A DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL OF SOLIDIFIED BENZYL BENZOATE APPLIED IN DWELLINGS OF ASTHMATIC-PATIENTS SENSITIVE TO MITES - CLINICAL EFFICACY AND EFFECT ON MITE ALLERGENS

Background: The aim of this double-blind, randomized study was to investigate the effectiveness of an acaricidal cleaning product in modifying both clinical symptoms and mite allergen levels over a period of at least 1 year. Methods: Twenty-six asthmatic patients with proven Dermatophagoides pteronyssinus (Dp) asthma were selected; three were withdrawn from the trial. The patients' homes were divided into two groups; 11 homes were treated with solidified benzyl benzoate and tenside agents (A), and 12 were treated with a placebo (P). Two applications were performed at the beginning of the trial and at least 6 months later. Patients were examined 1 month before the trial, at the beginning of the trial, and every 3 months over a period of 1 year. Indoor mite exposure was evaluated by three methods: semiquantitative guanine determinations, quantitative guanine determinations, and the measurement of Der p I + Der f I (antigen P, of Dp + antigen F1 of D. farinae) levels. Results: The symptom scores established at the beginning of the trial and 12 months later showed a statistically significant improvement only in the A group (p < 0.01). The visual analog scale also showed a statistically significant difference both in the A (p < 0.05) and P groups (p < 0.01). No statistical differences were found between medication scores in the A or P groups. A statistically significant increase was also observed for forced expiratory volume in 1 second and maximal expiratory flow rate 25 / 75 in the two groups (p < 0.05 for P group; p < 0.01 for A group). The mean decreases in Der p I + Der f I in patient mattresses between the beginning of the trial and after 12 months were 20% for the acaricide group and 17% for the placebo group, respectively (NS). For house dust samples with origins other than the patients' mattresses we found significant decreases in Der p I + Der f I in the A group (p < 0.01 for carpets and p < 0.05 for upholstery elements).