Papers of the Week

Serum alkaline phosphatase (ALP) levels are related to high-turnover bone disease and reflect vascular calcification and inflammation. ALP has been reported to have a prognostic impact in various cohorts including chronic kidney disease. This study investigated whether preoperative serum ALP level could be used for predicting mortality in patients undergoing kidney transplantation. We retrospectively reviewed 1,718 patients who underwent kidney transplantation between November 2005 and June 2017. Finally, 1,533 patients who met the inclusion criteria were classified into tertiles based on preoperative serum ALP level (< 51, 51-72, > 72 IU/L). The incidence of mortality was compared among the three tertiles, and a stepwise logistic regression analysis was performed to evaluate the predictors for mortality. The incidence of 3-year mortality was the highest in the third tertile (1.0% vs. 2.5% vs. 4.4% in the first, second, and third tertile, respectively, p = 0.003). The third tertile of ALP level (odds ratio [OR] 1.855, 95% CI 1.192-2.886, p = 0.006), age (OR 1.052, 95% CI 1.022-1.082, p = 0.011), and history of hypertension (OR 0.401, 95% CI 0.210-0.765, p = 0.006) remained as independent predictors of mortality. Preoperative serum ALP level was significantly higher in the non-survivor group than in the survivor group (58.00 [44.00-76.00] vs. 75.00 [56.25-113.00], p = 0.003). The optimal cut-off value of serum ALP to predict 3-year mortality was 71 IU/L (area under the curve 0.636, 95% CI 0.554-0.719, p = 0.003). Therefore, preoperative serum ALP level was an independent predictor of 3-year mortality in patients undergoing kidney transplantation.