Visual analogue scale: evaluation of the instrument for the assessment of pruritus

Abstract

The aim of this study was to evaluate the visual analogue scale (VAS) as a method of pruritus assessment. A total of 310 subjects with pruritic dermatoses (148 Caucasian subjects and 162 Asian subjects) were recruited. The patients assessed pruritus intensity using the horizontal and vertical VAS, numeric rating scale (NRS) and verbal rating scale (VRS). All scales showed very good reproducibility (intraclass coefficient (ICC) > 0.8). No significant differences were found between the horizontal and vertical VAS (5.3 ± 2.9 vs. 5.3 ± 3.0 points, p = 0.34). Using NRS, patients rated their pruritus significantly higher than with VAS (5.7 ± 2.6 points, p < 0.01). VRS showed the highest correlation with NRS (R = 0.82, p < 0.001), followed by horizontal (R = 0.75, p < 0.001) and vertical VAS (R=0.74, p < 0.001). Based on detailed analysis following VAS categories were proposed: 0 = no pruritus, > 0-< 4 points = mild pruritus, ≥ 4-< 7 points = moderate pruritus, ≥ 7-< 9 points = severe pruritus, and ≥ 9 points = very severe pruritus. In conclusion, the VAS is a valuable method of pruritus measurement.