Symptom Experience and Content Validity of the Psoriasis Symptom Scale (PSS) in Patients with Generalized Pustular Psoriasis (GPP).

Generalized pustular psoriasis (GPP) is a severe rare disease, including redness and boils that sometimes come with fever and other general symptoms. This study asked patients with GPP about their key symptoms, and whether the Psoriasis Symptom Scale (PSS) is relevant to them as patients. The PSS is a questionnaire with the symptoms pain, itching, burning, and redness. We searched the literature and interviewed clinical experts to guide the patient interviews. Patients were recruited through clinical sites and the National Psoriasis Foundation (NPF). The interviews discussed GPP symptoms and the PSS questionnaire. Patients with GPP were also asked about commonly experienced symptoms in a workshop. Most patients had moderate to severe GPP. Patients in both the interviews and workshop described experiencing pain, redness, itch, burning, and discomfort with their boils. During interviews, the patients said the PSS questionnaire was easy to understand. Patients in the workshop also found the PSS to be relevant and easy to understand. Patients agreed the symptoms in the PSS, pain, redness, itch, and burning, were common and important. Study results support the PSS for use with patients in clinical trials.