Background: allergen-specific immunotherapy has proved to be effective in selected patients with IgE-mediated respiratory allergic diseases, and alternative routes of administration are being studied. Atopic Dermatitis (AD) is currently regarded as an allergic inflammatory disease.
Methods: we conducted a cohort study to evaluate the safety and effectiveness of sublingual-swallow immunotherapy (SLIT) in selected patients with allergic (extrinsic) AD. Thirty-five patients, 16 suffering from AD without respiratory allergic symptoms (Group A) and 19 with AD associated to mild asthma and/or rhinitis (Group B), were enrolled in the study. The severity of the skin lesions (eczema) was scored on a 0 to 4 scale (and subsequently related to the more recent SCORAD Index), where 0 indicated complete healing of the eczema and 4 indicated maximal spread of the lesions. Only patients with an eczema score of 1 to 3 were started on allergen-specific SLIT for 36 months. Eczema scores, symptoms and side effects were recorded every two months during the first 2 years and then after 36 months. After SLIT was completed, all patients attended 3 yearly follow-up visits to evaluate the long-term effects of the treatment. All patients followed a set of rules designed to control for identified confounding variables. All patients received ketotifen during the first 3 months of SLIT.
Results: only the complete disappearance of skin lesions (score 0) was considered to indicate effectiveness. In Group A this was observed in 12.6% of the patients after 6 months of SLIT, in 31,2% after 12 months and 68.8% after 24 months. In Group B, eczema disappeared in 0% after 6 months, in 36.8% after 12 months and 73.7% after 24 months. No patients in Group A developed asthma during SLIT, and 1 patient developed asthma 3 years after immunotherapy had ended. Three focal reactions consisting of 2 cases of mild eczema and one case of diarrhoea were recorded. One case of urticaria, due to violation of the administration schedule was the only systemic reaction observed. No life-threatening reactions appeared at any time of the study.
Conclusions: the outcomes obtained, taken into account the limitations of the study design, suggest that sublingual allergen-specific immunotherapy for the treatment of the extrinsic form of Atopic Dermatitis is safe and well tolerated by patients, and may favourably affect the natural course of the disease.