Analysis of Maryland poisoning deaths using classification and regression tree (CART) analysis.

Our study is a cross-sectional analysis of Maryland poisoning deaths for years 2003 and 2004. We used Classification and Regression Tree (CART) methodology to classify undetermined intent Maryland poisoning deaths as either unintentional or suicidal poisonings. The predictive ability of the selected set of variables (i.e., poisoned in the home or workplace, location type, where poisoned, place of death, poison type, victim race and age, year of death) was extremely good. Of the 301 test cases, only eight were misclassified by the CART regression tree. Of 1,204 undetermined intent poisoning deaths, CART classified 903 as suicides and 301 as unintentional deaths. The major strength of our study is the use of CART to differentiate with a high degree of accuracy between unintentional and suicidal poisoning deaths among Maryland undetermined intent poisoning deaths.