The cost of adverse drug events in ambulatory care.

BACKGROUND: Many justifications for ePrescribing predict savings achieved by reducing the number of adverse drug events (ADEs) in the ambulatory setting however, there is little evidence from which to estimate the size of these savings. Estimating the cost of ADEs in the ambulatory setting would improve the reliability of these predictions. METHODS: We identified patients with potential ADEs in a primary care practice setting and characterized the patient's age along with charge and utilization indicators for 6 weeks pre- and post-event. We then used linear regression to determine charges attributable to an ADE. RESULTS: Charges were higher for patients following an ambulatory visit who were determined to have ADEs. This occurred in a linear fashion: 2 ADEs ($4,976); 1 ADE ($2,337); and no ADEs ($1,943). The charge attributable to a single ADE is $643 (2001 US dollars) or $926 (cost adjusted to 2006 US dollars). CONCLUSIONS: Patients with ADEs incur greater charges. The charges attributable to an ambulatory ADE are a significant cost to the health care delivery system on the order of $8 billion annually.