BackgroundThe Self Assessment Vitiligo Extent Score (SA‐VES) is a validated, patient‐reported outcome measure to assess the body surface area affected with vitiligo. Information on how to translate the obtained score into extent, severity and impact strata (mild–moderate–severe) is still lacking. Stratification is helpful to define inclusion criteria for trials, enables comparison and pooling of trial results and can be used for epidemiological research.ObjectivesThe aim was to develop extent, severity and impact strata for the SA‐VES based on validated anchor‐based questions.MethodsIn total, 315 patients with vitiligo (non‐segmental; age ≥ 16) recruited at the Ghent University Hospital (Belgium) completed a questionnaire that was conducted in cooperation with the Dutch Society for vitiligo patients to ensure content validity. First three anchor questions included in the questionnaire [Patient Global Assessment (PtGA) for vitiligo extent, severity and impact] were assessed for content validity, construct validity and intrarater reliability. Subsequently, the PtGAs were used to stratify the SA‐VES based on ROC analysis.ResultsFor all PtGAs (PtGA extent, PtGA severity, PtGA impact), at least 75% of hypotheses evaluated for construct validity were confirmed. Intrarater reliability of all PtGAs was good to excellent (ICCs PtGA extent: 0.623; PtGA severity: 0.828; PtGA impact: 0.851). The optimal cut‐off values of the SA‐VES between the three global categories (mild/limited – moderate – severe/extensive) were 1.05% and 6.45% based on PtGA extent, 2.07% and 4.8% based on PtGA severity and 2% and 3.35% based on PtGA impact.ConclusionThis study provides the first guide for the interpretation of the numerical output obtained by the SA‐VES (vitiligo extent) and enables the translation into a global vitiligo grading for extent, severity and impact. As patients’ interpretation of vitiligo extent, severity and impact may vary amongst patients worldwide, future international studies will be required.

Abstract-High-dynamic-range (HDR) technology allows capturing of video content at a wider range of luminance than lowdynamic-range (LDR) video. The resulting video more closely resembles the scene as perceived by the human eye. However, displays currently support only a limited range of HDR. Therefore, both an HDR version and LDR version of a video should be encoded during content acquisition. This means that the cost of encoder hardware in cameras would double. As a solution, this paper proposes a multistream video encoder that allows generating an HDR and LDR version of the same HDR video footage at roughly the same computational complexity as a single encoder, effectively allowing encoding of two dynamicrange versions of the video with a negligible increase in cost. For the LDR version, this multistream encoder results in a bit rate overhead of only 11.6% for the same quality as a two-encoder solution.