Children's rating of itch: an experimental study

Little is known about children's ability to assess itch. The present paper aimed to investigate the discriminative capacity of two itch rating scales in children. Sixty healthy children, 4 to 12 years of age, participated. Itch was provoked with three histamine concentrations (0.1, 1.0, and 10 mg/ml). Physiologic saline was the negative control. The test solutions were pricked with a lancet into the skin of the lower arms in random order under coded conditions. The overall itch intensity for each skin prick was rated with a 100-mm visual analog scale and a four-stepped verbal rating scale (none, mild, moderate, and severe itch). In addition, the itch duration and flare response were recorded. A significant dose-response relationship was shown for the itch duration and itch intensity as rated with both scales. This was also true for the flare response, indicating a correct skin prick technique. However, children 4 to 5 years of age rated the itch intensity (both scales) less well than those aged 6 to 12 years. The younger age group discriminated between saline and histamine, but not between the different histamine concentrations. In conclusion, children aged 6 to 12 years were able to discriminate between different itch stimulus strengths in a dose-dependent way with a 100-mm visual analog scale and a four-stepped verbal rating scale, indicating the validity of these scales for measurement of experimental itch in children 6 years or older.