Validation of risk adjustment models for in-hospital percutaneous transluminal coronary angioplasty mortality on an independent data set

OBJECTIVES We sought to validate recently proposed risk adjustment models f or in-hospital percutaneous transluminal coronary angioplasty (PTCA) mortal ity on an independent data set of high risk patients undergoing PTCA. BACKGROUND Risk adjustment models for PTCA mortality have recently been rep orted, but external validation on independent data sets and on high risk pa tient groups is lacking. METHODS Between July 1, 1994 and June 1, 1996, 1,476 consecutive procedures were performed on a high risk patient group characterized by a high incide nce of cardiogenic shock (3.3%) and acute myocardial infarction (14.3%). Pr edictors of in-hospital mortality were identified using multivariate logist ic regression analysis. Two external models of in-hospital mortality, one d eveloped by the Northern New England Cardiovascular Disease Study Group (mo del NNE) and the other by the Cleveland Clinic (model CC), were compared us ing receiver operating characteristic (ROC) curve analysis. RESULTS In this patient group, an overall in-hospital mortality rate of 3.4 % was observed. Multivariate regression analysis identified risk factors fo r death in the hospital that were similar to the risk factors identified by the two external models. When fitted to the data set, both external models had an area under the ROC curve >0.85, indicating overall excellent model discrimination, and both models were accurate in predicting mortality in di fferent patient subgroups. There was a trend toward a greater ability to pr edict mortality for model NNE as compared with model CC, but the difference was not significant. CONCLUSIONS Predictive models for PTCA mortality yield comparable results w hen applied to patient groups other than the one on which the original mode l was developed. The accuracy of the two models tested in adjusting for the relatively high mortality rate observed in this patient group supports the ir application in quality assessment or duality improvement efforts. (J Am Coll Cardiol 1999;34:692-7) (C) 1999 by the American College of Cardiology.