Objective—To prospectively evaluate a survival prediction
index (SPI) in dogs admitted to intensive care
units (ICU) and to generate and test an improved SPI
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, severity
of underlying physiologic derangement, and extent of
physiologic reserve; outcome was defined as dogs
that survived or did not survive until 30 days after
admission to the ICU. Probabilities of survival were
calculated, using an established model (SPI). We then
performed another logistic regression analysis, thereby
reestimating the variables to create the new SPI2.
Cross-validation of the models obtained was performed
by randomly assigning the total sample of 624
dogs into an estimation group of 499 dogs and validation
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, indicating
little loss in predictive accuracy.
Conclusions and Clinical Relevance—The new
SPI2 objectively stratified clinical patients into groups
according to severity of disease. This index could provide
an important tool for clinical research. ( Am J Vet