Development and Validation of a New Scoring Tool to Evaluate the Clinical Evolution of Adult Patients with Nonsegmental Vitiligo

Abstract

<b><i>Background:</i></b> Vitiligo has an unpredictable course and a variable response to treatment. Furthermore, the improvement of some vitiligo lesions cannot be considered a guarantee of a similar response to the other lesions. Instruments for patient-reported outcome measures (PROM) can be an alternative to measure complex constructions such as clinical evolution. <b><i>Objective:</i></b> The aim of this study was to validate a PROM that allows to measure the clinical evolution of patients with nonsegmental vitiligo in a simple but standardized way that serves to gather information for a better understanding of the disease. <b><i>Methods:</i></b> The instrument was created through expert consensus and patient participation. For the validation study, a prospective cohort design was performed. The body surface area affected was measured with the Vitiligo Extension Score (VES), the extension, the stage, and the spread by the evaluation of the Vitiligo European Task Force assessment (VETFa). Reliability was determined with test-retest, construct validity through hypothesis testing, discriminative capacity with extreme groups, and response capacity by comparing initial and final measurements. <b><i>Results:</i></b> Eighteen semi-structured interviews and 7 cognitive interviews were conducted, and 4 dermatologists were consulted. The instrument Clinical Evolution-Vitiligo (CV-6) was answered by 119 patients with a minimum of primary schooling. A wide range was observed in the affected body surface; incident and prevalent cases were included. The average time to answer the CV-6 was 3.08 ± 0.58 min. In the test-retest (<i>n</i> = 53), an intraclass correlation coefficient was obtained: 0.896 (95% CI 0.82–0.94; <i>p</i> < 0.001). In extreme groups, the mean score was 2 (2–3) and 5 (4–6); <i>p</i> < 0.001. The initial CV-6 score was different from the final one and the change was verified with VES and VETFa (<i>p</i> < 0.05, <i>n</i> = 92). <b><i>Conclusions:</i></b> The CV-6 instrument allows patient collaboration, it is simple and brief, and it makes it easier for the doctor to focus attention on injuries that present changes at the time of medical consultation.

Interpretación y evaluación de las propiedades de medición de los cuestionarios contestados por los pacientes

“…El objetivo consiste en demostrar una correlación directa o inversamente proporcional entre las puntuaciones obtenidas con el nuevo instrumento y las obtenidas con los criterios externos con base en conjeturas teóricas, de tal forma que esa relación sostenga una hipótesis creada a priori. 26 Por ejemplo, si el instrumento PRO pretende medir bienestar del paciente, sus puntuaciones serán divergentes con las puntuaciones de otro instrumento validado que mida gravedad de la enfermedad (mayor gravedad menor bienestar) y convergente con un instrumento validado que mida calidad de vida (a mayor calidad de vida mayor bienestar); por lo cual se denomina validez convergente o divergente. 25,27 Validez estructural.…”

“…29 Por último, los puntos obtenidos al aplicar el instrumento deben ser fácilmente interpretables; por ejemplo, www.medigraphic.org.mx el CV-6 es un instrumento para medir la evolución de los pacientes con vitíligo, a medida que se incrementa el número o tamaño de las lesiones se incrementa la puntuación; entonces, si hay incremento en el número o tamaño de las lesiones a través del tiempo, se puede entender que la enfermedad está empeorando y viceversa, si no hay cambio se considera estable. 26…”