Derivation and validation of a disease-specific risk score for cardiac risk stratification in chronic kidney disease.

Objective. Cardiac events (CE; cardiac death, non-fatal myocardial infarction and acute coronary syndrome) are the principal causes of death in patients with chronic kidney disease (CKD). We sought to devise and validate a cardiac risk score to risk-stratify patients with CKD. Methods. Clinical history and biochemical data were obtained in 167 CKD patients. CE were recorded over a median follow-up of 22 months. The hazard ratio (HR) of each independent variable using Cox regression analysis was used to derive a cardiac risk score for the prediction of events. The cardiac risk score was then applied to a validation population of 99 CKD patients to confirm its validity in predicting CE. Results. CE occurred in 20 patients in the derivation group. The independent predictors of CE were cardiac history (HR 9.83, P = 0.001), body mass index (BMI; HR 1.15, P = 0.002), dialysis duration (HR 1.24, P = 0.004) and serum phosphate (HR 4.29, P = 0.001). The resulting cardiac risk score (range 26-67) gave an area under the receiver operating characteristic curve of 0.86. CE occurred in 25 patients in the validation group; the ROC curve area was similar (0.84, P = 0.11). An optimal cardiac risk score cut-off of 50 assigned high risk to 29% of the derivation and 35% of the validation group (P = 0.26). CE occurred in 35 and 57% of the high-risk derivation and validation groups, respectively (P = 0.09), and in 2 and 8% of the low-risk groups (P = 0.15). Conclusion. Application of a cardiac risk score using cardiac history, dialysis duration, BMI and phosphate identifies CKD patients at risk of future CE.