Plasma FSTL-1 as a noninvasive diagnostic biomarker for patients with advanced liver fibrosis

Reliable novel noninvasive biomarkers for the diagnosis of advanced liver fibrosis are urgently needed in clinical practice. We aimed to investigate the accuracy of plasma Follistatin-like protein 1 (FSTL-1) in the diagnosis of advanced liver fibrosis in chronic liver diseases.

We collected cross-sectional clinical data for a derivation cohort (n = 86) and a validation cohort (n = 431), totaling 517 subjects with liver biopsy. Advanced liver fibrosis was defined by the METAVIR pathological score (F ≥3). Dual cutoff values for diagnosis were explored. In the derivation cohort, plasma FSTL-1 levels were significantly elevated in patients with advanced liver fibrosis, with an AUROC of 0.85 (95% CI, 0.75-0.96). In the validation cohort, plasma FSTL-1 maintained good diagnostic performance, with an AUROC of 0.88 (95% CI, 0.83-0.92). Plasma FSTL-1 levels were significantly associated with individual histological features of the METAVIR scoring system, including interface hepatitis, lobular necrosis, and hepatocellular ballooning (p < 0.0001). A cutoff value ≤ 0.43 ng/mL was the optimal rule-out threshold, with a sensitivity of 84.62% (95% CI, 76.46%-90.30%) and a specificity of 79.51% (95% CI, 74.81%-83.53%), while ≥0.50 ng/mL was the best rule-in threshold, with a specificity of 86.41% (95% CI, 81.06%-90.43%) and a sensitivity of 70.67% (95% CI, 64.41%-76.23%).

Plasma FSTL-1 has high diagnostic accuracy and could potentially reduce the need for liver biopsy in identifying patients with advanced liver fibrosis.