Comparison of hematological inflammatory markers and comorbid conditions in patients with psoriasis vulgaris and lichen planus.

Background and objective: Psoriasis vulgaris (PV) and lichen planus (LP) are inflammatory skin diseases. Systemic inflammatory markers, which may indicate inflammation in these diseases, have been investigated in various studies. This research focused on analysing the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and RDW values in patients with PV and LP. Additionally, we investigated their associations with comorbidities and assessed the diagnostic value of NLR in identifying psoriatic arthritis (PsA).

Material and methods: The study included 110 patients with LP and 140 patients with PV who presented to the dermatology outpatient clinic between 2022 and 2024. Age, gender, NLR, PLR, SII, RDW values, and accompanying comorbid diseases of the patients were recorded. Differences in NLR based on disease type and comorbid conditions were analysed. Additionally, in patients with PV, the relationship between the presence of (PsA) and NLR was evaluated. Cut-off values, sensitivity, specificity, and AUC values were calculated.

Results: We observed that the PV group had significantly elevated NLR and PLR values in comparison to the LP group (p < 0.001, p = 0.027). For NLR: (AUC: 0.669; 95% CI: 0.607-0.727); cut-off value: ≤2, sensitivity: 66.36%, specificity: 66.43%; p < 0.0001.For PLR: (AUC: 0.584; 95% CI: 0.520-0.646); cut-off value: ≤109.35, sensitivity: 55.45%, specificity: 63.57%; p = 0.0221. In the group with PsA, A significant elevation in NLR was observed (p = 0.043). For NLR in this group: (AUC: 0.621; 95% CI: 0.535-0.701); cut-off value: >2.15, sensitivity: 83.33%, specificity: 47.27%; p = 0.0175.

Conclusions: NLR and PLR may be useful markers in distinguishing PV. NLR, with a higher AUC and specificity compared to PLR, may be considered a stronger marker. Furthermore, due to its high sensitivity for PsA, NLR could be more suitable for screening purposes rather than diagnosis.