This study aimed to evaluate the utility of netrin 1, CRP (C-reactive protein), and ESR (erythrocyte sedimentation rate) biomarkers for distinguishing between psoriatic arthritis (PsA) and psoriasis. This study included 44 patients with PsA and 44 with psoriasis. CASPAR (-Classification criteria for psoriatic arthritis) was used to classify PsA patients, and the PASI (-Psoriasis Area and Severity Index) was used to determine the degree of psoriatic plaques. Serum netrin 1 levels were measured using a commercial, ready-to-use ELISA kit that employs a quantitative immunoassay. Serum netrin 1 and ESR levels were similar between the PsA and psoriasis groups, but the median netrin 1 values were significantly higher in the PsA subtype with axial involvement than in the non-PsA subtype (respectively, 69.9 [64.0-97.6], 58.7 [56.2-64.0], p: 0.002). CRP levels were significantly higher in the PsA group than in the psoriasis group (B: - 0.134, OR [95% CI]: 0.874 [0.783-0.977], p: 0.018). A cut-off value of 12.05 for CRP was found to have a specificity of 27.3% and a sensitivity of 97.7% in distinguishing patients with PsA from those with psoriasis (AUC [95% CI]: 0.699 [0.590-0.809], p: 0.01). Netrin 1 is not a significant biomarker for distinguishing PsA from psoriasis, but it may be a potential biomarker for identifying the PsA subtype with axial involvement. Although CRP is a sensitive biomarker for distinguishing PsA from psoriasis, its specificity is low.
