PT - JOURNAL ARTICLE AU - Burr, M L AU - Matthews, I P AU - Arthur, R A AU - Watson, H L AU - Gregory, C J AU - Dunstan, F D J AU - Palmer, S R TI - Effects on patients with asthma of eradicating visible indoor mould: a randomised controlled trial AID - 10.1136/thx.2006.070847 DP - 2007 Sep 01 TA - Thorax PG - 767--772 VI - 62 IP - 9 4099 - http://thorax.bmj.com/content/62/9/767.short 4100 - http://thorax.bmj.com/content/62/9/767.full SO - Thorax2007 Sep 01; 62 AB - Background: It is not clear whether associations between respiratory symptoms and indoor mould are causal. A randomised controlled trial was conducted to see whether asthma improves when indoor mould is removed. Methods: Houses of patients with asthma were randomly allocated into two groups. In one group, indoor mould was removed, fungicide was applied and a fan was installed in the loft. In the control group, intervention was delayed for 12 months. Questionnaires were administered and peak expiratory flow rate was measured at baseline, 6 months and 12 months. Results: Eighty-one houses were allocated to the intervention group and 83 to the control group; 95 participants in 68 intervention houses and 87 in 63 control houses supplied follow-up information. Peak expiratory flow rate variability declined in both groups, with no significant differences between them. At 6 months, significantly more of the intervention group showed a net improvement in wheeze affecting activities (difference between groups 25%, 95% CI 3% to 47%; p = 0.028), perceived improvement of breathing (52%, 95% CI 30% to 74%; p<0.0001) and perceived reduction in medication (59%, 95% CI 35% to 81%; p<0.0001). By 12 months the intervention group showed significantly greater reductions than the controls in preventer and reliever use, and more improvement in rhinitis (24%, 95% CI 9% to 39%; p = 0.001) and rhinoconjunctivitis (20%, 95% CI 5% to 36%; p = 0.009). Conclusions: Although there was no objective evidence of benefit, symptoms of asthma and rhinitis improved and medication use declined following removal of indoor mould. It is unlikely that this was entirely a placebo effect.