Research Techniques Made Simple: Itch Measurement in Clinical Trials.

Chronic itch, defined as itch lasting longer than 6 weeks, is a highly prevalent and debilitating symptom known to profoundly and negatively affect quality of life. The development of effective targeted therapies for some chronic itch disorders such as atopic dermatitis has given widespread recognition to the importance of measuring itch in clinical trials. Clinical trials now use itch measurement as a primary outcome measure, and steps toward the standardization of itch assessment are being made to meet the growing need for reliably measuring itch and its impact on quality of life in the clinical research setting. Itch can be evaluated via subjective patient-reported assessments or by objective measurement of scratching activity and scratching-induced skin changes. Herein, methods for the subjective assessment of itch via both unidimensional and multidimensional tools are discussed.