Letters Section Editor: Robert M. Golub,
MD, Senior Editor.
To the Editor: Dr Fonarow and colleagues1 estimate a risk model for in-hospital mortality in
acutely decompensated heart failure using a large data set (>33 000 patients)
and validate it on an equally large independent data set. However, their conclusion
that a classification and regression tree (CART) model performs better than
a linear logistic model in predicting the risk of death in patients with acutely
decompensated heart failure is surprising. In the independent data set, the
CART model yielded an area under the receiver operating characteristic curve
(AUROC) of 0.668 compared with 0.757 for the logistic model. Although apparently
modest, this represents a large difference in performance. A useless model
would on average have an AUROC of 0.5. Subtracting 0.5 from the AUROC and
considering a scale from 0 to 0.5 (the upper limit), the relative improvement
offered by the logistic model is (0.257-0.168)/0.168 or 53%, which is considerable.
Royston P, Altman DG. Risk Stratification for In-Hospital Mortality in Acutely Decompensated Heart Failure. JAMA. 2005;293(20):2467-2468. doi:10.1001/jama.293.20.2467-c