Assessment of pruritus in patients with psoriasis and atopic dermatitis: subjective and objective tools.

Pruritus is a major symptom of skin disease. The quest to identify a valid and reliable method to assess this important symptom has led to the development of a myriad of measurement tools. Some clinical trials using subjective measurements of itch intensity have reported itch intensity levels in psoriasis that are close to severity levels found in atopic dermatitis. Although it is possible that we have previously underestimated the severity of pruritus in psoriasis, these unexpected findings prompted us to review and evaluate these subjective methodologies. We provide an overview of the current tools available to measure itch severity, including subjective rating scales and questionnaires and objective measures of scratch activity through videotape observation and wrist actigraphy. We discuss the advantages and limitations of these methods and encourage consideration of a novel objective method of evaluation.