RESEARCH ARTICLE Open Access Estimated cut-off values for pemphigus severity classification according to pemphigus disease area index (PDAI), autoimmune bullous skin disorder intensity score (ABSIS), and anti-desmoglein 1 autoantibodies Farnam Mohebi 1,2† , Soheil Tavakolpour 1† , Amir Teimourpour 3† , Roja Toosi 1† , Hamidreza Mahmoudi 1 , Kamran Balighi 1 , Narges Ghandi 1 , Maryam Ghiasi 1 , Pedram Nourmohammadpour 1 , Vahideh Lajevardi 1 , Robabeh Abedini 1 , Armaghan Azizpour 1 , Maryam Nasimi 1 and Maryam Daneshpazhooh 1* Abstract Background: Pemphigus is a potentially fatal disease if left untreated. Valid scoring systems and defined cut-off values for classification of patients would help with better management through specified pharmaceutical and non- pharmaceutical treatments. Methods: In this study, pemphigus patients who were receiving immunosuppressive treatments and had recent disease relapse were recruited for examination of pemphigus disease area index(PDAI), autoimmune bullous skin disorder intensity score (ABSIS), physician global assessment (PGA), autoimmune bullous disease quality of life (ABQoL), anti-desmoglein 1 (anti-Dsg1), and anti-Dsg3 autoantibody titers from December-2017 to February-2018. Cut-off values were estimated using model-based clustering classification and the 25th and 75th percentiles approach, performed separately for the exclusive cutaneous, exclusive mucosal, and mucocutaneous groups. Results: In the 109 included patients, the 25th and 75th percentiles cut-offs were 6.2 and 27 for PDAI score, and 4 and 29.5 for ABSIS score. The model-based analysis resulted in two groups (cut-point:15) for PDAI score, and three groups (cut-points:6.4 and 31.5) for ABSIS score. The groups were significantly different for the PDAI, ABSIS, PGA, and ABQoL values. Based on anti-Dsg1 autoantibody values, the model-based analysis cut-point was 128 and the 25th and 75th percentiles cut-offs were 98 and 182. Anti-Dsg3 autoantibody values did not differentiate between pemphigus severity classes. (Continued on next page) © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. * Correspondence: maryamdanesh.pj@gmail.com † Farnam Mohebi, Soheil Tavakolpour, Amir Teimourpour and Roja Toosi contributed equally to this work. 1 Autoimmune Bullous Diseases Research Center, Tehran University of Medical Sciences, Razi Hospital, Vahdate-Eslami Square, Tehran 11996, Iran Full list of author information is available at the end of the article Mohebi et al. BMC Dermatology (2020) 20:13 https://doi.org/10.1186/s12895-020-00105-y