Prurigo Activity Score (PAS): validity and reliability of a new instrument to monitor chronic prurigo.

Pölking J; Zeidler C; Schedel F; Osada N; Augustin M; Metze D; Pereira MP; Yosipovitch G; Bernhard JD; Ständer S

Abstract

BACKGROUND - OBJECTIVE - METHODS - RESULTS - DISCUSSION; Currently available tools to monitor patients with chronic prurigo over time focus on pruritus and quality of life parameters, while no instrument objectively assessing the pruriginous lesions is yet available.; The objective of this study was to develop a physician-assessed Prurigo Activity Score (PAS), a new tool to monitor the distribution and activity of chronic prurigo lesions and to evaluate its reliability and validity.; The 7-item PAS questionnaire as well as validated pruritus intensity scales (VAS, NRS) and a skin-related quality of life score (DLQI) were completed for 264 patients (172 females, age 61 years) at least twice over a period of 2 years. In addition, a 60-min test-retest reliability test was performed by four experts for a random sample of 12 patients.; The PAS showed good test-retest reliability (Cohens κ > 0.61; Cronbach-alpha > 0.76), ordinal or metric items showed high inter-rater reliability (Kendalls > 0.61) and items recording the number of lesions correlated significantly to each other (P < 0.001). The highest correlation to external constructs was achieved with DLQI. The feasibility test conducted by four raters indicated the suitability of PAS for tracking chronic prurigo in the clinical setting.; The PAS is a useful tool to objectively monitor pruriginous lesions in chronic prurigo patients over time. The sensitivity of change in the PAS score should be analysed in future studies.