Refinement and validation of the ItchyQoL using classical test theory and item response theory resulted in a reduction of the response categories from a 5-point to a 3-point scale.

We suggest a revision of the response categories of the ItchyQoL from a 5-point to a 3-point scale. When this revision was applied, the ItchyQoL showed excellent structural validity according to CTT and IRT/Rasch. The calculation of an overall ItchyQoL sum score is allowed.