OBJECTIVES: To understand patient-reported symptoms of generalized pustular psoriasis (GPP), a rare and severe disease, characterized by recurrent flares that consist of a disseminated erythematous skin rash with sterile neutrophil-filled pustules and may include systemic symptoms. Another objective was to confirm the relevance and content validity of the Psoriasis Symptom Scale (PSS) in GPP.

METHODS: A targeted literature review and clinical expert interviews were conducted to develop a qualitative discussion guide for semi-structured, one-on-one interviews with GPP patients. These interviews involved a combined concept elicitation to determine disease-specific symptoms and cognitive debriefing of the PSS. Interviews were conducted in-person or by telephone by three different outcomes research scientists trained in qualitative research.

RESULTS: Seven patients with a GPP diagnosis, based on clinician verification were recruited in the US. The median age of patients was 58 years (range: 40–70). Most were female (n=5; 71%), a majority were Caucasian (n=4, 57%); 3 (43%) were African American. Four (57%) patients self-reported moderate GPP, two (29%) self-reported severe GPP, and one (14%) self-reported very mild disease. During concept elicitation, patients indicated pustules as the underlying cause of their symptoms. The most commonly reported symptoms or signs were pain, redness, discomfort, and inflammation/swelling (n=7, 100%), followed by itching, burning, irritation, dryness/dry skin, and soreness (n=6, 86%).

Burning, itch, pain, and redness, the symptoms included in the PSS, were considered important to GPP patients. Signs such as flaky/peeling skin and inflammation/swelling are better as clinician-report.

CONCLUSIONS: GPP patients are significantly burdened with pain, redness, itching, burning, dryness, and swelling. Patients thought the PSS measure was relevant for GPP, straightforward, and easy to understand. Results from this qualitative study provide support for the content validity of the PSS for use as a clinical trial endpoint in GPP.