Iatrogenic injuries are common among hospitalized patients and are frequently preventable. The Institute of Medicine (IOM) reported that an estimated 44,000 to 98,000 people die each year in the United States at least in part due to medical error. The accuracy of the IOM study has been questioned by some experts while supported by others, but this controversy does not detract from the fact the injuries due to medical errors are a significant problem. The Harvard Medical Practice Study has shown that many adverse events experienced by patients are due to complications of medication use. Subsequent studies have confirmed that adverse drug events (ADEs) are common, costly, and often severe.