Hierarchically Optimal Classification Tree Analysis of Adverse Drug Reactions Secondary to Warfarin Therapy

Robert C. Soltysik & Paul R. Yarnold

Optimal Data Analysis, LLC

Identification and detection of adverse drug reactions (ADRs) is critical to patient safety improvement, and warfarin is a medication known to be associated with a high rate of ADRs. Hierarchically optimal CTA was used to predict ADRs attributable to medications taken in addition to warfarin, for a sample of 2,289 hospital in-patients. A model involving five medications was identified, with relatively high ADR rates identified for patients, already on warfarin, who also received zolpidem tartrate, tamsulosin HCL, famotidine, nitroglycerin, and rofecoxib. The CTA model achieved moderate classification accuracy (ESS=38.0), correctly classifying 1,323 of 2,246 patients (58.9%) without an ADR, and 34 of 43 patients (79.1%) experiencing an ADR.

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