The validity, reliability and acceptability of the SAVASI; a new self-assessment score in vitiligo

Background Vitiligo is a common depigmenting skin disorder that can influence a patient's quality of life. Although patient‐orientated medicine is an emerging concept, a self‐assessment tool to assess the degree of depigmentation in vitiligo is not yet available. Therefore, we developed the SAVASI, a self‐assessment tool that uses the same basic principles as the VASI. Objective To assess the validity, reliability and acceptability of the SAVASI. Methods To assess the validity of the SAVASI, we compared the scores assessed by the patient with the scores of the VASI assessed by the physician. To assess the intra‐rater reliability, the correlation between the baseline SAVASI and the SAVASI after 2 weeks was calculated. To assess the acceptability, patients indicated the time needed to complete the SAVASI and the patient assessed the difficulty of the questionnaire on a five‐point scale. The Skindex‐29 was used to determine the quality of life. The overestimation of the SAVASI compared to the VASI was calculated by subtracting the VASI scores off from the SAVASI scores. Results A high correlation between the VASI and the SAVASI (ICC 0.97, 95% CI: 0.95–0.98) was found in 60 patients. The intra‐rater reliability of the SAVASI (ICC 0.75, 95% CI 0.54–0.87) was adequate in 31 patients. Fifty (83%) of the patients completed the questionnaire within 10 min and only five (8%) of the patients considered the SAVASI hard. We found no correlation between overestimation of the SAVASI score and the Skindex‐29 score. Conclusion The SAVASI is a valid, reliable and acceptable self‐assessment tool to measure the degree of depigmentation in vitiligo. With the SAVASI the degree of depigmentation can reliably be assessed by the patient themselves which can be useful in large (epidemiological) studies. Furthermore, this could contribute to the patient's disease insight and therapy loyalty.