to the editor: We were surprised to see such a heavy emphasis placed on dust mite control in the article, “Environmental Control of Allergic Diseases.”1 Two Cochrane reviews2,3 conclude that the evidence for a clinically significant benefit of dust mite control efforts (e.g., fewer reduced activity days or days lost from school, rather than small changes in spirometric parameters) is, at best, limited. Given the substantial expense and effort involved in dust mite reduction efforts (many studies have provided fresh linens and house cleanings for participants because many people simply will not stick with such intensive regimens on their own), routinely recommending dust mite control can hardly be considered “benign.” Efforts to control asthma would be better spent increasing the use of anti-inflammatory medications by the substantial numbers of patients with persistent asthma who are not currently using controller medications.

In reply: We appreciate the comments of Drs. Saver and Doescher. While it is certainly true that anti-inflammatory medications have been shown to help patients with asthma, our article1 focused on the effects of environmental control measures on allergic disease, and we did not intend to compare these measures with other treatments. The Cochrane reviews2,3 concluded that more studies are needed to determine the benefit of environment control on asthma and allergic rhinitis symptoms. A large trial is currently under way for asthma. The data for allergic rhinitis are limited, but the Cochrane review included one study that showed that simple interventions, such as using mattress covers and washing bedding every two weeks to control dust mite exposure, may be beneficial. We believe that using dust mite covers on mattresses and pillows as well as washing bedding every one to two weeks are reasonable, inexpensive measures that should be recommended to patients with asthma until better data are available for guidance.