Development and initial validation of a traditional Chinese medicine symptom-specific outcome measure: a Zheng-related atopic dermatitis symptom questionnaire (ZRADSQ)

Background: Zheng represents pattern differentiation in Traditional Chinese Medicine (TCM), as the basic unit and a key concept in TCM therapeutic theory, is based on the physiology and pathology of TCM. None of the outcome measurements of atopic dermatitis (AD) are Zheng-specific. The effectiveness of TCM is likely to be underestimated without a Zheng-related symptom-specific instrument. The aim of this study was to develop an instrument for measuring the Zheng-related symptom-specific status of patients with AD. Methods: We followed standard methodology to develop the instrument, including item generation and selection, item reduction and presentation, and pretesting, and recruited 188 patients with AD involved in a six-center randomized-controlled trial (ChiCTR-TRC-08000156) to validate the questionnaire. We conducted construct validity, reliability, and responsiveness analysis. The standardized effect size (SES) and standardized response mean (SRM) were used to calculate the responsiveness of additional items and the total score for the rating items. Results: ZRADSQ has 15 items, with 12 rating items and 3 additional items. The 12 rating items fall within three domains: AD symptoms (n = 6 items); Heat (n = 4 items) and Mood (n = 2 items). Confirmatory factor analysis provided good support for a three-factor model (d.f. = 51, x(2)=97.11, RMSEA = 0.07, CFI = 0.96), and the Pearson's correlation coefficient between ZRADSQ and Severity Scoring of Atopic Dermatitis (SCORAD) was 0.40 (P < 0.001). The reliability was also good, with a Cronbach's alpha value for ZRADSQ of 0.84, a split-half coefficient of 0.75, and a test-retest reliability coefficient of 0.98. The standardized effect size and standardized response mean were close to or larger than 1, which indicated moderate to good responsiveness. Conclusions: The ZRADSQ demonstrates promising reliability, validity, and responsiveness. It can be used to determine whether Zheng-specific or symptom-specific treatments relieve the symptom that is most bothersome the patient.