Association between the neutrophil percentage-to-albumin ratio and generalized pustular psoriasis

Dear Editor, Generalized pustular psoriasis (GPP) is a rare and life-threatening subtype of psoriasis characterized by recurrent flares, systemic inflammation, and sterile pustules (1). Accurate biomarkers that reflect disease activity and treatment response are needed in clinical practice. The neutrophil percentage-to-albumin ratio (NPAR) is an emerging inflammatory marker that reflects both immune activation and nutritional status (2). However, its relevance in GPP remains poorly understood. This retrospective study aimed to evaluate the clinical utility of NPAR in GPP by comparing NPAR values among patients with GPP, psoriasis vulgaris (PsV), psoriatic arthritis (PsA), and healthy controls (HC). We also examined longitudinal changes in NPAR before and after treatment in GPP, and assessed its correlation with the generalized pustular psoriasis area and severity index (GPPASI) or with C-reactive protein (CRP), and the Severity Score for GPP. A total of 124 subjects were included: 13 GPP, 44 PsV, 37 PsA, and 30 HC. The GPP group consisted of 4 males and 9 females, with a median age of 58 years (range: 22-73), including 12 Japanese and 1 Chinese patient. NPAR values were significantly elevated in GPP patients compared to those with PsV (p = 0.0046), PsA (p = 0.0048), and HC (p = 0.0016), as determined by Kruskal-Wallis test followed by Dunn-Bonferroni post hoc test (Figure 1A). Further analyses were conducted to assess the impact of treatment on NPAR values within the GPP group. Post-treatment NPAR values significantly decreased compared to pre-treatment levels, as evaluated using Wilcoxon matched-pairs signed-rank test (p = 0.021; Figure 1B). We also evaluated potential correlations between NPAR and other relevant clinical indicators. The analysis revealed a strong positive correlation between NPAR and the GPPASI (r = 0.8636, p = 0.0012, n = 11; Figure 1C). A similarly strong positive correlation was observed between NPAR and CRP levels (r = 0.8352, p = 0.0007, n = 13; Figure 1D). In addition, NPAR also correlated strongly with the Severity Score (r =0.8695, p = 0.0009, n = 11; Figure 1E). The significant elevation of NPAR observed in GPP patients aligns well with current understanding of the pathogenic mechanisms involving neutrophil activation (3). Moreover, the inclusion of albumin levels in NPAR calculation offers additional clinical relevance. Given that lower albumin levels in GPP primarily result from increased vascular permeability associated with systemic inflammation (4,5). Capillary leak syndrome, a complication of GPP, may reflect the most severe clinical manifestation of this pathophysiology and is characterized by prominent edema, which can lead to respiratory failure and circulatory collapse (1). Therefore, the combination of neutrophil percentage and albumin in NPAR provides a comprehensive assessment of both inflammatory and vascular factors, thereby enhancing its clinical interpretability and applicability.The study further highlights the responsiveness of NPAR to therapeutic intervention. The significant reduction in NPAR post-treatment suggests its potential utility in monitoring therapeutic responses and disease progression. Given the observed NPAR changes correlating with clinical improvements, NPAR may offer clinicians a valuable tool for evaluating treatment effectiveness in realtime, aiding clinical decision-making and patient management.Limitations of this study include its retrospective design and relatively small sample size.Future prospective studies with larger cohorts are necessary to validate these findings and explore the predictive capabilities of NPAR regarding long-term disease outcomes.In conclusion, NPAR emerges as a promising biomarker that combines inflammatory and vascular indicators, strongly correlating with disease severity and systemic inflammation in GPP.