The validity and reliability of the Thai-version of 5-D itch scale

Pruritus is commonly associated with skin disorders. The 5-D itch scale was developed as a specific questionnaire for pruritus.

This study aimed to evaluate the validity, reliability, and sensitivity to change of the Thai 5-D itch scale in Thai patients.

The Thai Dermatology Life Quality Index (DLQI), patient's global assessment of disease severity (PatGA-VAS), Chronic Urticaria Quality of Life Questionnaire (CU-Q2oL), and seven-day urticaria activity score (UAS7) were evaluated as correlation with Thai 5-D itch scale. Seventy-five stable patients (42 chronic urticaria patients and 33 eczema patients), who had no change in disease severity after 4-weeks were assessed for test-retest reliability.

Of 130 pruritus patients who were treated at Department of Dermatology, Siriraj Hospital, 65 patients were diagnosed with chronic urticaria. The others were diagnosed with eczema. The validity of Thai 5-D itch scale correlated strongly with Thai DLQI total score (r = 0.76, p < 0.0001) and PatGA-VAS (r = 0.79, p < 0.0001). The strong reliability of Thai 5-D itch scale was demonstrated as intraclass correlation coefficient of 0.90. The changes in Thai 5-D itch scale was correlated with the changes in PatGA-VAS and UAS7 which indicated that the Thai 5-D itch scale had good sensitivity to change (r = 0.66) and (r = 0.67), respectively.

The Thai 5-D itch scale is a questionnaire with good validity, reliability and sensitivity to change to evaluate pruritus in Thai patients. This will support the use of 5-D itch scale in practice, in other languages.