Validation of a Patient Global Assessment for extent, severity and impact to define the severity strata for the Self Assessment Vitiligo Extent Score (SA-VES).

BACKGROUND: The 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. OBJECTIVES: The aim was to develop extent, severity and impact strata for the SA-VES based on validated anchor-based questions. METHODS: In 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. RESULTS: For 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. CONCLUSION: This 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.

Understanding transportation-caused rangeland damage in Mongolia.

Mongolia, a vast and sparsely populated semi-arid country, has very little formal road infrastructure. Since the 1990s, private ownership and usage of vehicles has been increasing, which has created a web of dirt track corridors due to the communal land tenure and unobstructed terrain, with some of these corridors reaching over 4 km in width. This practice aids wind- and water-aided erosion and desertification, causing enormous negative environmental effects. Little is being done to counter the phenomenon, mainly because the logic of the driving behaviour that causes this dirt road widening is not fully understood. The research in this article postulates that this driving behaviour has rational foundations and is linked to various geographical factors (natural and man-made geographical features). We analysed 11,000 km of arterial routes in the country using spatial statistics and determined that geographically weighted regression (GWR) analysis offers a good explanation for whether, and by how much, the selected geographical factors affect the creation of corridor widths and how their effect varies across the landscape. We determined that corridor widths are correlated to factors such as proximity to river crossings, traffic intensity, and vegetation abundance. Knowing these factors can help local planners and engineers design counter-measures that could help to control and reduce the widths of these corridors, until paved roads can replace the dirt track corridors.

Standardization of measuring power output during wheelchair propulsion on a treadmill Pitfalls in a multi-center study.

OBJECTIVE: In a multi-center study the power output of wheelchair propulsion, attained by a wheelchair drag test, differed among rehabilitation centers. The purpose of this study was to investigate what causes the differences in drag force among centers. METHODS: A set of standardized drag tests was performed while systematically varying the calibration set of the force transducer, the tester and the wheelchair. In addition, the actual calibrated velocity and slope of the treadmill were measured. RESULTS: Difference in drag force among centers was due to variation in wheelchair set-up and differences in the slopes between treadmills. The drag force was not significantly different when different testers performed the test. The belt velocity in almost all centers was lower than the manufacturer specified (assumed) velocity. CONCLUSION: The drag test appeared a robust test as far as the tester is considered. Variation in wheelchairs and differences in the actual slopes of the treadmills affected the imposed drag force. The assumed velocity of the treadmill led to an overestimation of the power output. The power output in the multi-center study should be recalculated using the measured velocities and the wheelchair set-up should be more standardized.