Multivariable logistic regression model weighting, which involved sampling weights of cystatin C (1999–2002) and adjusting them for gender and race, revealed that SI ≤ 68 was a predictive factor of sarcopenia (tertile 1 vs. tertile 3: OR=3.67, 95% CI: 1.52–8.87, p=0.004; tertile 2 vs. tertile 3: OR=1.79, 95% CI: 0.75–4.28, p=0.191; tertile 1 vs. tertile 2: OR=2.05, 95% CI: 1.15–3.64, p=0.014). The gene discussed is CST3; the disease is sarcopenia.