Since most errors occur at the prescribing step, computerized physician order entry (CPOE) with patient-specific decision support is a potentially powerful intervention for improving patient safety. Common prescribing errors include using the wrong drug or dosage form, incorrect dose calculation, not checking for allergies, and failure to adjust dosages in patients with renal or hepatic dysfunction [14]. CPOE systems work by (i) making sure that the order is legible and complete, including all necessary information, such as dose, route, and dosage form; (ii) checking for problems such as drug allergies and drug–drug interactions; (iii) providing dosage adjustment calculations based on clinical features such as weight or renal function; (iv) checking for appropriate baseline laboratory results, such as platelet count and international normalized ratio for patients receiving anticoagulants; (v) computing drug–laboratory interactions, such as alerting the prescriber to a low potassium concentration when digoxin is being prescribed; and (vi) updating the prescriber with the latest drug information, such as the need to avoid rofecoxib after it had been withdrawn by the manufacturer.