C3 and Hypertension: The validation cohort showed a notably higher serum creatinine level [74.40 (61.60, 90.20) μmol/L vs. 65.30 (53.40, 75.30) μmol/L, p = 0.007] and proportion of hypertension [39 (49%) vs. 13 (26%)] and lower serum C3 level [1.18 (0.97, 1.32) g/L vs. 1.06 (0.95, 1.19) g/L, p = 0.037] than the discovery cohort.