Development and psychometric evaluation of a new itch assessment questionnaire for use in multi-ethnic Asian population

PURPOSE: The study aimed to develop and evaluate an itch assessment questionnaire (IAQ) to determine and monitor itch severity and its impact on quality of life (QOL) in a multi-ethnic Asian population. It addresses limitations of existing tools, which assess only narrow aspects of itch and require multiple instruments for a comprehensive evaluation of itch and its impact on patients' QOL. No single, validated multidimensional questionnaire currently reflects the cultural and ethnic diversity of Asian populations. METHODS: An exploratory, sequential, mixed-methods study was conducted in two phases in a primary care setting in Singapore. Phase one used literature review, preliminary qualitative study findings, expert discussions and qualitative interviews with 13 patients and 10 primary care physicians to develop a draft IAQ. In phase two, 250 participants (with and without itch) completed the draft IAQ, 5-D pruritus scale, and Dermatology Life Quality Index (DLQI) over three points, 4-10 days apart. Data was analysed to assess IAQ's validity and reliability. RESULTS: The final IAQ comprised 10 questions across three parts: itch severity, impact on QOL, and itch management. The IAQ demonstrated a strong correlation with the 5-D pruritus scale (ρ = 0.67, p < 0.001) and DLQI (ρ = 0.77, p < 0.001). The overall intraclass correlation coefficient and Cronbach α were 0.93 (95% CI = 0.91 to 0.95) and 0.94 (95% CI = 0.93 - 0.95), respectively. CONCLUSIONS: IAQ demonstrated construct validity and excellent reliability, suggesting its suitability for assessing itch severity and impact on QOL in multi-ethnic Asian populations.