Prevention of allergic sensitization by environmental control.

For about 20 years, investigators have been attempting to design studies to reduce exposure to allergens in order to prevent the development of allergic sensitization and thus prevent the onset of allergic disease, particularly asthma. Seven such studies-environmental control studies-have attempted to accomplish this by changing the domestic environment into which a high-risk child is born. Some of these studies also included a dietary intervention aimed at reducing the risk of development of sensitization to food allergens. In this review, we summarize the seven studies, compare study designs, and evaluate the effectiveness of the environmental control measures adopted. We present published results, focusing on the most recent. There is great heterogeneity of results that cannot be explained by the variety of study designs alone. We propose that the next generation of primary prevention studies will be informed by epidemiologic studies of gene-environment interactions and will investigate the effects of tailor-made measures targeting individuals with specific susceptibilities who may benefit from specified interventions.