Review: Measures to control house dust mites are not effective in patients with asthma who are sensitive to mites

Main results 22 studies met the inclusion criteria; 1 study had 3 groups and was treated as 2 trials in the meta-analysis (23 studies involving 686 adults and children). Follow-up ranged from 2 weeks to 1 year (mean 19 wk). 13 studies used physical methods to control mites, with 3 reporting a reduction in mite exposure. 6 studies used chemical methods to control mites; none reported a reduction in mite exposure. 4 studies used a combination of methods, and only 3 reported a reduction in mite exposure. 5 studies did not assess mite exposure. No difference between groups existed in the number of patients who improved after intervention (S studies), asthma symptom improvement (7 studies), PEFR in the morning (10 studies) or evening (6 studies), PC20, or medication use (Table). Heterogeneity existed among trials for asthma symptom improvement^ (P< 0.001). When studies using chemi cal methods to control mite exposure were combined, PEFR in the morning was better for the control group than for the intervention group (standardised mean difference -O.S0, 95% CI -0.9JB to-0.01). >!