Evaluation of the survival prediction index as a model of risk stratification for clinical research in dogs admitted to intensive care units at four locations

Objective-To prospectively evaluate a survival prediction index (SPI) in do gs admitted to intensive care units (ICU) and to generate and test an impro ved SPI tie, SPI2). Sample Population-Medical records of 624 critically ill dogs admitted to an ICU. Procedure-Data were collected from dogs within 24 hours after admission to an ICU. Variables recorded reflected function of vital organ systems, sever ity of underlying physiologic derangement, and extent of physiologic reserv e; outcome was defined as dogs that survived or did not survive until 30 da ys after admission to the ICU. Probabilities of survival were calculated, u sing an established model (SPI). We then performed another logistic regress ion analysis, thereby reestimating the variables to create the new SPI2. Cr oss-validation of the models obtained was performed by randomly assigning t he total sample of 624 dogs into an estimation group of 499 dogs and valida tion group of 125 dogs. Results-Testing of SPI resulted in an area under the curve (AUC) of 0.723. Testing of SPI2 revealed an AUC of 0.773. A backwards-elimination procedure was used to create a model containing fewer variables, and variables were sequentially eliminated. The AUC for the reduced model of SPI2 was 0.76, in dicating little loss in predictive accuracy. Conclusions and Clinical Relevance-The new SPI2 objectively stratified clin ical patients into groups according to severity of disease. This index coul d provide an important tool for clinical research.