ADVERSE DRUG EVENTS (ADEs) are the most common type of iatrogenic injury occurring in hospitalized patients.1,2 Adverse drug events have been reported to occur during 1% to 30% of hospital admissions, depending on the operational definition of ADE and the rigor with which they are sought.2-9 A recent meta-analysis reported an overall incidence of 6.7% for serious adverse drug reactions (a term that excludes injury secondary to errors in prescribing and administration).10 For every 1000 patients admitted to a hospital, approximately 3 will die3,10,11 and 1 will suffer serious long-term disability2 due to ADEs. The mean direct cost of an inpatient ADE ranges from $1900 to $5900.4,6,12