Clinically significant differences in patient-reported outcomes evaluations in chronic spontaneous urticaria

The aim of this review is to highlight the conceptual and practical knowledge for interpreting score changes in patient-reported outcomes (PROs) that have been validated for chronic spontaneous urticaria (CSU).

The urticaria guidelines recommends to assess PROs as Health-Related Quality of Life, disease activity and disease control, to detect the CSU impact and the overall treatment effect. To this aim it is crucial to determine the minimal important difference (MID) to assess if changes in questionnaire scores represent either perceived improvement or deterioration for patients. Methods for establishing the MID are well defined and are clustered into two broad categories: distribution-based and anchor-based.

For the majority of the available questionnaires for CSU, an MID has been defined, according to the results of various approaches. In most of the studies in our review, anchor-based methods, either alone or in combination with distribution ones, were used. The available information regarding MIDs across validated tools for CSU patients helps to interpret measurement scores and allows the implementation of PROs in routine practices.