HOUSE-DUST MITE AVOIDANCE MEASURES IMPROVE PEAK FLOW AND SYMPTOMS IN PATIENTS WITH ALLERGY BUT WITHOUT ASTHMA - A POSSIBLE DELAY IN THE MANIFESTATION OF CLINICAL ASTHMA

Background: Asthma caused by allergy to house dust mite is a growing p roblem. Patients,vith allergy who do not have asthma (yet) might devel op asthma depending on exposure to precipitating factors. Objective: W e sought to determine whether house dust mite avoidance measures have an effect on the development of asthma. Methods: Patients with allergy (n = 29) who had no diagnosis of asthma (FEV1 of 99.1% +/- 10.6% of p redicted, peak how variability of 5.21% +/- 3.41%, reversibility of FE V1 after 400 mu g salbutamol of 3.92% +/- 3.73% according to the refer ence values) were randomly allocated (subjects blinded) to a treatment (n = 16) and a placebo group (n = 13). House dust mite avoidance trea tment consisted of applying Acarosan (Allergopharma, J. Ganzer KG, Ham burg, Germany) (the placebo group used water) to the boors (living roo m, bedroom), and the use of covers for mattresses and bedding that wer e impermeable to house dust mite (the placebo group used cotton covers for mattresses only). We tested whether the intervention had an effec t on peak flow parameters and asthma symptom scores during 6 weeks of treatment. Results: Significant improvements were seen in the treatmen t group in symptom scores (Borg score) for disturbed sleep, breathless ness, wheeze, and overall symptom score. Slight but statistically sign ificant improvements in peak how (morning, evening, and variability) w ere seen in the treatment group also. No significant changes were seen in the placebo group. Conclusions: Although this study is not long en ough to study the development of asthma, the results indicates that ho use dust mite avoidance measures had an effect on peak how parameters and asthma symptoms in patients with allergy but without asthma. These findings might implicate that a shift in developing clinically manife st asthma could be achieved with house dust mite avoidance measures. T o give a better answer to whether preventing the development of asthma is possible, larger studies with a longer follow-up period are necess ary.