Variability in drug formularies and implications in decision support.

Formularies are highly variable, which limits physicians ability to prescribe cost effective medications for their patients. In this study we explore the composition of 3,346 formularies in terms of outpatient prescription coverage, medication class coverage, and cost implications. Our analysis revealed that 42% of formularies are duplicative and that the unique formularies contain variability for medications that contribute little in terms of cost or overall use. These results lead us to believe the number and complexities of formularies can be dramatically reduced leading to more intuitive decision support for physicians when writing prescriptions.