Prescription Errors with or without CPOE

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Review of Nicolas A. Thireos's article, Prescription Errors with or without CPOE.

In 1999 the Institute of Medicine (IOM) issued a report stating that every year in this country 48,000 to 96,000 deaths occur due to medical errors, the majority of which are medication or prescription errors. This began a rush of activities aiming at reducing and ultimately eliminating medical errors. With the expectation that Information Technology (IT) can play a major role in medical error elimination, software developers in collaboration with clinicians stepped up their efforts in producing computerized systems to be used in patient care.

Prescription Errors with or without CPOE

Clinical software with a variety of functionalities had already been in use, but the concept of the Electronic Health Record (EHR) became the new focus of these efforts. By switching from the paper-based patient chart to the EHR, health care providers would have direct access to a patient’s complete, accurate, and up-to-date record at the point of care, and they would significantly reduce the number of medical errors. There is now a large number of clinical information systems based on the Electronic Health Record, and the most important of these include Computerized Physician Order Entry (CPOE), as well as clinical decision support (CDS).

As would be expected, there have been many studies of the use of various EHR systems with or without CPOE, attempting to establish the effect they have on the reduction of prescription errors. The majority of CPOE studies show a significant reduction in these errors. Some, however, show that CPOE may fail to eliminate important errors and in fact may introduce new ones. It is difficult to compare the various studies because they define or categorized prescription errors in different ways. The aim of this paper is to identify the most common prescription errors that clinicians are concerned about, as well as some of the ways these errors are grouped or categorized.

A definition of “prescription error” should be a good place to start. Researchers Dean B, Barber N, and Schachter M [1] present the following definition: “A clinically meaningful prescription error occurs when, as a result of a prescribing decision or prescription writing process, there is an unintentional significant (1) reduction in the probability of treatment being timely and effective or (2) increase in the risk of harm when compared with generally accepted practice”. This definition was developed by researchers Dean B, et al [1] in collaboration with a panel of 30 experts who were surveyed in the United Kingdom. This report grouped prescription errors into “errors in decision making” and “errors in prescription writing”. Furthermore, the first group was further subdivided into “inappropriate prescriptions” and “pharmaceutical issues”. The second group was further subdivided into errors due to “failure to communicate essential information” and “transcription errors”. Here are the errors that were listed under these groupings and sub-groupings:

Errors in Decision Making

  1. Prescription inappropriate for patient
    1. Drug prescribed is contraindicated due to a co-existing clinical condition
    2. Patient has clinically significant allergy to drug prescribed
    3. Potential drug-to-drug interaction
    4. Drug dose inappropriate for patient’s renal function
    5. Drug dose below or above that recommended for patient’s clinical condition
    6. Drug dose giving serum levels significantly above or below therapeutic range
    7. Not altering dose when serum levels are outside therapeutic range
    8. Continuing a drug after adverse drug reaction
    9. Prescribing two drugs instead of one for same condition
    10. Drug not indicated for patient

  1. Pharmaceutical Issues
    1. A drug for intravenous infusion in an incompatible diluent
    2. A drug in a greater concentration than recommended for peripheral administration

Errors in Prescription Writing

  1. Failure to communicate essential information:
    1. Wrong drug, dose, or route
    2. Illegible writing
    3. Using drug abbreviations or non-standard terminology
    4. Ambiguous order
    5. Omission of route of administration
    6. Not specifying duration of intermittent intravenous infusion
    7. Omission of prescriber’s signature
  2. Transcription Errors
    1. Upon admission to hospital failure to prescribe a drug the patient was already on
    2. Upon admission to hospital continuing a GP’s prescribing error
    3. Incorrect transcribing when rewriting a patient’s drug chart
    4. Ordering “milligrams” while intending “micrograms”
    5. Upon admission to hospital unintentionally changing a pre-admission prescription
    6. At discharge writing a prescription unintentionally different from inpatient chart

Another study by Rob Shulman, et al. [2] categorizes prescription errors as minor, moderate, and major. They are defined as follows:

Minor errors

    1. They cause an increase in patient monitoring
    2. They do not affect vital signs
    3. They cause no harm to the patient
  1. Moderate errors:
    1. They cause an increase in patient monitoring
    2. They affect a change in vital signs
    3. They cause no harm to the patient
  2. Major Errors:
    1. They create a need for treatment or an increase in length of hospital stay
    2. They may cause permanent harm or death to the patient


In this same study, the researchers list the following advantages of CPOE without CDS over paper prescribing: “standardization, full audit trail, legibility, use of approved names, specification of key data fields such as route of administration, storage and recall of records.” Medical facilities with CPOE and also clinical decision support (CDS) can practice evidence based medicine and improve the quality of care. Specifically, they can a) prevent prescription of a known allergenic drug, b) avoid a toxic drug dose, c) flag drug-to-drug interactions, d) force compliance with hospital protocols, and e) prevent prescription of some drug.

The study showed that, although CPOE, is generally recognized as very beneficial to drug reduction, it “appeared to be associated with a high number of dosing errors, omission of the required drug and the prescriber’s name.” Three serious errors made with CPOE were actually intercepted by a nurse or pharmacist, but could have caused great harm or death to the patient. In the first one of these, a potentially fatal dose was selected from a pull-down menu. In the second case, instead of the proper drug, a similarly sounding drug was selected. It would have caused an adverse drug event (ADE). In the third case, the correct IV dose was selected, but the required repeat instructions were not included. These three errors are attributed to CPOE because it was unable to stop them.

A third study, conducted by Potts AL, Barr FE, Gregory DF, Wright L, and Patel NR [3] evaluated the impact of CPOE on the frequency of medication errors in a pediatric critical care unit. These investigators classified errors as potential Adverse Drug Events (ADE), Medication Prescription Errors (MPE), and rule violations (RV). They found that the frequency of all three classes was significantly reduced by the use of CPOE.

As can be seen from these and many other studies, medication or prescription errors are a major cause of concern around the world. Whether we address the types of errors, the severity, their causes, their effects on the patient’s healing process, whether they were discovered before they affected the patient or after with an adverse Drug Effect (ADE), one thing is certain; they must be eliminated! Let us hope that CPOE and related systems will be perfected and used universally, so that medication or prescription errors can become a thing of the past! If we can land on the moon with our technology, why can’t we use it to keep us safe from our errors?


  1. Dean B, Barber N, Schachter M. What is a prescribing error? Qual Health Care. 2000;9:232-237. Doi: 10.1136/qhc.9.4.232.
  2. Shulman R, Singer M, Goldstone J, Bellingan G. Medication errors: a prospective cohort study of hand-written and computerized physician order entry in the ICU. Crit Care. 2005;R516-R521. Doi: 10.1186/cc3793.
  3. Potts AL, Barr FE, Gregory DF, Wright L, Patel NR. Computerized physician order entry and medication errors in a pediatric critical care unit. Pediatrics. 2004; 113:59-63. doi:10.1542/peds.113.1.59.
  4. Koppel R. What do we know about medication errors made via a CPOE system versus those made via handwritten orders? Crit Care. 2005; 9(5):427-428. Doi: 10.1186/cc3804.