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.