ORIGINAL ARTICLE Psychometric properties of the Chinese version of dermatology life quality index (DLQI) in 851 Chinese patients with psoriasis Z. He, †, ** C. Lu, ‡, * M.K.A. Basra, § A. Ou, † Y. Yan, ‡, ** L. Li –, ** Departments of † Clinical Epidemiology and ‡ Dermatology, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China § Department of Dermatology and Wound Healing, Cardiff University, Cardiff, UK – The Central Laboratory, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China **Post-Doctoral Research Centre of Guangzhou University of Chinese Medicine, Guangzhou, China *Correspondence: C. Lu. E-mail: luchuanjian888@vip.sina.com Abstract Background The Dermatology Life Quality Index (DLQI) is one of the most frequently used scales to evaluate the impact of skin disease on patients’ quality of life (QoL). There has not been psychometric evaluation of the Chinese version of DLQI in Chinese patients with psoriasis. Objective The objective of this study was to evaluate the psychometric properties of the Chinese version of DLQI. Methods Patients with psoriasis (‡18 years old) visiting nine hospitals in various regions of China were enrolled in the study. The DLQI, Psoriasis Disability Index (PDI) and Health Survey Short Form (SF-36) were completed. Severity of psoriasis was assessed by the Psoriasis Area Severity Index (PASI). Reliability was estimated by internal consistency. Validity was assessed using known-groups comparison, convergent validity and construct validity. Results In all, 851 patients were included in the study. The internal consistency reliability of the DLQI was high (Cronbach’s alpha = 0.91). Known-groups comparison showed that the DLQI discriminated well among patients who differed in age, geographical region, duration of psoriasis and the PASI score. Evidence of convergent validity of the DLQI was proved by high correlations with the PDI and four subscales of SF-36 (role-physical, bodily pain, social functioning and role-emotional): r = 0.52–0.78. Construct validity was proved by the presence of one-factor structure that accounted for 55.9% of the variance and fitted well into the unidimensional model. Conclusion The Chinese version of DLQI is a reliable and valid measure to assess patient-reported impact of skin disease and could be used in QoL and health outcome studies on Chinese psoriasis patients. Received: 14 July 2011; Accepted: 7 November 2011 Conflicts of interest The authors declare that they have no competing interests. Funding sources This study was funded by the Financial Industry Technology Research and Development Program of Guangdong Province, the Post-doctoral Research Foundation of Guangzhou University of Chinese Medicine, and the Post- doctoral Research Foundation of Guangdong provincial Hospital of Traditional Chinese Medicine. Introduction Psoriasis is a chronic and incurable skin disease that affects approximately 2–3% of European and American people. 1,2 The skin signs of thick scaling red plaques associated with itching and arthritis can have profound effects on the quality of life (QoL) of the patients. 3,4 Lower prevalence rate (0.4–1.2%) of psoriasis in Chinese population have been reported, 5–7 but the impact of pso- riasis on QoL of Chinese patients is still worthy to be assessed when clinical decision is made for designing and selecting suitable health care programmes. Moreover, less attention has been paid to the QoL of patients with psoriasis in China than in other coun- tries. One of the main reasons is a lack of suitable instruments in Chinese that have been developed or adapted according to estab- lished scientific criteria and attributes. 8 The assessment of the impact of psoriasis on QoL has been extensively documented and various dermatology and psoriasis- specific instruments have been developed to measure this impact over the past two decades. 9–14 In looking for instruments for ª 2011 The Authors JEADV 2011 Journal of the European Academy of Dermatology and Venereology ª 2011 European Academy of Dermatology and Venereology DOI: 10.1111/j.1468-3083.2011.04371.x JEADV