Who will benefit from hyposensitization? Predictive parameters in house dust mite allergic asthmatics

The aim of this study was to assess the ability of various data collected before treatment to predict the therapeutic benefits of hyposensitization. Thirty-one asthmatics were hyposensitized with extract from the house dust mite Dermatophagoides pteronyssinus (Dp) for 2 years, 15 comparable patients served as controls. The treatment extract was either modified by coupling to monomethoxypolyethylene glycol (mPEG) or administered in a diluent containing Al(OH)3. Improvement would be either a greater than or equal to 10-fold increase in bronchial tolerance to Dp or an overall clinical effect judged from questionnaires plus diary cards. Patients improving in bronchial Dp-sensitivity after 1 year had been more sensitive to DP pre-treatment in bronchi and in basophils, and had a lower FEV1 compared with the patients not improving (P less than 0.05). Occurrence of late-phase bronchospasm to pre-treatment Dp-challenge increased the chance of clinical improvement approximately 3-fold (P less than 0.05). A certain mite exposure seems to be a condition of an improvement in symptoms/medication. In patients improving, the median allergen concentration on mattresses was equivalent to 1,000 mites/g compared with less than 250 mites/g in patients showing no clinical improvement (P = 0.1). Information on Dp-specific IgE, IgG, IgG subclasses, Dp-sensitivity in skin, nose and eyes, age, and duration of symptoms did not permit any prediction of therapeutic effect.