Validating a new international cholesteatoma classification – a necessary but challenging task
Reviewed by Aileen Lambert

A European and Japanese joint consensus statement was published in 2017 which proposed a new cholesteatoma staging classification (EJS), with four stages. This follow-up publication aims to assess the internal and external validity of the staging system using existing prospectively collected data, from nine centres internationally, which held appropriate datasets. The parameters required for staging include site of origin of cholesteatoma, tympanomastoid subsites involved, recurrent versus residual disease, type of surgery, age of patient, and length of follow-up. The data used for validation purposes was collated from 1482 cases of primary cholesteatoma surgery. The largest group had Stage 2 (66%), followed by 22% with Stage 1. Stage 3 accounted for 11% and only 0.3% had Stage 4 disease. Interrater reliability of staging against the new EJS classification (between surgeon at each centre and the primary author) had a Kappa correlation score of 0.82. External validity (the ability of the staging system to have prognostic value for residual or recurrent disease) was determined using Kaplan-Meier curves of residual disease detection at five years: 50% in Stage 4, 13% in Stage 3 and 10% in Stage 2. Recurrent disease was low in all but Stage 4 (25%). The lack of correlation between stage and recidivism was proposed as being related to uncontrolled codependent variables (surgery type, patient age etc). The authors have used the limitations of applying old data to a new staging system to highlight the advantage of collecting data using one agreed staging system internationally (i.e. this new EJS staging system) which will allow future comparisons to be made across multiple sites looking at cholesteatoma outcomes. In particular, this study has identified important issues with variability in interpretation and staging which they argue could be reduced by improved clarification in terminology (e.g. using a broader definition of the S2 anatomic subsite which incorporates all the retrotympanic spaces medial to the facial nerve). There is an acknowledgement by the authors that the EJS may not yet be as refined as it needs to be but they appear to encourage its adoption now, at this early stage in its inception, so that databases can be designed to collect the data correctly in a prospective manner, which can then be used to modify the staging system as required to improve its utility.

International Collaborative Assessment of the Validity of the EAONO-JOS Cholesteatoma Staging System.
James AL, Tono T , Cohen MS, et al.
OTOLOGY AND NEUROTOLOGY
2019;40(5):630-7.