| Sumario: | Question: Is a reduction in exposure to dust mite antigen in the home effective for patients with asthma who are sensitive to mites? Data sources: Studies were identified by searching the the Cochrane Airways Group databases, which contain citations from CINAHL, Medline, and Embase/Excerpta Medica. Respiration and Clinical and Experimental Allergy were handsearched (1980-96). Bibliographies of relevant articles were scanned, and primary authors were contacted for additional data. Study selection: Studies in any language were selected if they were randomised controlled trials that compared chemical or physical measures for controlling mites in the home with no treatment in patients with bronchial asthma. A diagnosis of asthma by a physician and confirmation of sensitisation to mites were required. Data extraction: 2 authors extracted data on subjective wellbeing, improvement in asthma symptoms, medication to control asthma, number of sick days, number of unscheduled visits to a physician or hospital, FEV1 (forced expiratory volume in 1 sec), peak expiratory flow rate, provocative concentration that causes a 20% decrease in FEV1 (PC[20]), and results of skin prick testing. Main results: 23 studies involving 686 adults and children met the inclusion criteria (1 study that had 3 groups was treated as 2 separate trials). Follow up ranged from 2-52 weeks (mean 18.6 wks). 13 studies used physical methods to control mites, and 3 reported a reduction in mite exposure (5 studies did not assess mite exposure). 6 studies used chemical methods to control mites, and none reported a reduction in mite exposure. 4 studies used a combination of methods, and 3 reported a reduction in mite exposure. Groups did not differ for number of patients who improved after intervention (5 studies), asthma symptom improvement (7 studies), peak expiratory flow rate in the morning (10 studies) or evening (6 studies), PC[20] (8 studies), or medication use (6 studies). Heterogeneity existed among trials for asthma symptom improvement (p < 0.001). Conclusion: A reduction in exposure to dust mite antigen in the home does not lead to an improvement in patients with asthma who are sensitive to mites. [Original article accession number: 1998074109 (clinical trial, research, tables/charts) and 2000006662 (research, systematic review, tables/charts)
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