In a study of 350 patients with PAD by Yang et al., serum cystatin, when increased by ≥5% at 24 h post-contrast medium administration for peripheral arterial angiography, was found to be an independent predictor for 1-year major adverse events (HR: 3.576, 95% CI: 1.354–9.447, p = 0.010) [35]. Here, CST4 is linked to peripheral arterial disease.