The cost of an itch: A nationally representative retrospective cohort study of pruritus-associated health care expenditure in the United States

Pruritus, or itch, is a prevalent symptom causing profound health burden in many dermatological and non-dermatological disorders. Several itch questionnaires have been created to assess itch. Particularly, Eppendorf Itch Questionnaire (EIQ) is widely accepted since it encompasses various aspects of itch, including intensity, affects, coping behavior, and motivation to scratch.In a cross-sectional survey, we examined the validity, reliability and clinical utility of Traditional Chinese EIQ.We administered the consensus version to 128 adults (median: 48.5 years, interquartile range [IQR]: 39–63) with active itch for more than 6 weeks at the Outpatient Clinics of three medical centers in Taiwan. Clinical diagnoses included psoriasis (N = 82), xerosis (N = 34), or other dermatitis (N = 12). Cronbach's alpha for each EIQ scale ranged 0.82–0.98, suggesting good to excellent internal consistency and reliability. Three EIQ scales significantly correlated with visual analogue scale (VAS) for itch intensity (P ≤ 0.001 for median test), supporting for its concurrent validity. None of EIQ scale was statistically correlated with Psoriasis Area Severity Index (PASI) scores in psoriasis patients, confirming its discriminant validity. Moreover, patients of different diagnoses had distinct responses to the multi-scale EIQ index, affording it a better clinical test (area-under-the-ROC curve [AUC]: 0.76, 95% CI: 0.63–0.90) than VAS alone (AUC: 0.42, 95%CI: 0.24–0.59) in distinguishing dermatitis/eczema-related itch from psoriasis or xerosis-related itch.We demonstrated the reliability and validity of Chinese EIQ in adult patients with chronic itch at the outpatient setting. The study also revealed the diversified aspects of itch across patients with various dermatoses.