House dust mite avoidance measures for perennial allergic rhinitis: an updated Cochrane systematic review

Background: To assess the benefits and harms of measures designed to reduce house dust mite (HDM) exposure in the management of house dust mitesensitive allergic rhinitis. Methods: Systematic review of randomized controlled trials was made, in which HDM control measures have been evaluated in comparison with placebo or other HDM avoidance measures, in patients with clinically proven allergic rhinitis. Results: Nine trials involving 501 participants satisfied the inclusion criteria. These trials have investigated the effectiveness of bedroom environmental control programmes involving the use of HDM impermeable bedding covers (n = 4), acaricides (n = 2), high-efficiency particulate air filters (n = 2) and, using a factorial design, acaricide and HDM impermeable bedding covers in isolation and combination (n = 1). Seven of the nine trials reported that, when compared with control, the interventions studied resulted in significant reductions in HDM load. Of the interventions studied to date, acaricides appear to be the most promising, although the findings from these studies need to be interpreted with care because of their methodological limitations. House dust mite impermeable bedding as an isolated intervention is unlikely to offer benefit. Conclusions: Trials have tended to be small and of poor methodological quality, making it difficult to offer any definitive recommendations. Interventions that achieve substantial reductions in HDM load may offer some benefit in reducing rhinitis symptoms. Isolated use of HDM impermeable bedding is unlikely to prove effective