Serum biomarkers for diagnosis and severity evaluation in knee osteoarthritis.

Objective: This study aimed to investigate the serum levels of signal transducer and activator of transcription 3 (STAT3), vascular endothelial growth factor (VEGF), and interleukins (IL)-2 and IL-4 in patients with knee osteoarthritis (KOA), and to evaluate their diagnostic value for disease severity.

Methods: A total of 115 KOA patients and 50 healthy controls were enrolled. Serum levels of STAT3, VEGF, IL-2, and IL-4 were measured in all participants. The correlations between these biomarkers and KOA severity were further analyzed.

Results: Compared to healthy controls, KOA patients exhibited significantly elevated serum levels of STAT3, VEGF, IL-2, and IL-4 (all P < 0.05). Following standard treatment, the concentrations of these biomarkers significantly decreased. Receiver operating characteristic (ROC) curve analysis revealed that the area under the curve (AUC) values for diagnosing KOA were 0.710 for STAT3, 0.726 for VEGF, 0.704 for IL-2, and 0.797 for IL-4. Furthermore, the serum concentrations of these factors showed strong positive correlations with KOA severity (r = 0.436 for STAT3, r = 0.467 for VEGF, r = 0.497 for IL-2, and r = 0.509 for IL-4). Their AUC values for assessing disease severity were 0.723 (STAT3), 0.742 (VEGF), 0.769 (IL-2), and 0.757 (IL-4). Combined detection of these biomarkers improved diagnostic accuracy.

Conclusions: Abnormally elevated serum levels of STAT3, VEGF, IL-2, and IL-4 in KOA patients are closely associated with disease severity and treatment efficacy. These biomarkers may serve as auxiliary indicators for KOA diagnosis and severity assessment.