Environmental interventions for mite-induced asthma: a journey between systematic reviews, contrasting evidence and clinical practice.

House dust mites (HDM) are one of the most important sources of indoor allergens worldwide. Exposure to high environmental levels of dust mite allergen is associated with an increased risk of sensitization, asthma and deterioration of lung function. On the basis of these data, it would be logical to assume that asthmatic patients with mite allergy could benefit from a reduction of exposure to these allergens. Several environmental prophylactic actions against HDM, either physical or chemical have been tried, alone or in different combinations. However, a recent Cochrane Systematic Review did not detect specific clinical benefits from the use of prophylactic environmental measures in asthmatic patients sensitive to HDM and concluded that such measures can no longer be recommended as they are ineffective. This paper presents the results of a web-based questionnaire, administered to more than 200 Italian paediatricians, and shows that physicians' behaviour in real life is very far from SR conclusions. It also summarizes the indications of the most authoritative guidelines, highlighting some contrasting evidence and some significant weaknesses of the SR, that could make the final conclusions at least uncertain. In the light of these findings, it seems that the recent Cochrane SR cannot be considered the definitive document on the uselessness of environmental prevention of mite-related asthma.