Canine Pruritus Visual Analog Scale: how does it capture owners' perception of their pet's itching level?

Abstract

Accurate measurement of pruritus severity is difficult in veterinary medicine. To determine how the changes in Pruritus Visual Analog Scale (PVAS) scores at follow-up visits agree with the owners' perceptions of improvement of their pet's pruritus. One hundred and ninety two pruritic dogs were included in the prospective study and 196 in the retrospective study. Owners were randomly assigned into five groups and PVAS scores were recorded during two consecutive visits. Group A: previous scores were shown before completing the PVAS; Group B: PVAS was completed then owners were shown previous scores and asked to repeat the PVAS; Group C: PVAS was completed as reported previously; Group D: PVAS and a 0-10 verbal scale (VS) were completed. Retrospectively, PVAS scores were analysed during at least three consecutive visits. The average percentage and kappa agreements were calculated for all groups. In addition, PVAS and VS scores were compared in Group D. The average percentage and kappa agreements were higher in groups A (96%; 0.81), B [before (80%; 0.54), after (82%; 0.59) previous score] and D (85%; 0.47). Group C (79%; 0.37) had the lowest agreement. PVAS and VS scores were not significantly different (P=0.56) in Group D. The average percentage and kappa agreements for the retrospective study were 50.8% and 0.25. The highest values (63%; 0.355) were noted at 30-60day visit intervals. Showing owners previous scores could improve how PVAS captures the owner's perception of their dog's itching level.