What are the best outcome measures for assessing quality of life in plaque type psoriasis? A systematic review of the literature

Background The assessment of health-related quality of life (QOL) is important in psoriasis. Despite this, among the wide variety of QOL questionnaires used in psoriasis, there is no consensus as to which is the best. Objective The objective of this systematic review was to identify which of these measurements have acceptable evaluation criteria for both monitoring disease and research purposes. We looked at validity, reliability, sensitivity to change (responsiveness) and acceptability, which are common criteria for any score and specific criteria for QOL questionnaire. Materials and Methods We performed a systematic review of all clinical studies investigating the QOL of psoriasis patients, published between January 1988 and June 2009. Results Twenty-one QOL questionnaires were identified. Eight of these satisfied most of the validation criteria; they were multidimensional and had been used in clinical research: short form 36 (SF 36), Dermatology Life Quality Index (DLQI), Skindex 29, Skindex 17, Dermatology Quality of life Scale (DQOLS), Psoriasis Disability Index (PDI) Impact of Psoriasis Questionnaire (IPSO) and Psoriasis Index of Quality of Life (PSORIQOL). Construct validity, content validity and internal consistency were adequately assessed and good performance was achieved for all questionnaires. Reproducibility (undetermined for Skindex 17) and acceptability were good for all questionnaires. Sensitivity to change was determined good for the SF36, DLQI, Skindex 29 and PDI. Item bias, unidimensional structure and cross-cultural equivalence were poor for all but the Skindex 17 and SF36 questionnaires. Conclusion On the basis of this systematic review, we can conclude that the DLQI is easy to use in clinical practice because of its brevity and simplicity. SF36 is widely used in clinical trials. Skindex 29 and Skindex 17, although rarely used, are interesting because of their cross-cultural validation.