Verbalizing extremes of the visual analogue scale for pruritus: a consensus statement.

Itch (pruritus) is an unpleasant sensation that leads to the desire to scratch (1). Pruritus may compromise quality of life and sleep in affected individuals. Pruritus is similar to pain, in being a subjective symptom; assessment of its intensity is a key issue in evaluating severity and therapeutic outcome of patients with pruritic disorders of diverse origins (cutaneous, systemic, neuropathic, psychogenic) (2). Various types of rating scales have been used and validated in the study of clinical itch, including the visual analogue scale (VAS), numerical rating scale, verbal rating scale, and behavioural rating scale (2–4). Among these measurement tools, the VAS seems to be one of the most commonly used methods of assessing pruritus severity, as it provides an easy and rapid estimation of itch (3, 4). The VAS is a 10-cm long line, oriented horizontally or vertically, on which patients indicate the intensity of pruritus by marking the line at the point that corresponds to the severity of their pruritus, where the beginning of the scale refers to no pruritus (0 point) and the end of the scale to the most severe pruritus (10 points) (3, 4). On behalf of the International Forum for the Study of Itch (IFSI), we discussed methodological problems of the VAS in clinical settings. During our discussion we identified that it is necessary to clarify the verbal expression of the 10-point end, because it varies from study to study. It includes expressions such as " worst imaginable itch " , " the most severe pruritus they can imagine " , " most intense sensation imaginable " , " maximal itch " , " severe itching " and " unbearable pruritus " (3–8). In this report, we propose to consolidate the verbalization of extremes of VAS for " itch intensity " and " sleep disturbance (nocturnal itch) ". and HS) discussed possible core items for evaluating pruritus in clinical settings, including clinical trials, in Japan. Nine items were proposed and we evaluated the importance of each item by assigning a weight score (maximum points, 10) to each. The 2 highest-ranked items were " itch intensity " (score, 10 ± 0) and " sleep disturbance " (9.3 ± 0.8), followed by " maximum score of itch " (7.3 ± 2.6), " itch frequency " (6.1 ± 1.8), " itch duration " (6 ± 2), " number of itch sites " (4.3 ± 2.6), " quality of …