Vol.:(0123456789) 1 3 Eur Arch Otorhinolaryngol (2017) 274:4277–4278 DOI 10.1007/s00405-017-4705-6 LETTER TO THE EDITOR The comparability of drug‑induced sedation endoscopy classifcation systems Esuabom Dijemeni 1,3  · Gabriele D’Amone 2,3   Received: 1 August 2017 / Accepted: 5 August 2017 / Published online: 28 August 2017 © Springer-Verlag GmbH Germany 2017 First, ‘Does using obstruction structures as compared to obstruction levels refect better DISE obstruction pattern?’ According to the European position paper [4], a DISE clas- sifcation system should represent obstruction patterns in terms of obstruction structures and/or obstruction levels. The site of obstruction used in NOHL tends towards obstruc- tion level: oropharynx and hypopharynx as compared to VOTE which tends towards obstruction structures: velum, oropharynx lateral walls, tongue base, and epiglottis. As concluded by da Cunha Viana Jr et al. in deduction 1 and 2, one can hypothesize that DISE classifcation systems based on uniquely identifable anatomical structures will provide a more anatomically precised analysis and potentially refect a better relationship with OSA severity and frequency of obstruction assuming the grading scale used to classify the severity and confguration of obstruction are relatively similar. Second, ‘Is reported DISE fndings biased towards the DISE classifcation system used?’ In terms of reporting DISE fndings, it is desirable that the obstruction observed in a DISE report contains accurate description of the observed obstruction patterns irrespective of the DISE classifcation system used. However, it is hypothetically unlikely that NOHL, VOTE or any other DISE classifcation system [5] used for reporting DISE fndings will describe a given DISE assessment in a way that the description of the fndings is not biased towards the properties of the DISE classifca- tion system used. The bias attributed to the properties of the classifcation system used will potentially propagate into surgical decision choices, treatment plans, and ultimately treatment outcomes. Third, ‘How can DISE classifcation systems be standard- ised?’ In this study, two widely used classifcation system were examined. Given that there are over 16 DISE classi- fcations [5], it will be interesting to know how diferent Dear Editor, We read with great interest the article ‘Drug-induced sleep endoscopy in the obstructive sleep apnea: comparison between NOHL and VOTE classifcations’ by da Cunha Viana Jr et al. [1]. We will like to start by commending the authors for conducting a comparative research on two of the widely used DISE classifcation systems, VOTE clas- sifcation system [2] and NOHL classifcation system [3]. There are three key points deducted from this research. First, the relationship between OSA severity and number of obstruction sites were signifcant for VOTE classifca- tion as compared to NOHL classifcation [1] (deduction 1). Second, VOTE classifcation system is a more comprehen- sive classifcation system in the analysis of the epiglottis and pharynx obstruction during DISE as compared to NOHL classifcation system (deduction 2). Third, the use of bispec- tral (BIS) index associated with DISE is a reliable tool for the assessment of OSA patients (deduction 3). Our interest in this paper lies in the comparability, relatability, and stand- ardisation of DISE classifcation systems. This letter focuses on three key discussion questions. This comment refers to the article available at doi:10.1007/ s00405-016-4081-7. * Esuabom Dijemeni e.dijemeni@imperial.ac.uk 1 Department of Bioengineering, Imperial College London, London, UK 2 Dyson School of Design Engineering, Imperial College London, London, UK 3 DISE INNOVATION, TechHub London, 20 Ropemaker St, London EC2Y 9AR, UK