A Cochrane review [Abstract] 1 included 9 trials with a total of 501 subjects. Only two studies investigating the effectiveness of mite impermeable bedding covers were of good quality; all other studies were small and of poor quality. Two trials investigated the efficacy of acaricides, another two trials investigated the role of high-efficiency particulate air (HEPA) filters. One trial, using a factorial design, investigated the efficacy of both acaricide and house dust mite impermeable bedding covers in isolation and combination; the remaining four trials investigated the efficacy of bedroom environmental control programmes involving use of house dust mite impermeable bedding covers. Seven of the nine trials showed that the investigated interventions result in significant reductions in house dust mite load when compared with control. Of the interventions studied to date, acaricides appear to be the most promising type of intervention, although the findings from these studies need to be interpreted with care because of their methodological limitations. Use of house dust mite impermeable bedding as an isolated intervention is unlikely to offer clinical benefit. No serious adverse effects were reported from any of the interventions.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment) and by imprecise results (limited study size for each comparison).
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