Why do interns make prescribing errors? A qualitative study

Adverse events caused by medication have been estimated to harm 1% to 2% of patients admitted to hospitals in the United States, United Kingdom and Australia.1-3 Most incidents that result in harm to patients originate in the prescribing process.4 Human error is a frequent factor.5

The intern year is a time for consolidating medical school education through continued learning and acquisition of knowledge and skills under direct supervision. More prescribing errors occur in the first year after graduation than in all other years.6 In an American study, 45% of interns reported having made at least one clinical error; 29% were prescribing errors, of which 15% were fatal.7

Although a particular action or omission may be the immediate cause of an incident (described as an active failure or error),8 closer analysis usually reveals a series of events and departures from safe practice, known as an error chain.5 The notion of a single root cause, although widespread, is an oversimplification.8,9 A structured process, which uses human psychology methods, is available for analysis of errors.8,10 This analysis method considers the individual’s working environment, including the team and the organisation.

In this prospective qualitative study, we aimed to identify and analyse the factors underlying prescribing errors made by interns in order to identify multifaceted interventions that would reduce the risk of similar events recurring.

Between February and June 2004, pharmacists at a 700-bed teaching hospital prospectively reported potentially harmful errors by interns. The following definition of an error was used:

All prescribing was handwritten on an inpatient medication chart. Discharge prescriptions were generated from a triplicate carbon copy system. All 34 interns at the hospital were informed that the study was taking place, that the goal was to introduce safety-improvement strategies, and that deidentified errors would be reviewed by the medication safety team and used subsequently in prescribing training for medical students. Interns rotated among clinical units every 10 weeks. Following local ethics approval, all interns interviewed gave signed consent. Only interns who were involved in incidents and contactable within 72 hours of the incident were interviewed, to ensure adequate recall of events.

Semistructured face-to-face interviews incorporating a questionnaire were conducted to assess the causes of the prescribing error. The process was adapted, with permission, from the methods of Vincent et al8 and Dean et al.12 Interviews took between 15 and 115 minutes (average, 44 minutes) and used the process outlined in Box 1.

As interns were reluctant to be taped, a detailed deidentified transcript was made and then reviewed by the intern.

We (a senior physician and two senior pharmacists) analysed and coded the transcripts independently, using Vincent et al’s framework of error-producing factors.8 Consensus was achieved through discussion.

Errors were classified as either “new prescribing” or “represcribing.” New prescribing involved a decision to start, stop or change a drug, or a drug’s form, route or dose. Represcribing was any continuing therapy, and included prescriptions written when patients were admitted to hospital, transferred or discharged.

We identified latent factors underlying the errors, by thematic analysis.

Forty-seven errors were reported, of which 21, involving 14 interns, were analysed. One intern was interviewed about four incidents, four about two and nine about one each.

Twenty-six errors were not analysed because prescribers were unable to be identified (8), declined to be interviewed (7; with 3 having been interviewed before), or did not attend (3), or the errors were reported more than 72 hours after the event (8).

The 21 errors that were analysed are described in Box 2. They occurred on admission to hospital (3), during the inpatient stay (9), and on discharge (9). Antithrombotic and antibiotic drugs accounted for half the errors.

In 10 of the incidents where prescribing was directed by a senior doctor, the intern determined the route, form, dose, frequency or duration of the drug and had to consider the previous adverse drug reactions or renal impairment. In only one case of new prescribing was the intern solely responsible for the decision to initiate a medication. In three cases, the intern was prescribing for another doctor’s patient, two when on call.

In 13 incidents, the interns had previously prescribed a drug, but they often mentioned that they did not know the dose. In seven cases, they admitted to having made the same or a similar error previously.

All errors were associated with a varying combination of environment, team, individual, task, patient and latent factors, in a system with porous defences. We found that, while almost all errors were influenced by environment factors, factors associated with new-prescribing errors and represcribing errors were different, which was not the case in previous studies of error causation.1,12,13

New-prescribing errors involved inexperienced interns, who were tired, hungry, and distracted, prescribing for patients with complex disorders. Team factors, in particular lack of supervision, were also more frequently associated with new-prescribing errors. Represcribing errors were often related to the task, including the design and location of the medication chart. Therefore, the view that a single intervention in isolation will prevent most prescribing errors is simplistic.14

Our results confirm those of others that improving drug knowledge may decrease the risks of new-prescribing errors.14-18 However, a lack of drug knowledge was a partial cause of only one represcribing incident. Interns need to be able to apply drug knowledge to allow them to tailor therapy to an individual patient. Safe-prescribing skills and awareness of medication errors is required by all members of the health care team,19,20 and should be a core component of undergraduate and postgraduate training programs, as outlined in the new curriculum framework for junior doctors.21 Practical safe-medication practice training that improves the safety of medical students’ prescribing should be a core component of prescribing education.14,20

The primary focus of the intern year is to produce competent, independent practitioners through an apprenticeship, with training in a range of supervised posts.22 In this study, there was an assumption by interns that senior staff would check their prescriptions. Often, this did not happen. Our findings reinforce those from the UK, where a culture exists in which new prescribing is seen by senior and junior staff as focused on drug selection, and represcribing as a low-risk chore for which training or supervision is not required.12,17

The complexity of prescribing is not appreciated by the novice, and the novice’s lack of deeper understanding does not appear to be understood and supported by supervisors. Interns often have insufficient knowledge to appreciate when they need to seek advice. Deference to a hierarchical structure is a well recognised risk in all complex teams, and junior staff need to have the skills and feel able to confirm and clarify directions.23

Supervision should take account of all prescribing risk factors, including the patient’s complexity, the intern’s competence, the specific medications being prescribed and the availability of guidelines. This must be within a culture in which prescribing is seen as an important, high-risk intervention. Institutions must develop an environment in which prescribing errors can be constructively discussed and analysed, and learning from errors should occur at an individual, team and organisation level.12

Electronic prescribing with decision support offers a partial solution,24,25 but an effective system is not currently widely available in Australia.26 Standardised medication charts and systems incorporating decision support and forcing functions have been developed and should be implemented to reduce prescribing errors.27 With a standard chart in place, students can be trained to use one system, and the risks of error due to unfamiliarity with chart design can be reduced.17

Nursing staff provide a critical defence by reviewing medications before administration, but training in safe medication is also required.28 Pharmacists detect errors and improve the safety of prescribing.29 Their role of reviewing prescriptions and contributing to prescribing decisions must be further developed.13

Guidelines and drug information must be readily available to prescribers. The Australian medicines handbook has reworded dosing instructions in response to the findings of this study, but similar risks remain unless guidelines and protocols are evaluated for such risks.

Changes to workload and staffing levels remain a risk for all health care professionals. Strategies such as split shifts need to be considered, but must ensure clinical handover of patients between doctors. The environments in which interns prescribe must not be distracting. The location of medication charts, ideally at the bedside, has already been addressed at the study site.

Our study, using a sample of convenience, cannot estimate the incidence of errors. Also, there may have been a degree of social desirability in responses, and the 26 incidents not investigated may have provided additional or different perspectives. However, we believe our findings are representative, and have raised important issues, which may lead to significant interventions.

The prescribing errors identified have happened before and will happen again unless changes at many levels are made. Prescribing skills and awareness of medication errors must be developed through training. Standardised medication charts reduce errors and are being implemented across Australia, and guidelines should be redesigned and readily available. A cultural shift, in which prescribing is seen as important, must occur, with continual senior review and tailored supervision of interns in an atmosphere that encourages clarification and learning.

3 Incident analysis framework*

AMH = Australian medicines handbook. * Adapted from Reason’s model of accident causation,5 with permission.