Evaluating Psoriasis Severity Using the Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio: A Systematic Review and Meta-Analysis.

Currently, there is a lack of reliable laboratory tests for monitoring the severity of psoriasis and evaluating treatment efficacy. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are novel parameters of systemic inflammation. This study aimed to evaluate the association between NLR, PLR and psoriasis. Databases were systematically searched for studies up to May 2025. Publications meeting any of the following criteria were eligible: (1) comparison of NLR and PLR between psoriasis patients and healthy controls, (2) correlation coefficient of NLR and PLR and Psoriasis Area Severity Index (PASI) score, and (3) NLR and PLR before and after 3-4 months of biologic therapies. The pooled results showed that the NLR and PLR were significantly higher in patients with psoriasis than in controls (standardised mean difference [SMD] = 0.645, 95% confidence interval [CI] 0.514-0.775; SMD = 0.467, 95% CI 0.304-0.630). Both NLR and PLR were significantly correlated with the PASI score (r = 0.214, 95% CI 0.178-0.250; r = 0.161, 95% CI 0.114-0.207). The NLR and PLR significantly decreased after receiving tumour necrosis factor-α blockers, ustekinumab, and interleukin-23 inhibitors for 3-4 months. The NLR and PLR may serve as convenient tools in monitoring psoriasis treatment and indicators of systemic inflammation.