Measuring the prevalence of chronic itch in the general population: development and validation of a questionnaire for use in large-scale studies.

Itching is the most frequent symptom in dermatology. Little is known about its occurrence and its characteristics in the general population. Instruments specifically designed to measure itch are scarce. The aim of this pilot study was to develop and validate an instrument measuring prevalence and characteristics of chronic itch in the general population. A questionnaire was developed and administered to a sample from the general population (n = 200) and a sample (n = 100) of itch-clinic patients. Life time prevalence of itch was 22.6% in non-patients and 100% in patients. Principal component, internal consist ency and correlational analyses revealed the instrument to be able to reliably and validly measure itch. Strength of itch was higher in patients and was associated with itch- related quality of life and affect in both groups. Preliminary results indicate that itch is prevalent in the general population. We intend to utilize this parsimonious and easy-to-administer questionnaire in a forthcoming population-based study.