied the trial inclusion criteria and evaluated the data. Trial authors were contacted to clarify information.

MAIN RESULTS

Fifty-four trials (3002 patients) were included. Thirty-six trials assessed physical methods (26 mattress encasings), 10 chemical methods, and 8 a combination of chemical and physical methods. Despite the fact that many trials were of poor quality and would be expected to exaggerate the reported effect, we did not find an effect of the interventions. For the most frequently reported outcome, peak flow in the morning (1565 patients), the standardised mean difference was 0.00 (95% confidence interval (CI) -0.10 to 0.10). There were no statistically significant differences either in number of patients improved (relative risk 1.01, 95% CI 0.80 to 1.27), asthma symptom scores (standardised mean difference -0.04, 95% CI -0.15 to 0.07), or in medication usage (standardised mean difference -0.06, 95% CI -0.18 to 0.07).

AUTHORS' CONCLUSIONS

Chemical and physical methods aimed at reducing exposure to house dust mite allergens cannot be recommended. It is doubtful whether further studies, similar to the ones in our review, are worthwhile. If other types of studies are considered, they should be methodologically rigorous and use other methods than those used so far, with careful monitoring of mite exposure and relevant clinical outcomes.

Effect of home environment control on children with atopic or non-atopic asthma

BACKGROUND

Although allergen avoidance is known to be important for treating atopic diseases, there is a very limited amount of time for clinical education of patients on this topic.

METHODS

We compared the effect of the thorough home visit counseling (>60 minutes per visit) for avoiding house dust mites (HDMs) with that of regular guidance in our clinics (10 minutes per patient). We enrolled 36 children with asthma (7 years of age or younger; mean, 3.8) in this study under an informed consent. After enrolling the 24 patients for the home visit, 12 families were enrolled as controls for the regular clinical guidance. Between June 1995 and June 1996, we visited the homes of 24 children with asthma enrolled in this study every month and performed a thorough HDM-avoidance counseling of more than 60 minutes (home visit counsel) at each visit. We compared the effects of this counseling with those of the regular clinical guidance given (10 minutes per patient) to the remaining 12 children with asthma. We also evaluated the effect of home visit counseling on children of two subgroups, i.e., an atopic (with positive IgE antibody against HDM) and a non-atopic (without detectable IgE antibodies against 8 common allergens) subgroup.

RESULTS

Home visit counseling markedly reduced the frequencies of asthma attacks (p < 0.000001), the required theophylline dosages (p < 0.0005), and the levels of HDM allergens (p < 0.0005) in the atopic subgroups, whereas the effect of regular counseling on these 3 items was relatively less (p < 0.05 or not significant). Surprisingly, home visit counseling also markedly reduced the asthma attacks (p < 0.00001) and theophylline dosages (p < 0.00001) of children with non-atopic asthma.

CONCLUSIONS

These results suggest that thorough allergen avoidance counseling is effective for children with non-atopic asthma as well as atopic asthma.

House dust mite control measures for asthma

BACKGROUND

The major allergen in house dust comes from mites. Chemical, physical and combined methods of reducing mite allergen levels are intended to reduce asthma symptoms in people who are sensitive to house dust mites.

OBJECTIVES

To assess the effects of reducing exposure to house dust mite antigens in the homes of people with mite-sensitive asthma.

SEARCH STRATEGY

Cochrane Airways Group trials register, and PubMed and The Cochrane Library (last searches June 2004), reference lists.

SELECTION CRITERIA

Randomised trials of mite control measures vs placebo or no treatment in asthmatic people known to be sensitive to house dust mites.

DATA COLLECTION AND ANALYSIS

Two reviewers applied the trial inclusion criteria, assessed their quality and extracted the data independently. Study authors were contacted to clarify information.

MAIN RESULTS

Forty-nine trials (2733 patients) were included; the number of patients has more than doubled since the last version of this review. Thirty-one trials assessed physical methods, ten assessed chemical methods, and eight a combination of chemical and physical methods. Despite the fact that many trials were of poor quality and would be expected to exaggerate the reported effect, we did not find an effect of the interventions. For the most frequently reported outcome, peak flow in the morning (1339 patients), the standardised mean difference was -0.02 (95% confidence interval (CI) -0.13 to 0.08). There were no statistically significant differences either in number of patients improved (relative risk 1.01, 95% CI 0.80 to 1.27), asthma symptom scores (standardised mean difference -0.01, 95% CI -0.10 to 0.13), or in medication usage (standardised mean difference -0.05, 95% CI -0.18 to 0.09).

REVIEWERS' CONCLUSIONS

Chemical and physical methods aimed at reducing exposure to house dust mite allergens cannot be recommended. It is doubtful whether further studies, similar to the ones in our meta-analysis, are worthwhile. If other types of studies are considered, they should be methodologically rigorous and use other methods than those used so far, with careful monitoring of mite exposure and relevant clinical outcomes.

The effects of housing interventions on child health

Housing hazards contribute to considerable morbidity and mortality among millions of children each year in the US, but few interventions are proven to control asthma and lead poisoning. Moreover, there is little evidence that many of the current recommendations to control residential hazards are safe and efficacious. The only interventions that have been found to work consistently are home visitation programs and home modification, such as installment of window guards and carpet removal. Altering the environment to protect the health of children requires pediatrician intervention. New models of cooperation between pediatricians and public health agencies must deal with residential hazards in an integrated manner and cannot be focused on one disease process or one method at a time. With research in more effective environmental interventions and pediatric-public-health partnerships, primary and secondary prevention of diseases from residential hazards may become a reality in the future.

The role of house dust mite elimination in the management of childhood asthma: an unresolved issue

Indoor allergens are likely to be direct environmental causes of asthma and mite exposure, and sensitization is the most important environmental risk factor for childhood asthma in temperate zones. Analagous to occupational asthma, allergen avoidance in asthmatic children sensitized and exposed to mite allergens is associated with a reduction in airway hyperresponsiveness and symptoms associated with improvement in lung function. The long-term effect of this strategy needs to be prospectively evaluated considering both the timing and duration of exposure, as well as the timing and duration of removal. In order to be successful, it is important to achieve and maintain a major reduction on allergen levels, for a long period of time.

Controlling indoor allergens

OBJECTIVES

Reading of this article reinforces the reader's knowledge of the role of allergen exposure in relation to asthma and its severity, as well as the relevance of allergen avoidance in the treatment of asthma.

DATA SOURCES

Initial literature search for existing evidence-based guidelines, reviews, and meta-analyses was carried out, and further literature searches were performed to review individual randomized controlled trials. Evidence level was graded according to the Scottish Intercollegiate Guidelines Network recommendations.

RESULTS

There is good evidence for the link between mite and cockroach allergen exposure and sensitization, and between sensitization and asthma. For pet allergens, some studies found that exposure to pets in early life was associated with specific immunoglobulin E sensitization and allergic disease later in childhood, whereas others reported a protective effect. The effectiveness of allergen reduction in the treatment of asthma is suggested by studies in which the patients improve substantially when moved into the low-allergen environment of hospitals or high-altitude sanatoria. Because of limitations in the design of the most clinical of studies, we do not yet have a conclusive answer on the effectiveness of domestic aeroallergen avoidance.

CONCLUSIONS

Minimizing the impact of identified environmental risk factors is an important first step to reduce the severity of asthma. Although environmental control is difficult, it should be an integral part of the overall management of sensitized patients. However, what is unclear is which patients would benefit and by how much, and whether the intervention is cost-effective. These questions will be answered satisfactorily only by large randomized trials.

The role of intervention in established allergy: avoidance of indoor allergens in the treatment of chronic allergic disease

Avoidance of exposure to indoor allergens is an important element in the treatment of allergic disease. The results of several studies provide strong evidence in support of a role for allergen avoidance; however, strategies that optimize allergen reduction in houses have not been determined. Complex issues regarding the efficacy of physical and chemical measures that target house dust mite, pet, and cockroach allergens in the home are discussed. The greatest challenge is to educate allergic patients so that they can play an important role in controlling their own disease.

Canadian Asthma Consensus Report, 1999. Canadian Asthma Consensus Group

OBJECTIVES

To provide physicians with current guidelines for the diagnosis and optimal management of asthma in children and adults, including pregnant women and the elderly, in office, emergency department, hospital and clinic settings.

OPTIONS

The consensus group considered the roles of education, avoidance of provocative environmental and other factors, diverse pharmacotherapies, delivery devices and emergency and in-hospital management of asthma.

OUTCOMES

Provision of the best control of asthma by confirmation of the diagnosis using objective measures, rapid achievement and maintenance of control and regular follow-up.

EVIDENCE

The key diagnostic and therapeutic recommendations are based on the 1995 Canadian guidelines and a critical review of the literature by small groups before a full meeting of the consensus group. Recommendations are graded according to 5 levels of evidence. Differences of opinion were resolved by consensus following discussion.

VALUES

Respirologists, immunoallergists, pediatricians and emergency and family physicians gave prime consideration to the achievement and maintenance of optimal control of asthma through avoidance of environmental inciters, education of patients and the lowest effective regime of pharmacotherapy to reduce morbidity and mortality.

BENEFITS, HARMS AND COSTS

Adherence to the guidelines should be accompanied by significant reduction in patients' symptoms, reduced morbidity and mortality, fewer emergency and hospital admissions, fewer adverse side-effects from medications, better quality of life for patients and reduced costs.

RECOMMENDATIONS

Recommendations are included in each section of the report. In summary, after a diagnosis of asthma is made based on clinical evaluation, including demonstration of variable airflow obstruction, and contributing factors are identified, a treatment plan is established to obtain and maintain optimal asthma control. The main components of treatment are patient education, environmental control, pharmacotherapy tailored to the individual and regular follow-up.

VALIDATION

The recommendations were distributed to the members of the Canadian Thoracic Society Asthma and Standards Committees, as well as members of the board of the Canadian Thoracic Society. In addition, collaborating groups representing the Canadian Association of Emergency Physicians, the Canadian College of Family Physicians, the Canadian Paediatric Society and the Canadian Society of Allergy and Immunology were asked to validate the recommendations. The recommendations were discussed at regional meetings throughout Canada. They were also compared with the recommendations of other similar groups in other countries. DISSEMINATION AND IMPLEMENTATION: An implementation committee has established a strategy for disseminating these guidelines to physicians, other health professionals and patients and for developing tools and means that will help integrate the recommendations into current asthma care. The plan is outlined in this report.

Chicago community-based asthma intervention trial: feasibility of delivering peer education in an inner-city population

The most effective means of educating children with asthma and their families has not been clearly demonstrated in previous studies. Peer education is uniquely suited to the complex problems encountered in underserved populations. The purpose of this study was to show the feasibility of delivering a peer education program for children with asthma and the effect of the program on indoor allergen levels in an inner-city population in Chicago. Overall, the program was well received. Baseline allergen levels were consistent with some previous studies in showing low levels of mite allergens and high levels of cockroach allergens, with 79.6% of samples having levels > 8 U/g. A total of 28.2% of samples had cat allergen levels > 2 microg/g, although only 9.7% of homes had cats, confirming previous reports that cat allergen is ubiquitous. Mold levels were seasonal, with the highest levels in the summer. Results from this study suggest that intervention programs should focus more on elimination of cockroaches than was previously appreciated, while minimizing the use of pesticides, and on identification of the sources of cat allergen. Structural and psychosocial issues in homes need to be addressed in future studies. This study has demonstrated the feasibility of delivering peer education in a inner-city population and highlighted the need for comprehensive intervention strategies addressing complex issues facing underserved neighborhoods.

Complete mattress encasing is not superior to partial encasing in the reduction of mite allergen

BACKGROUND

Partial mattress encasing was found to be effective in reducing exposure to mite allergen in our previous investigation. We aimed to compare the short-term efficacy of partial and complete mattress encasing and to study mite-allergen levels within these mattresses.

METHODS

Thirty-one mattresses with high mite-allergen content were selected and were randomized into one of three study groups (10 for the control group [CG], 11 for the partial encasing group [PE], and 10 for the complete encasing group [CE]). A special mite-impermeable membrane was used. In the PE group, mattresses were encased on tops and sides only, whereas complete mattress encasement was undertaken in the CE group. Regular bedsheets were applied to all groups. Dust samples were collected over bedsheets at baseline and at months 3 and 6, and over mattresses at baseline and at the end of the study. Group I mite allergens in these samples were measured and compared.

RESULTS

At baseline, mattress mite allergens were similar in all groups (P=0.84). Mite allergen at the surfaces of bedsheets (over membranes) from both encasing groups were significantly reduced as compared to the CG group (P=0.003). Such reduction was maintained throughout the 6-month study. At the end of the study, mite antigens within mattresses in the CG and CE groups were increased as compared to baselines, whereas a decrease was observed in the PE group. Significant difference was observed only between the CG and PE groups (P=0.006).

CONCLUSIONS

Mattress encasing with a special membrane in this study was highly efficacious in the reduction of mite allergen (>90%). However, with complete encasing, mite allergens within mattresses were increased at the end of the study. Complete mattress encasing in a tropical environment does not offer any advantage over partial encasing.

House dust mite exposure as a risk factor for asthma: benefits of avoidance

There is a dose-response relation between the level of exposure to house dust mite allergen and the risk of acquiring sensitization to this allergen as well as the risk of developing asthma. This relation is apparent at levels of exposure below 10 microg/g. In communities where nearly all houses have house dust mite allergen levels above this threshold, all susceptible individuals will be affected, and the relation to house dust mite exposure will not be apparent. Although these observational data would suggest that reducing exposure to house dust mite allergen should lessen the risk of developing sensitization and asthma, definitive evidence from randomized controlled trials is not yet available. Of the many clinical trials of house dust mite avoidance as therapy for asthma, only a few have produced sustained, substantial reductions in allergen levels in the bed. These effective interventions all included allergen-impermeable encasement of mattresses along with other strategies. In most trials where allergens levels were successfully reduced, there were clinical benefits for patients with asthma.

Diagnosis and management of rhinitis: complete guidelines of the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology. American Academy of Allergy, Asthma, and Immunology

This document contains complete guidelines for diagnosis and management of rhinitis developed by the Joint Task Force on Practice Parameters in Allergy, Asthma and Immunology, representing the American Academy of Allergy, Asthma and Immunology, the American College of Allergy, Asthma and Immunology and the Joint Council on Allergy, Asthma and Immunology. The guidelines are comprehensive and begin with statements on clinical characteristics and diagnosis of different forms of rhinitis (allergic, non-allergic, occupational rhinitis, hormonal rhinitis [pregnancy and hypothyroidism], drug-induced rhinitis, rhinitis from food ingestion), and other conditions that may be confused with rhinitis. Recommendations on patient evaluation discuss appropriate use of history, physical examination, and diagnostic testing, as well as unproven or inappropriate techniques that should not be used. Parameters on management include use of environmental control measures, pharmacologic therapy including recently introduced therapies and allergen immunotherapy. Because of the risks to patients and society from sedation and performance impairment caused by first generation antihistamines, second generation antihistamines that reduce or eliminate these side effects should usually be considered before first generation antihistamines for the treatment of allergic rhinitis. The document emphasizes the importance of rhinitis management for comorbid conditions (asthma, sinusitis, otitis media). Guidelines are also presented on special considerations in patients subsets (children, the elderly, pregnancy, athletes and patients with rhinitis medicamentosa); and when consultation with an allergist-immunologist should be considered.

House dust mite control measures in the management of asthma: meta-analysis

OBJECTIVE

To determine whether patients with asthma who are sensitive to mites benefit from measures designed to reduce their exposure to house dust mite antigen in the home.

DESIGN

Meta-analysis of randomised trials that investigated the effects on asthma patients of chemical or physical measures to control mites, or both, in comparison with an untreated control group. All trials in any language were eligible for inclusion.

SUBJECTS

Patients with bronchial asthma as diagnosed by a doctor and sensitisation to mites as determined by skin prick testing, bronchial provocation testing, or serum assays for specific IgE antibodies.

MAIN OUTCOME MEASURES

Number of patients whose allergic symptoms improved, improvement in asthma symptoms, improvement in peak expiratory flow rate. Outcomes measured on different scales were combined using the standardised effect size method (the difference in effect was divided by the standard deviation of the measurements).

RESULTS

23 studies were included in the meta-analysis; 6 studies used chemical methods to reduce exposure to mites, 13 used physical methods, and 4 used a combination. Altogether, 41/113 patients exposed to treatment interventions improved compared with 38/117 in the control groups (odds ratio 1.20, 95% confidence interval 0.66 to 2.18). The standardised mean difference for improvement in asthma symptoms was -0.06 (95% confidence interval -0.54 to 0.41). For peak flow rate measured in the morning the standardised mean difference was -0.03 (-0.25 to 0.19). As measured in the original units this difference between the treatment and the control group corresponds to -3 l/min (95% confidence interval -25 l/min to 19 l/min). The results were similar in the subgroups of trials that reported successful reduction in exposure to mites or had long follow up times.

CONCLUSION

Current chemical and physical methods aimed at reducing exposure to allergens from house dust mites seem to be ineffective and cannot be recommended as prophylactic treatment for asthma patients sensitive to mites.

Clinical effects of benzyl benzoate in the prevention of house-dust-mite allergy. Results of a prospective, double-blind, multicenter study

The efficacy of the acaricide benzyl benzoate as an additive to a chemically and technically defined cleaning substance (Acarosan) was tested in a multicentric, prospective, randomized, controlled study on 118 outpatients with bronchial asthma due to house-dust-mite allergy. Subjective reports from patients and doctors revealed an improvement in clinical complaints in more than 50%, with only small differences between the verum and the placebo group. Objective parameters such as titrated skin tests, RAST, and bronchial challenge tests with histamine and Dermatophagoides pteronyssinus (D. pt.) did not reveal any significant changes either during the year of testing or between the two groups. A clinical improvement as observed in either group could not be assessed by objective parameters. Additional questions as to the merits of the possible prophylactic use of benzyl benzoate over more than 1 year remain unanswered.

Variability and repeatability of house dust mite allergen measurement: implications for study design and interpretation

BACKGROUND

To interpret individual measurements of house dust mite (HDM) allergen and to design and analyse HDM studies it is necessary to quantify the variability which is inherent in the measurement of this exposure.

OBJECTIVE

To estimate the repeatability of one method of HDM allergen measurement.

METHODS

We analysed data from one or more HDM allergen measurements in 215 houses included in four previous studies conducted in Sydney (a high allergen environment) and Busselton, Western Australia (a moderate allergen environment). Samples were collected from the bed by vacuuming above and below the sheets and inside the pillow case and from the bedroom and living room floors by vacuuming a 1 m2 area for 1 min. Extracts from aliquots of fine dust from each sample were assayed for HDM allergen Der p I using a monoclonal antibody enzyme linked immunosorbent assay (ELISA). The values for HDM allergen were positively skewed and the suitability of a log transformation was established by the resulting normal distribution and stable within-site variance.

RESULTS

The range of single determination (within which the true value lies with 95% certainty) was 3.1-fold for samples from the bed and 3.5-fold for samples from the floor. The coefficient of repeatability (the ratio beyond which a change between two estimates is established with 95% certainty) was 4.9 for the bed and 5.8 for the floor.

CONCLUSION

We estimate that, to detect a twofold difference or change in allergen levels, 35 houses per group will be required in cross-sectional studies and 30 houses per group in parallel-group, randomized controlled trials. We recommend that beds be sampled by collecting dust from the layer of bedding below the bottom sheet. A single site within the bedroom floor may be taken as representative of this site but this is not true for the living-room floor.

Clinical efficacy of reduction in house-dust mite exposure in specially designed, mechanically ventilated "healthy" homes

In temperate climates, energy-conserving measures may increase indoor humidity, enhancing house-dust mite (HDM) growth. Movement of families to "healthy" homes with mechanical ventilation systems reduced HDM exposure. The effect on asthma control of moving to the "healthy" homes was studied in 14 asthmatic patients allergic to HDM. Base-line evaluations of lung function, asthma symptoms, and medication requirements were made before moving and again after 5 and 15 months' residence. A control group of 11 mite-sensitive asthmatic patients who did not move were examined contemporaneously with the study group at base line and at the first follow-up investigation. After 5 months, the residents of the "healthy" homes improved in forced expiratory volume in 1 s (FEV1), medicine score, and serum IgE. These changes were significantly different from control group measurements. After 15 months, statistically significant improvements from base line were found in FEV1, average daily peak expiratory flow values, medicine score, symptom score, and serum IgE. Insignificant trends toward improvement were seen in provocation concentration of histamine and blood eosinophils. A significant relation was found between reduction in medicine score and fall in HDM exposure. The present study shows that a specific HDM-avoidance procedure can result in an overall, clinical improvement in HDM-sensitive asthmatic patients.

House-dust mite exposure reduction in specially designed, mechanically ventilated "healthy" homes

Exposure to house-dust mites (Dermatophagoides spp.) was investigated in 30 asthmatic patients before and after moving to homes with mechanical ventilation systems. Median house-dust mite concentration was 110 mites per gram of mattress dust at the initial investigation and 20 mites per gram at the first follow-up after a mean of 4.7 months in the new homes. This was lower (P < 0.05) than counts in a control group of 23 asthmatic patients that had unchanged counts. At a second follow-up, after 15.0 months, mite counts in the study group were further reduced (P < 0.01) from initial values. Among 16 patients, with initial mite counts above the recommended threshold limit value (TLV) of 100 mites per gram of dust, the mite counts fell, in most cases, below this TLV. Air-exchange rates increased (P < 0.001) from a median value of 0.40 air changes per hour (ach) to 1.52 ach at the second follow-up investigation. Furthermore, a reduction (P < 0.01) was found in indoor absolute air humidity, with a median value of 5.6 g of water/kg. No such changes were found in the control group. The present study indicates that reduction of air humidity through an increased supply of fresh air may significantly diminish and, in some cases, even eliminate house-dust mites in homes.

Mite (Der p 1, Der f 1) and cat (Fel d 1) allergens in the homes of babies with a family history of allergy

Carpet and floor dust samples were collected in four different seasons, from 39 Swedish homes of babies with a family history of allergy. House-dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen contents were determined by mab ELISA, and the levels were related to various environmental factors. Both mite and cat antigens were detected in 94% of the samples and in all homes, but the levels were low (Der p 1, range 15 ng-1944 ng/g fine dust; Der f 1, range 14 ng-264 ng/g of fine dust; Fel d 1, range 16 ng-3120 ng/g fine dust). Mite-allergen levels were significantly higher (P < 0.001) in floor dust than in carpets, and D. pteronyssinus predominated. In contrast, the levels of cat antigen were significantly (P < 0.05) higher in carpets than in floor dust. There was no clear relation between mite-allergen levels and type of house, except that the higher values were found in homes with dampness problems. Cat-allergen levels were higher than total mite-allergen content, and the highest levels were found in homes with a cat (P < 0.05). Rather high concentrations of cat allergen were also found in homes without a cat, which may explain why cat sensitization is so common in Sweden. As the prevalence of house-dust mite sensitivity is increasing in Swedish children, and as the individual patient threshold for eliciting symptoms varies, we suggest that sensitization may possibly occur at a lower exposure level than generally accepted as risk level for sensitization (2 micrograms/g dust).

Allergen avoidance in the homes of atopic asthmatic children: the effect of Allersearch DMS

Allersearch DMS (an alcohol based purified benzyltannate complex) is an acaricide with allergen denaturing properties. The living rooms in the homes of 16 atopic asthmatic children were thoroughly cleaned and treated with Allersearch DMS and the effect on allergen concentrations in carpet and soft-furnishing dusts was determined. The skin-test reactivity of the children to their own dust, collected before and after treatment, was compared. In 13 of the 16 homes the concentration of major house dust mite allergen Der p I was reduced in the carpet dust after treatment (P < 0.001) and in 11 homes major cat allergen Fel d I was reduced (P = 0.03). Changes in allergen concentrations in soft-furnishing dusts were not significant. Control homes, which were cleaned but not treated, showed no significant difference in allergen concentrations. There were highly significant reductions in skin-test reactivity to both types of dust after treatment (P < 0.004, P < 0.008) suggesting an effect of the compound on allergens other than those individually monitored. The change in skin-test response to soft-furnishing correlated significantly (P < 0.05) with the number of individual sensitivities detected in each child. Controlled clinical trials of the effect of Allersearch DMS as part of an allergen avoidance study are now necessary.

House-dust mites and associated environmental conditions in Danish homes

The concentration of house-dust mites (Dermatophagoides pteronyssinus) was investigated in 96 Danish homes with one or more members suffering from asthma. The air-exchange rates, humidity, and temperature were measured in all the homes. A positive correlation was found between indoor air humidity and mite concentration (P < 0.01), and an inverse correlation (P = 0.027) between house-dust mite concentration and indoor air-exchange was found. Homes of mite-allergic persons had a higher concentration of house-dust mites than did those of the non-mite-allergic group. House-dust mite concentration was above the proposed limit of 10 mites/0.1 g dust in 76% of the homes of persons allergic to mites and in 48% of the homes of nonsensitive persons. The high proportion of homes infested with house-dust mites suggests an increased prevalence of house-dust mites in Danish homes. The results support the concept that reduced ventilation in homes involves a risk of increased house-dust mite exposure.

Concentrations of the domestic house dust mite allergen Der p I after treatment with solidified benzyl benzoate (Acarosan) or liquid nitrogen

BACKGROUND

Various methods of killing the house dust mite to reduce exposure to allergen are being promoted even though complete data on their effects on allergen concentrations are not available. A study was designed to measure the concentrations of the main house dust mite allergen Der pI in homes treated with either solidified benzyl benzoate (Acarosan) or liquid nitrogen.

METHODS

Der pI concentrations were measured in dust collected from mattresses, bedroom carpets, and living room carpets in 10 houses treated with Acarosan and 10 houses treated with liquid nitrogen. Samples were collected before the treatment (in July 1990) and three and six months afterwards (October 1990 and January 1991). Forty untreated houses were concurrently sampled as controls.

RESULTS

Der pI concentrations were similar in the three groups at baseline. No significant fall was seen in either of the two treated groups three or six months after treatment. Concentrations in the control houses increased significantly--twofold to threefold in dust sampled from mattresses and bedroom carpets between baseline and October 1990. This increase was not seen in either of the treated groups of houses, but there was no significant difference in the Derp pI concentrations in these houses and the control houses from any site at any time point.

CONCLUSIONS

Neither Acarosan nor liquid nitrogen reduced the concentrations of Der pI for as long as six months after application. A small effect was probably present as the rise seen in control houses in the three month samples was not found in the treated houses. This effect, however, is likely to be of little clinical importance and also to be transient as the trend was lost by six months.

Allergen exposure and control

Allergens produced by the house dust mites (family Pyroglyphidae) are probably the single most important allergens associated with asthma world wide. If exposure to these allergens in houses could be sufficiently reduced, then asthma symptoms may be markedly reduced and even prevented from being initiated. Only about half of the many attempts to reduce mite allergens in houses have shown any clinical benefit. One reason may be that exposure was not reduced enough--however exposure to mite allergens has never been measured in any trial. This review summarises previous allergen control trials and then provides an outline of allergen exposure, including the nature of exposure, the analytical methods available and the recognised risks of allergen exposure. This provides a perspective to evaluate the individual methods used to kill mites and to reduce exposure to the allergens. The object is to provide a framework to improve and develop allergen avoidance as an effective component of asthma management.

House dust acarofauna and Der p I equivalent in Australia: the relative importance of Dermatophagoides pteronyssinus and Euroglyphus maynei

The acarofauna and Der p I allergen concentrations in dust samples from mattresses and lounge room carpets obtained from 20 homes from two coastal cities. Perth and Bunbury, were determined. All samples were shown to contain mites and the geometric mean numbers of total mites/g of mattress and carpet dust for Perth and Bunbury were 480 and 263, and 585 and 992, respectively. Carpets from both centres had a significantly (P less than 0.02) greater mean number of mite species (Perth 9.1, Bunbury 9.0) than mattresses (Perth 5.2, Bunbury 5.7). The predominant mite species were D. pteronyssinus, E. maynei and Tarsonemus spp. D. farinae was found to be absent from all dust samples examined. E. maynei was present in the 10 Bunbury homes and in 50% of the Perth homes, ranging from 0 to 81% of mites identified. The arithmetic mean Der p I concentrations in the mattresses and carpets in Perth and Bunbury were 4.2 and 4.1, and 3.8 and 9.2 micrograms/per gram of fine dust, respectively, and Der p I concentration correlated with mite counts (r = 0.75; P less than 0.001). The concentration of Der p I equivalent per 100 mites was 1.5 micrograms. The data are consistent with the view that asthmatic patients in Western Australia have significant exposure to a variety of house dust mites and that E. maynei may be clinically significant.

Clinical evaluation of a double-blind dust-mite avoidance trial with mite-allergic rhinitic patients

Inheritance and allergen exposure are key factors in the development and the course of atopic allergy, expressed as conjunctivitis, rhinitis, asthma or dermatitis. This study concerns the clinical significance of mite and mite-allergen avoidance measures based on intensive cleaning with acaricide (solidified benzylbenzoate) added (10 dwellings), and without biocidal activity (10 other homes) as a control in a double-blind trial with matched pairs. Twenty subjects with persisting rhinitic complaints were selected. They lived in 20 different dwellings and were all sensitized to pyroglyphid mites; 12 of them were also sensitized to stored product mites (Acari). Daily symptoms and medication score, guanine and dust exposure, total and mite-specific IgE in serum, eosinophilia in the blood and in the nasal smear, intracutaneous tests with house dust mite and storage mite extracts were compared in both pairs and groups. Acarological data, physiochemical aspects and exposure assessment are discussed in detail elsewhere. Symptom scores dropped significantly, as did the total IgE and exposure to dust and mite products in the acaricidal cleaner treatment group. After 1 year, the daily symptoms median was 47% (P = 0.025), total IgE was 38% (P = 0.0049), and exposure to dust and mite products (guanine exposure) was 53% (P = 0.0449) better or lower than in the controls. Intensive cleaning, without acaricidal treatment performed twice a year, resulted in clinical improvement in four out of 10 subjects, of whom none became free of complaints. In the Acarosan treatment group (cleaning + benzylbenzoate) eight out of 10 subjects improved, in three cases subjective symptoms disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonpharmacologic means of preventing asthma

Cessation of smoking in the home is one of the most important nonpharmacologic actions to be recommended. There is a highly significant increase in wheezing, coughing, and respiratory infections in children with smoking mothers, and this increase is directly proportional to the number of cigarettes smoked. Cord blood IgE levels are increased in babies whose mothers smoke during pregnancy. Other agents, such as sulpur dioxide and chemical pollutants from industrial processes may play a role in the development or exacerbation, of asthma symptoms and should be avoided. One of the most interesting areas in food allergy is whether breast feeding causes sensitization or induces tolerance in infants to foods ingested by the mother. There is an increase in asthma in second-generation immigrant populations who are exposed, from birth, to the Western style of living which increases their exposure to house dust mite. Several studies have shown that month of birth is important in the development of specific allergies, for example, in the incidence of birch pollen allergy in Scandinavia. The presence of a pet in the home at birth is associated with a greater incidence of allergy to that animal. Our study in asthmatic children has shown a strong association (p less than 0.001) between the presence of allergens in the air in their homes (sampled retrospectively in the month of birth) with a positive skin test to those allergens.(ABSTRACT TRUNCATED AT 250 WORDS)