As stated previously, most MEs occur with no adverse patient consequence, either because the error was corrected before the drug reached or was taken by the patient or the error did not cause harm. Some MEs result in patient harm. This can range from an extra day of monitoring to permanent bodily damage or death.
MEs that are most likely to cause harm to the patient include incorrect administration of medication (such as inappropriately crushing tablets), delivering drugs through the wrong route (such as intravenous versus intramuscular), and dispensing wrong medications. Insulin, morphine, and heparin are cited as being the agents most frequently involved in errors that result in harm to patients.15
Causes of Medication Errors
As shown in Figure 5–1, medication selection and procurement is the first step in the medication process. MEs in this step include failing to order adequate stock of a medication to meet patient needs, ordering expired or adulterated medication, confusion with substitutions during product shortages and recalls, and ordering the incorrect product, strength, or dilution.
The second step is storage. An ME occurs when any medication that has been stored improperly is subsequently given to a patient. This could include failing to refrigerate a medication or failing to protect a medication from light.
The third step is ordering and transcribing. MEs in ordering occur when the drug selected and/or its dose, frequency, or dosing duration is not appropriate for the patient's disease or physiologic condition. MEs in the transcribing phase include failure to correctly interpret the medication order.
During preparing and dispensing, health professionals must obtain and package the correct drug, dose, or dilution of a product. Medication dispensing errors are defined as any discrepancy between the medication dispensed and the original prescriber's order.
Likewise, an ME in administration is any discrepancy between how the medication is given to the patient and the administration directions from the physician or hospital guidelines.
MEs involved in monitoring and evaluating the effects of medication are defined as not ensuring proper follow-up of the therapeutic effect of a medication or failing to recognize an adverse effect of a medication.
One analysis showed that the most common errors involved prescriptions in which a medication was incorrectly prescribed (18.5%), dosage or quantity was incorrectly interpreted during dispensing (25.5%), and omission (25.6%), in which the prescribed medication was not administered.16 Other studies have slightly different descriptions of the medication ordering process. Bates et al. found 49% of MEs occur during the ordering phase, 11% during the transcribing phase, 14% during the processing (preparing and dispensing) phase, and 26% in the administration phase.17 A majority of errors in the ordering phase are wrong dose or frequency, known drug allergy, and drug–drug interactions.18 Many errors occur in the administration phase, such as wrong dose or incorrect drug administration technique.18
MEs are preventable. ADEs are preventable if they result from an error. In one analysis, Leape et al. found two-thirds of ADEs to be preventable, with an incidence of error due to provider negligence at around 40%. This same study categorizes errors as diagnostic, treatment, preventive, or other.18 The key is in finding the appropriate system or process at the correct step in medication distribution in an attempt to completely alleviate the risk of error.
Preventing Medication Errors
MEs occur for a number of reasons, including the following:
- Ambiguous strength designation on labels or in packaging
- Drug product nomenclature (look-alike or sound-alike names, use of lettered or numbered prefixes and suffixes in drug names)
- Equipment failure or malfunction
- Illegible handwriting
- Improper transcription
- Inaccurate dosage calculation
- Inadequately trained personnel
- Inappropriate abbreviations used in prescribing
- Labeling errors
- Excessive workload
- Lapses in individual performance
- Medication unavailable
It is important to understand that it is human nature to make mistakes. Furthermore, medication-use systems are extremely complex. Therefore, it is vital to create systems with built in safeguards in order to reduce risk and promote safe use of medications. Systems for ordering, dispensing, and administering medications should be designed to minimize error.
Errors can occur at any step in the medication-use process. For each type of error, it is important to determine the root cause, or main reason, for the error. After researching the error and determining its root cause, a tracking system for MEs should be created. Multiple examples of tracking systems are available; errors may be grouped by the type of error or the extent of patient harm.
To design safer medication delivery systems, data must be collected, analyzed, and trended. MEs can be classified by the type of technical error that occurred. The ASHP Guidelines on Preventing Medication Errors in Hospitals classifies errors as shown in Table 5–2. System failures teach health professionals a tremendous amount about the weaknesses inherent in today's complex medical delivery processes. Once tracking systems are in place for MEs and ADEs, processes and systems can be put in place to prevent errors. This may require an upgrade to the current computer program, an upgrade to that software, or an entirely new system. It may mean separating look-alike, sound-alike medications. It may mean creating preprinted orders based on guidelines to prevent inappropriate drug, dose, or monitoring. Training of staff may be required, and monitoring and follow-up is often needed.
TABLE 5-2 Types of Medication Errors |Favorite Table|Download (.pdf)
TABLE 5-2 Types of Medication Errors
|Type of Errora||Examples|
|Prescribing error||Incorrect drug selection (based on indications, contraindications, known allergies, existing drug therapy, or other factors), dose, dosage form, quantity, route, concentration, rate of administration, or instructions for use of a drug product ordered or authorized by physician (or other legitimate prescriber); illegible prescriptions or medication orders that lead to errors that reach the patient.|
|Omission errorb||Failure to administer an ordered dose to a patient before the next scheduled dose.|
|Wrong time error||Administration of medication outside a predefined time interval from its scheduled administration time (this interval should be established by each individual healthcare facility).|
|Unauthorized drug error c||Administration of medication not authorized by a legitimate prescriber for the patient.|
|Improper dose errord||Administration of a dose that is greater than or less than the amount ordered by the prescriber or administration of duplicate doses to the patient (i.e., one or more dosage units in addition to those that were ordered).|
|Wrong dosage-form error e||Administration of a drug product in a different dosage form than ordered by the prescriber.|
|Wrong drug-preparation error f||Drug product incorrectly formulated or manipulated before administration.|
|Wrong administration-technique errorg||Inappropriate procedure or improper technique in the administration of a drug.|
|Deteriorated drug error h||Administration of a drug that has expired or for which the physical or chemical dosage-form integrity has been compromised.|
|Monitoring error||Failure to review a prescribed regimen for appropriateness and detection of problems, or failure to use appropriate clinical or laboratory data for adequate assessment of patient response to prescribed therapy.|
|Adherence error||Inappropriate patient behavior regarding adherence to a prescribed medication regimen.|
|Other medication error||Any medication error that does not fall into one of above redefined categories.|
It is important to remember the significance of MEs and ADEs on patients and the healthcare system. The cost of improving systems and training is negligible compared with the value of lives saved.