Comparison of Severity Assessment Methods in Generalized Pustular Psoriasis: A Single-Center Study

Generalized pustular psoriasis (GPP) is a rare and potentially life-threatening autoinflammatory skin disease characterized by widespread pustules and systemic inflammation. Accurate disease severity assessment is essential for appropriate management. To evaluate GPP severity, several scoring systems have been developed, including the Generalized Pustular Psoriasis Physician Global Assessment (GPPGA), Generalized Pustular Psoriasis Area and Severity Index (GPPASI), and Investigator's Global Assessment (IGA). In Japan, the Japanese Dermatological Association (JDA) score is commonly used, incorporating systemic inflammatory parameters, such as fever, serum C-reactive protein (CRP) level, and serum albumin level with skin conditions. This study aimed to compare the JDA score with other severity assessment tools and examine their correlation with the length of hospitalization. We retrospectively analyzed 23 hospitalizations of 13 patients with GPP admitted to Nihon University Itabashi Hospital between 2014 and 2024. The JDA score showed a significant positive correlation with the length of hospitalization (r_s = 0.482, p = 0.023), whereas the GPPGA, GPPASI, and IGA scores did not show any significant correlation. CRP levels, albumin levels, and the CRP/albumin ratio were significantly correlated with the length of hospitalization and GPPGA and GPPASI scores. These findings suggest that the JDA score, which integrates cutaneous symptoms and systemic inflammatory parameters, provides a more comprehensive and clinically relevant assessment of GPP severity than other scoring systems. Additionally, serum CRP and albumin levels should be considered in the evaluation of disease activity and prediction of clinical outcomes.