Association between serum soluble Klotho level and outcome in patients on maintenance hemodialysis

Objective To determine the relationship between serum soluble Klotho (sKL) level and adverse outcome in maintenance hemodialysis (MHD) patients. Methods One hundred and twenty nine cases of MHD patients were collected prospectively. Serum sKL was detected by ELISA. Abdomen lateral plain was used as a criterion to determine the abdominal aortic calcification. The abdominal aortic calcification score (AAC) was calculated. Cox regression analysis was used to determine the risk factor of cardiovascular death (CVD) in MHD patients. Kaplan-Meier showed the relationship between sKL and CVD in MHD patients. Results There were 27 cases (20.9%) of all-cause death and 19 cases (14.7%) of cardiovascular death. The median sKL was 612.6(379.2-816.6) ng/L, and log[iPTH] was an independent factor of sKL concentration. Low sKL had high AAC and CVD death rate. Kaplan-Meier method showed that the all-cause death rate was similar between two groups, and CVD death rate increased significantly in low sKL patients (P=0.036). Cox regression indicated that lower sKL level was associated with high CVD death rate [OR=0.352, 95% CI(0.127-0.977), P=0.045].After adjustment for the general condition, biochemical indicators, the relationship still existed [OR=0.331, 95% CI (0.117-0.933), P=0.037]. In no or mild vascular calcification patients (AAC≤4), compared with high sKL patients, low sKL patients had no significant difference rate in all-cause mortality. The CVD mortality was significantly higher in high sKL (P=0.035) compared with low sKL. In severe calcification group (AAC>4), all-cause death and CVD death rates were similar between different sKL groups (P=0.991 and 0.522, respectively). Conclusions Lower sKL has the high CVD death rate and sKL level decreasing is an independent risk factor for CVD death in MHD patients. The lower sKL concentration in MHD patients with no or mild calcification may predict CVD mortality. This study suggests that sKL levels may be helpful in predicting the outcome of patients with MHD. Key words: Renal dialysis; Cardiovascular diseases; Prognosis; Soluble Klotho; Abdominal aorta calcification