Investigating chemotherapy prescribing errors

The workload in oncology clinics is growing but there is a paucity of doctors and a high prevalence of prescribing errors and these were all factors that prompted researchers at University College Cork to ask whether prescribing of chemotherapy by pharmacists might have beneficial clinical and economic impacts.

In this prospective, comparative study 82 percent of errors were from doctor-prescribed chemotherapy and 23 (18% percent) were from pharmacist-prescribed chemotherapy. In addition, 17.6 percent of doctors’ prescribing errors were classified as having a high probability of causing an ADE compared with zero percent for pharmacists’ prescribing errors.

An economic analysis suggested that the implementation of a pharmacist prescribing service for chemotherapy could be associated with a saving of more than 1.2 million Euro annually.

How investment could help reduce chemotherapy prescribing errors

Chemotherapy prescribing is an “error-prone process”, Ms Nally explains and all chemotherapy prescribing errors have an economic impact. Errors that are intercepted before they reach the patient incur the costs of ‘reworking’ – in this case re-prescribing, re-checking etc. Errors that are not intercepted could damage patients either by under- or over-treating patients.  Ms Nally cites examples of some of the errors classed as ‘severe’ in this study.

She concludes that pharmacist-prescribing results in significantly fewer chemotherapy prescribing errors. It also reduces the risk of adverse drug reactions and patient harm and it has the potential for substantial cost savings.  Most importantly, it improves patient safety and should therefore be considered for implementation in cancer care services on a much wider scale, Ms Nally says.

Shannon Nally is now Aseptic and Cancer Services Pharmacist at Imperial College Healthcare NHS Trust.

The poster: Evaluating the potential clinical and economic impact of chemotherapy prescribing by pharmacists at a university teaching hospital was selected as Best Poster at the EAHP Congress held in Lisbon, Portugal 22-24^th March 2023.

Read and watch the full series on our website or on YouTube.

Of the 124 prescribing errors recorded in this study 17 were classified as ‘severe’ by the independent panel of reviewers.  Examples include:

• One patient who was prescribed weekly paclitaxel while she was waiting for pathology results. When the results arrived, they showed HER2-positive breast cancer for which trastuzumab and pertuzumab should have been prescribed. Failure to prescribe these agents for this patient could have compromised the success of the breast cancer treatment, comments Ms Nally.
• A patient with colon cancer was prescribed a “totally different” regimen that is normally used for pancreatic cancer.
• A patient was prescribed carboplatin 810 mg “but based on their renal function the dose should have been 600 mg – so this is a 35 percent overdose”, says Ms Nally.

Both severity scores and the ‘probability of adverse drug events’ were reported. The probability score indicates the probability of causing an adverse drug reaction (ADE) if the error reached the patient and the severity score indicated how severe an ADE would be if it reached the patient.

The economic evaluation included both labour costs and the costs of an ADE. “We calculated the time it took to correct any error and re-prescribe it because when a prescribing error is made it adds to the workload of both the doctor and the pharmacist. The pharmacists must start correcting the prescription – they realise there’s an error, they must phone up the doctor, communicate it to them, the doctor then in turn must re-prescribe his prescription, it’s sent back to the pharmacist, they recheck it – so this is an extra few steps in the cycle. So, all labour costs associated with that error were calculated”, explains Ms Nally. Only senior doctors (registrar, specialist registrar (SpR) or consultant) are permitted to prescribe, she adds.

The average time to write a prescription was about four minutes for both pharmacists and doctors.  However, doctors often prescribed longer infusion times than pharmacists resulting in avoidable increases in the nurse time required for administration. “The doctors prescribed an additional 835 nursing minutes compared to [an additional] 30 minutes by pharmacists.  To put this into context – a doctor or a pharmacist could have prescribed pembrolizumab [to be administered] over an hour when you can actually give it over 30 minutes. So, these 30 minutes of additional nursing time comes with an extra cost for the nurse, ……. so these prolonged infusion times contribute to prolonged patient stays and reduce the capacity of our day wards”, says Ms Nally.

In order to determine whether the implementation of a pharmacist prescribing service would be beneficial in terms of cost avoidance for the hospital, a cost analysis was performed using the method described by Gallagher and colleagues.  This was based on the assumption that all errors actually reached the patients i.e. that the screening pharmacist failed to identify and intercept the errors.

“So, in terms of cost avoidance to the hospital, a yearly net cost benefit of over 1.2 million Euro and a cost-benefit ratio of nearly 42 Euro was calculated based on the provision of a pharmacist chemotherapy prescribing service”, says Ms Nally.

Why do errors occur?

“No doctor or [prescribing] pharmacist sets out to make errors, they’re all unintentional – it’s human nature. But, as a hospital group and at a management level we need to have systems in place to eradicate and minimize patient harm. We know that medication errors cause a significant amount of injury and preventable harm in health care systems around the world and the World Health Organization (WHO) has reported [that] the cost of medication errors is [about] 42 billion USD annually”, says Ms Nally. In addition, factors including overburdened healthcare systems, polypharmacy, complex patient groups and inexperienced doctors prescribing add to the risks of prescribing. Chemotherapy represents a substantial risk because of a number of factors including patient vulnerability, complex treatment regimens, drugs with narrow therapeutic indices and frequent parenteral administration.  “It makes the prescribing of chemotherapy an error-prone process”, emphasises Ms Nally.

In this study, the doctors were prescribing for patients in the normal way, whereas for the pharmacists involved it was a hypothetical exercise. Moreover, the doctors were unaware that the study was taking place. “Now the normal practice is that their prescriptions are screened by pharmacists – so pharmacists will always check their work regardless of pharmacist prescribing – so the doctors are always conscious that we as pharmacists check their work”, says Ms Nally. “In our hospital, the guidelines are that only senior doctors can prescribe so [the doctors involved] were well-versed, experienced doctors”, she adds.

This study has shown that pharmacist-prescribing and better used of our expert skill set results in significantly fewer chemotherapy prescribing errors than doctors; it minimises workload for healthcare professionals; we reduce the risk of adverse drug reactions and patient harm and it has the potential for substantial cost savings for our hospitals. Most importantly, it improves patient safety and therefore this is ultimately why this initiative ….. should be considered for implementation in cancer care services on a much wider scale , Ms Nally concludes.

Shannon Nally is now Aseptic and Cancer Services Pharmacist at Imperial College Healthcare NHS Trust.

The poster: Evaluating the potential clinical and economic impact of chemotherapy prescribing by pharmacists at a university teaching hospital was selected as Best Poster at the EAHP Congress held in Lisbon, Portugal 22-24^th March 2023.

Read and watch the full series on our website or on YouTube.

View the poster here

Awareness of the growing incidence of cancers combined with high rates of prescribing errors with chemotherapy led researchers at UCC to ask whether prescribing of chemotherapy by pharmacists might have beneficial clinical and economic impacts. Other important driving factors included the “increasingly multi-morbid, aging population [and] a paucity of doctors in our healthcare system”, says Ms Nally.  Chemotherapy prescribing errors represent a potentially serious risk for patients – the consequences of either underdoses or overdoses can be serious.  Moreover, the workload in oncology clinics is making them “increasingly pressurised” and “we need to think of innovative ways to help reduce this pressure while maintaining and enhancing the patient experience”, she adds.

Ms Nally undertook a comparative, prospective study that evaluated the clinical and economic impact that chemotherapy prescribing by pharmacists could have at a university teaching hospital.  In order to do this, the same set of 155 prescriptions was prepared separately by doctors and pharmacists and then compared and presented to a panel of peer reviewers.  “[The members of the] peer review panel were all independent of the study – none of them took part in our study.  Three of them were consultants based in other hospitals [and] three of them were specialised pharmacists who did not take part in the study”, she explains. Prescribing errors were categorised according to the Pharmaceutical Care Network Europe (PCNE) classification scheme for drug related problems (DRPs). The panel of peer reviewers determined the severity ratings for each error and the probability that it would have caused an adverse drug event (ADE) if it had reached the patient. “It’s really important to bear in mind as well that the doctors did not know the study was taking place and the pharmacists were blinded to what the doctors prescribed”, she says.  The prescriptions involved more than1400 medicines, with more or less equal numbers of chemotherapy drugs and supportive therapy. The indications included breast and colon cancers as well as haematological malignancies. The majority (95 percent) of the prescriptions were electronic and only five percent were handwritten.  “Of all the errors that occurred a little over half of them were from the wrong dose being prescribed…. This is where it gets interesting – so a total of 128 prescribing errors were identified from the 310 prescriptions. Of these, 105 (82 percent) were from doctor-prescribed chemotherapy and 23 (18% percent) were from pharmacist-prescribed chemotherapy – and for this figure we got a p-value of less than 0.05,  …. showing that our results were significant”, say Ms Nally. In addition, 17.6 percent of doctors’ prescribing errors were classified as having a high probability of causing an ADE compared with zero percent for pharmacists’ prescribing errors. “Assuming then that the errors were not spotted and that they all reached the patients we derived a net cost-benefit of utilising a pharmacist prescribing service and the savings were over 1.2 million Euro on an annual basis”, she says.

Shannon Nally is now Aseptic and Cancer Services Pharmacist at Imperial College Healthcare NHS Trust.

The poster: Evaluating the potential clinical and economic impact of chemotherapy prescribing by pharmacists at a university teaching hospital was selected as Best Poster at the EAHP Congress held in Lisbon, Portugal 22-24^th March 2023.

Read and watch the full series on our website or on YouTube.