The Relationship Between Neutrophil-to-Lymphocyte Ratio, Platelet-to-Lymphocyte Ratio, and Systemic Immune-Inflammation Index Markers and Response to Biological Therapy in Patients with Psoriasis

Plaque psoriasis is a chronic, immune-mediated inflammatory skin disease characterized by the formation of thick, scaly plaques. The disease is driven by dysregulation of the immune response, primarily involving T-helper cells, which create a persistent inflammatory environment. In recent years, several biomarkers reflecting systemic inflammation have been identified, including indices derived from a complete blood count, such as the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and Systemic Immune-Inflammation Index (SII). The aim of our study was to explore the role of these markers in patients with psoriasis undergoing biological treatment. Medical records of 159 patients with plaque psoriasis receiving biologics were retrospectively reviewed. The NLR, PLR, and SII values were calculated from the hemograms of the patients. Additionally, demographic and psoriasis severity data were analyzed. During the 18-month follow-up, the mean NLR, PLR, SII, and CRP values were significantly decreased in comparison to the baseline (<i>p</i> < 0.05). No significant differences between anti-TNF, anti-IL-12/23, anti-IL-17, and anti-IL-23 drugs were identified (<i>p</i> > 0.05). The initial values of NLR, PLR, and SII were positively correlated with psoriasis severity. No relationship between the analyzed biomarkers and age, sex, psoriasis duration, and prior exposure to biological drugs was identified. CBC-derived biomarkers may be useful for monitoring inflammation reduction in psoriasis patients treated with biological drugs.