The Development of a Patient-Reported Outcome Measure for Assessment of Genital Psoriasis Symptoms: The Genital Psoriasis Symptoms Scale (GPSS)

INTRODUCTION: Patient-reported outcome measures (PROs) specific for genital psoriasis (GenPs) have not been described. METHODS: In this cross-sectional, qualitative study in patients with moderate-to-severe GenPs, we sought to develop a PRO useful for GenPs symptom assessment. A literature review was performed to identify relevant psoriasis or GenPs symptoms and existing PROs that may be useful in the evaluation of symptom severity in GenPs patients. The literature review findings were discussed with clinicians, and then patients with GenPs. RESULTS: Relevant psoriasis or GenPs symptoms from the literature review included itch, pain, scaling, redness/erythema, and stinging/burning. The validity of these symptoms for GenPs and potentially relevant PROs was corroborated by clinical experts. After gap analysis, a draft symptom scale consisting of Numeric Rating Scale (NRS) items was constructed. We then conducted interviews with GenPs patients (n = 20) to support content validity and use of the draft symptom NRS items in routine practice and in clinical trials. Participants identified and confirmed relevant symptoms and evaluated the utility of the draft PRO. A new PRO was developed: the Genital Psoriasis Symptoms Scale (GPSS). Cognitive debriefing and cultural adaptation/translation interviews with a second group of patients confirmed cultural appropriateness of the GPSS. CONCLUSION: The GPSS may be useful for assessing symptoms before, during, and after treatment in routine clinical practice and in clinical trials involving patients with GenPs. FUNDING: Eli Lilly & Company. PLAIN LANGUAGE SUMMARY: Plain language summary available for this article. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13555-017-0213-2) contains supplementary material, which is available to authorized users.