Epidemiology and Health Services Research Development of the PSORIQoL, a psoriasis-specific measure of quality of life designed for use in clinical practice and trials S.P.McKENNA, S.A.COOK, D.WHALLEY, L.C.DOWARD, H.L.RICHARDS,* C.E.M.GRIFFITHS* AND D.VAN ASSCHE† Galen Research, Enterprise House, Lloyd Street North, Manchester M15 6SE, U.K. *The Dermatology Centre, University of Manchester, Hope Hospital, Manchester M6 8HD, U.K. †Novartis Pharma AG, Basel, Switzerland Accepted for publication 28 March 2003 Summary Background Patients with psoriasis have significant impairment in their quality of life (QoL). Several patient-completed instruments are available to measure outcome in dermatological conditions but these primarily focus on severity of disease rather than on QoL. Objectives To develop a new instrument specifically designed to measure QoL in psoriasis—the Psoriasis Index of Quality of Life (PSORIQoL). Methods The content of the instrument was derived from qualitative interviews with 62 psoriasis patients in the U.K., Italy and the Netherlands. Content analysis of the interview transcripts from the three countries identified potential items for the questionnaire. All further stages of the project were conducted in the U.K. only. Face and content validity were determined by means of a focus group held with seven psoriasis patients and face-to-face interviews with a further 21 patients. A new draft version of the PSORIQoL, together with the Dermatology Life Quality Index (DLQI) and the General Well-Being Index (GWBI), were completed by a new sample of psoriasis patients con- tacted by mail, in order to determine construct validity. A subsample of the respondents completed a similar package 2 weeks later, to assess reproducibility (reliability). Results The first version of the PSORIQoL consisted of 61 items covering the needs identified in the interviews as having been affected by psoriasis or its treatment. These included fear of negative reactions from others, self-consciousness and poor self-confidence, problems with socialization, physical contact and intimacy, limitations on personal freedom and impaired relaxation, sleep and emotional stability. Following the focus group and field-test interviews, a new draft measure con- sisting of 45 items was completed by 148 patients, 88 of whom completed and returned a similar package 2 weeks later. Application of Rasch analysis identified a final 25-item version of the PSORIQoL. This version had a test–retest reliability coefficient of 0®89, indicating good reproduci- bility. The levels of association with the DLQI and PGWB indicated that the PSORIQoL measures a related but distinct construct. Conclusions The PSORIQoL appears to be a practical, reliable and valid instrument for measuring the impact of psoriasis on QoL. It remains necessary to establish the instrument’s responsiveness to changes in QoL associated with treatment. Key words: psoriasis, PSORIQoL, quality of life, questionnaire Psoriasis is a chronic, incurable and disfiguring skin disease. The aim of treatment is to minimize the extent and severity of psoriasis and to reduce the impact on patients’ quality of life (QoL). 1 Psoriasis has a major impact on QoL. Fried et al. 2 found that half of psoriasis patients studied had moderate to extreme levels of anxiety, depression and anger. High scores were obtained on the General Health Questionnaire (a measure of psychiatric impair- ment) by 30% of psoriasis outpatients and 60% of those Correspondence: Stephen P.McKenna. E-mail: smckenna@galen-research.com British Journal of Dermatology 2003; 149: 323–331. Ó 2003 British Association of Dermatologists 323