Clinical Disease Measures in Palmoplantar Pustulosis: A Scoping Review

Abstract

Background Palmoplantar pustulosis (PPP) is a rare, relapsing, disease characterized by pustules, pain, and fissuring. PPP is often combined with psoriasis, most commonly palmar plantar psoriasis, in clinical trials which further complicates our understanding of treatment response. Objective The objective of this scoping review is to describe all outcome measures (clinician-reported & patient-reported) used in previous PPP clinical trials. Methods A search was conducted in Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) for clinical trials and prospective cohort studies performed in adults with PPP, with an intervention and pre-determined outcomes collected at pre specified time points. Results The initial search identified 1839 records, of which 69 met our inclusion criteria. The studies were published between 1970–2023 and included a total of 3301 patients. The most common primary study outcome was the clinician-reported Palmoplantar Pustulosis Psoriasis Area Severity Index (ppPASI) ( n = 39, 56.5%) and an endpoint of 12 weeks ( n = 23, 33.3%). Other common clinician reported outcomes identified were pustule count ( n = 26, 37.7%) and the Physician Global Assessment ( n = 16, 23.2%) The majority of studies ( n = 43, 62.3%) did not include any patient reported outcome measures. Of those that did include patient reported outcome measures, the Dermatology Life Quality Index was most utilized ( n = 17, 24.6%), followed by symptoms-specific instruments measuring pain ( n = 11, 15.9%) and itch ( n = 6, 8.7%). Conclusions While the clinician-reported ppPASI has become the standard primary outcome in PPP clinical trials, there is still considerable heterogeneity and lack of specificity in the patient reported outcomes used.