Serum growth differentiation factor-15 levels in Behçet's syndrome: A cross-sectional study

Behçet's syndrome (BS) is a heterogeneous systemic vasculitis characterized by chronic inflammation and immune dysregulation. Growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β superfamily, has been implicated in chronic inflammatory and immune stress responses. This study aimed to evaluate serum GDF-15 levels in patients with BS and to investigate their relationship with disease activity and clinical parameters. This cross-sectional study included 49 patients diagnosed with BS according to International Study Group criteria, as well as a control group of 33 healthy individuals. Demographic characteristics, clinical features, laboratory parameters, treatments, and disease activity scores were recorded. Serum GDF-15 levels were measured using a commercial enzyme-linked immunosorbent assay. Statistical analyses were performed to compare groups and to evaluate associations between GDF-15 levels and clinical and laboratory variables. In the unadjusted comparison, serum GDF-15 levels were significantly higher in patients with BS than in controls (P = .016). However, GDF-15 levels were not associated with disease activity scores. In multivariable logistic regression adjusting for sex and BMI, GDF-15 was no longer an independent predictor of BS (adjusted P = .53), whereas sex (OR = 5.61, P = .006) and BMI (OR = 0.86, P = .024) remained independently associated with the group, indicating that the unadjusted GDF-15 difference largely reflects demographic confounding rather than a disease-specific effect. No significant correlations were observed between GDF-15 levels and classical acute-phase reactants. This study underscores the importance of recognizing negative biomarker findings to prevent overinterpretation of biomarker utility. Although serum GDF-15 levels were higher in patients with BS in the unadjusted comparison, this difference was no longer statistically significant after adjustment for sex and BMI. GDF-15 levels were also not associated with disease activity, limiting their utility as a disease-specific biomarker. Further longitudinal studies are needed.