Reader in Clinical Pharmacology, Department of Primary Health Care, Rosemary Rue Building, Old Road Campus, Headington, Oxford OX3 7LF
A medication error is defined as “a failure in the treatment process that leads to, or has the potential to lead to, harm to the patient” . The “treatment process” starts after the decision is made to adopt treatment for symptoms or their causes, or to investigate or prevent disease or physiological changes. It therefore involves not only therapeutic drugs but also, for instance, oral contraceptives, hormones used in replacement therapy, and radiographic contrast media. The treatment process includes the prescribing, transcribing, manufacturing or compounding,
dispensing, and administration of a drug. It also includes the monitoring of therapy, because faulty monitoring can lead to a failure to alter therapy when required, or to an erroneous alteration. Note that the definition does not specify who makes the error—it could be a doctor, a nurse, a pharmacist, a carer, the patient, or another. Nor does it specify who is responsible for preventing errors—everybody involved in the treatment process is responsible for their part of the process.
The term “failure” in the definition implies that certain standards should be set, against which failure can be judged. All those who deal with medicines should establish or be familiar with such standards. They should institute or observe measures to ensure that failure to meet the standards does not occur or is unlikely.
Frequency Here are just two examples of error frequencies in different parts of the treatment process. In a UK hospital study of 36,200 medication orders, a prescribing error was identified in 1.5% and most (54%) were associated with the choice of dose; errors were potentially serious in 0.4% . In a US study 1.7% of prescriptions dispensed from community pharmacies contained errors . Since about 3 billion prescriptions are dispensed each year in the USA, about 50 million would contain errors. Of those, about 0.1% were thought to be clinically important, giving an annual incidence of such errors of about 50,000. Wrong label information and instructions were the most common types of errors.
Types of error and prevention There are four broad types of medication errors .
- Errors that occur through lack of knowledge—for example, giving penicillin, without having established whether the patient is allergic. These types of errors should be avoidable by being well informed about the drug being prescribed and the patient to whom it is being given. Computerized prescribing systems and cross-checking by others (for example, pharmacists and nurses) can help to intercept such errors. Education of prescribers is important.
- Errors that occur because a bad rule is used or a good rule is wrongly applied—for example, injecting diclofenac into the lateral thigh rather than the buttock. Establishing proper rules and educating prescribers about them will help to avoid these types of error, as will computerized prescribing systems.
- Errors that occur through wrong actions (slips)—for example, picking a bottle containing chlorpromazine from the pharmacy shelf when intending to take one containing chlorpropamide. These can be minimized by creating conditions in which they are unlikely (for example, by avoiding distractions, by labelling medicines clearly, and by using identifiers, such as bar-codes); cross-checking will also help. A subset of this type of error is the technical error—for example, putting the wrong amount of potassium chloride into an infusion bottle. This type of error can be prevented by the use of checklists, fail-safe systems, and computerized reminders.
- Errors that occur through faulty memory (lapses)—for example, giving penicillin, knowing the patient to be allergic, but forgetting. These are hard to avoid; they can be intercepted by computerized prescribing systems and by cross-checking.
Other methods of preventing errors include the establishment of a blame-free, non-punitive environment, encouraging reporting of errors, including near-misses, using error reports to identify areas of likeliest occurrence, and simplifying and standardizing the steps in the treatment process.
We all make errors from time to time. There are many sources of medication errors and different ways of avoiding them, as listed above. However, one must start by being aware that error is possible. Many prescribers do not believe themselves to be capable of making errors, but they are wrong. They should recognize the possibility and take steps to minimize the risks.
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