This evidence- and consensus-based guideline was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. The conference was held on 1 December 2016. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the EU-founded network of excellence, the Global Allergy and Asthma European Network (GA²LEN), the European Dermatology Forum (EDF) and the World Allergy Organization (WAO) with the participation of 48 delegates of 42 national and international societies. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell-driven disease, presenting with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous urticaria and other chronic forms of urticaria are disabling, impair quality of life and affect performance at work and school. This guideline covers the definition and classification of urticaria, taking into account the recent progress in identifying its causes, eliciting factors and pathomechanisms. In addition, it outlines evidence-based diagnostic and therapeutic approaches for the different subtypes of urticaria.

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Corporate partners of the EDF have been asked to contribute towards this work. GlaxoSmithKline plc. (GSK) and Meda AB have contributed funding for the development of the European evidence-based (S3) guideline for the treatment of acne (update 2016) through an educational grant to the EDF. Sponsors had no influence on the content of the guideline. Support was given independent of any influence on methods or results. Sponsors did not receive any information about methods, group members or likely results. The sources of the funding were not known to the experts of the guideline and were not disclosed before the finalization of the guideline. This is a short summary of the complete version of the S3 European Acne guideline, please see online appendix for full text (Document S1. Long Version) and detailed methods report (DOI: 10.1111/jdv.13783). Expiry date: 31 December 2020 MethodsIn order to weight the different recommendations, the group assigned a 'strength of recommendation'. It considered all aspects of the treatment decision, such as efficacy, safety, patient preference and the reliability of the existing body of evidence. Strength of recommendationIn order to grade the recommendation a "standardized guideline" language was used:

International guidelines are intended to be adapted to national or regional circumstances (regulatory approval, availability and reimbursement of treatments).

Knowledge about the development of untreated actinic keratosis (AK) and risk of progression into squamous cell carcinoma (SCC) is important. Therefore, we set out to synthesize primary data on the natural history of AK. We carried out a systematic literature search (Medline, Medline in Process, Embase, Cochrane) of studies on the natural course of AK, regarding (i) progression and regression rates per lesion-year, (ii) changes in total lesion counts over time, and (iii) spontaneous field regression and recurrence rates, taking into account studies on participants without immunosuppression and history of skin cancer, immunosuppressed patients and participants with a history of skin cancer and sunscreen use. Twenty-four eligible studies were identified providing data on at least one of the outcomes. Progression rates of AK to SCC ranged from 0% to 0·075% per lesion-year, with a risk of up to 0·53% per lesion in patients with prior history of nonmelanoma skin cancer. Rates of regression of single lesions ranged between 15% and 63% after 1 year. The data available on recurrence rates of single lesions 1 year after regression indicate a recurrence rate of 15-53%. Data on the relative change of total AK count over time are heterogeneous, and range from -53% to +99·1%. Spontaneous complete field regression rates range from 0% to 21%, with recurrences in 57%. In general, the available data are limited. Important methodological limitations apply. Currently, no reliable estimates concerning the frequency of AK developing into invasive carcinoma can be given, and further studies are needed.