A practical method for the estimation of vitiligo surface area: a comparison between the point counting and digital planimetry techniques

Abstract

The accurate measurement of vitiligo surface area is fundamental to the evaluation of treatment efficacy. Digital photography, planimetry and clinical evaluation by the clinician have been used for assessment. Although digital photography with computerized planimetry is a reliable and accurate method, it is labour intensive and expensive. The aim of this study was to evaluate the accuracy and reliability of the point counting method and to compare it with digital planimetry techniques for the estimation of vitiligo surface area. Surface areas of 31 vitiligo lesions of five volunteers were estimated using the point counting and digital planimetry methods. Three independent observers evaluated the outlined areas twice using the point counting technique with an interval of 2 weeks. The same lesions were also measured by one observer applying digital planimetry. The estimation results of three observers were compared using inter and intra-observer correlation analysis test. There was significant inter- and intra-observer agreement for all measurements. There was also significant coincidence between each observer's estimation of the point counting and digital planimetry method. No significant differences on the results of surface area obtained using the two methods were found (p > 0.05). The point counting method may be used as a direct and reliable technique to measure the vitiligo surface area.