ItchApp？: An App-based eDiary for Assessment of Chronic Pruritus in Clinical Trials

Performing a reliable assessment of chronic pruritus remains a challenge. Electronic diaries are often used, but many of the scales have not been validated. ItchApp？ was developed for Android smartphones in order to address this lack. A total of 40 subjects with chronic pruritus completed questionnaires both on paper and with ItchApp？ (verbal rating scale, numerical rating scale, dynamic pruritus score) in order to validate the software application. Strong correlations were found for test–retest reliability (intraclass correlation coefficient: 0.865–0.977) and convergent validity (Spearman’s r: 0.442–0.924). A feasibility questionnaire for ItchApp？ revealed a high level of user friendliness and compliance. This was confirmed in a randomized controlled trial with 68 subjects, for which the clinically important difference in the numerical rating scale values for ItchApp？ was calculated (2.61 points). In summary, ItchApp？ is a recently developed eDiary that can provide experts with a reliable evaluation of patients with chronic pruritus. It will be made available for future clinical trials.