Systematic review and evidence-based consensus guideline on prevention of allergy and atopic eczema of the German Network on Allergy Prevention (ABAP).

Allergies are a meaningful public-health problem. Until now no evidence-based recommendations for allergy prevention exist. An evidence based guideline for primary and secondary prevention of allergies was developed in the course of the German Network on Allergy Prevention (Aktionsbündnis Allergiepräven-tion, ABAP) with support of the German Ministry of Health. Results of the systematic evidence search and the consented recommendations are presented here. After an appropriate search strategy was developed, a systematic literature search was performed in electronic databases (Cochrane library, MEDLINE, EMBASE). Furthermore four selected journals were hand-searched and reference lists of actual reviews as well as grey literature was screened. Some 3 500 references were retrieved initially and a two-stage filter process on the relevance was applied by screening titles and abstracts and subsequently full-text papers. For the critical methodological appraisal modifications of international checklists were used. A total of 323 studies were included and evaluated. These comprised 3 Cochrane Reviews, 7 meta-analyses, 37 randomized controlled trials (RCTs) as well as 102 cohort and 174 case-control-studies. The following levels of evidence were applied: 3x1a, 21x1b, 5x2a, 59x2b, 1x3a, 45x3b, 189x4. These studies were summarized in a form of a systematic review and corresponding recommendations were formulated. The latter were consented by members of the abap steering committee in two consensus meeting where the method of a nominal group process was applied. For the first time recommendations for the prevention of allergies were developed on a high methodological standard. The content and modifications reflect the existing evidence.