Assessing the dynamic changes in vitiligo: reliability and validity of the Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS).

BACKGROUND: The assessment of the individual evolution of vitiligo is important for therapeutic decision making in daily practice. A fast, simple and validated physician-reported score to assess clinical changes in depigmentation over time in separate parts (activity and improvement) is currently missing. OBJECTIVE: The main objective of the study was to develop and validate the Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS). METHODS: The Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS) were evaluated based on a photo set of 66 patients with two different time points. In the first (short) version, only the number of changing body regions was counted based on 15 predefined areas (VDAS15 and VDIS15 ), while in the second (extensive) version the degree of worsening or improvement from +4 to -4 for each body area was added for a more detailed assessment (VDAS60 and VDIS60 ). Content and construct validity were tested. In addition inter-, intrarater reliability and feasibility were evaluated by 7 (test) and 5 (retest) physicians. RESULTS: Evidence for content and construct validity was provided. Overall, VDAS15 , VDIS15 , VDAS60 and VDIS60 demonstrated good to excellent inter-rater reliability [intraclass correlation (ICC): VDAS: range = 0.797-0.900; VDIS: range = 0.726-0.798]. The intrarater reliability ICCs were 0.865 and 0.781 for the VDAS15 and VDIS15 , respectively. Similar results were obtained for the VDAS60 and VDIS60 (ICC = 0.913 and 0.800, respectively). Completion time was short (median: 122 s/patient (first round); 95 s/patient (second round)]. LIMITATIONS: Single tertiary centre mainly of skin phototype 2 to 3. CONCLUSION: The VDAS and VDIS appear to be valid, reliable and feasible instruments to score the evolution of vitiligo lesions. This accommodates the current urgent need for a simple, standardized and practical assessment of vitiligo activity and improvement over time.

Reference method for digital surface measurement of target lesions in vitiligo: a comparative analysis.

BACKGROUND: Objective measurement of target lesions in vitiligo is important for clinical practice and trials, yet no preferred tool has been defined. Reported digital tools have shortcomings related to feasibility aspects and often lack information on validity, reliability and responsiveness. Moreover, studies are not yet based on ultraviolet (UV) photography. OBJECTIVES: To assess the reliability, validity and feasibility of two functions in ImageJ for measurement of target lesions, based on three different types of images including UV pictures. METHODS: Planimetric measurements were performed on photographs with and without UV, and lesion contours on transparent sheets of 52 vitiligo lesions from 10 patients with vitiligo. The ImageJ functions 'wand' and 'threshold' were used by three and four assessors, respectively. Inter- and intrarater reliability, hypothesis testing for construct validity, and feasibility were evaluated. RESULTS: The inter- and intrarater reliability for the 'wand' and 'threshold' functions were excellent [intraclass correlation coefficient (ICC) > 0·9] for measurement on pictures (with or without UV). The highest agreement (ICC > 0·95) and lowest variance were obtained for measurements on transparent sheets. All four hypotheses for construct validity were confirmed for all measurements. Overall, all measurement methods scored satisfactorily for user-friendliness. However, measurements on transparent sheets were preferred and the completion time was significantly faster. CONCLUSIONS: This study confirmed the reliability, validity and feasibility of two functions in ImageJ to measure target lesions in vitiligo. Based on the feasibility and included three-dimensional aspects, transparent sheets measured with the ImageJ 'wand' function can be proposed for future trials as a reference method to investigate the criterion validity of other digital instruments.