Claire Wratten looks at MDU data on claims relating to prescribing errors and asks what doctors can do to minimise the risks.

Prescription errors are one of the most common subjects for a claim notified to the MDU. Although generally damages payments for these claims are not particularly high, the error can nevertheless cause significant anxiety for both the patient and the prescriber. And even though the majority of prescription error claims notified to the MDU don't result in ongoing harm to the patient, in occasional cases the results can be catastrophic.

Historically, the source of an error might have been the prescriber's handwriting. But with the advent of electronic prescribing, the error more commonly relates to accidentally clicking on the wrong drug or wrong dose from a drop down menu. This can then be compounded if the medication is put on repeat prescription, and so several prescriptions may be issued before the error is picked up. The patient may suffer not only side effects from the wrong medication, but also problems due to a lack of the intended medication.

Cases and claims

An analysis was carried out of all closed cases between 2011 and 2015 which related to prescription errors. There were a total of 217 cases closed over this five year period, and of these, 137 (63%) were successfully defended. This is slightly lower than the MDU's rate of successfully defending claims overall, which is almost 75% over the last 10 years, and reflects the fact that prescription errors can be hard to defend in terms of breach of duty. It may however be possible to defend a case on the basis that although a prescription error was made, no harm was caused to the patient.

Damages paid to patients ranged between from £900 to almost £2 million. The latter concerned hypoxic brain injury following cardiac arrest due to excessive morphine. However, more than half of the claims resulted in damages payments under £15 000, and only 6% in a payment over £100,000, the majority of which were due to excessive prescribing of sedating analgesics.

The majority of cases involved GPs, but 5% of claims were from members in private practice.

Types of drugs

Over 50 different drugs or drug types were involved, and there were also claims related to devices and method of drug delivery (prescribing eye drops rather than ear drops, for example). The most common cause of drug errors was analgesics other than non-steroids (mainly opiates), followed by NSAIDs. The other most frequently involved drugs were penicillins, then other antibiotics, followed by anti-epileptics and then anti-depressants. The chart below illustrates the 10 most common types of drug involved in prescription error claims:

Graph for prescription claims

The most common drug-related errors were prescribing a drug to a patient with a known allergy, in particular penicillins; prescribing the wrong drug (due to them having similar names, for example, such as mefloquine and malarone); or prescribing the wrong dose of the drug (for example a twice weekly drug being prescribed daily).

Other problems included failing to consider drug interactions, resulting in side-effects. Some claims were brought because patients had developed addictions to medications, and there were also claims due to recognised side-effects of a medication, such as renal impairment due to NSAIDs, or respiratory depression due to opiates. Claims involving warfarin related to problems with INR measurement, as well as both bleeding and thrombosis.

Case report

A patient with hypertension was prescribed NSAIDs for possible gout. This resulted in improvement in his symptoms, and the NSAIDs were put on a repeat prescription, which continued for four years. During this time, he remained on anti-hypertensives and his blood pressure was well controlled, but his renal function was not checked.

When the patient's renal function was ultimately checked, his serum creatinine was 147µmol/L. A letter was sent inviting the patient to make an appointment for review, but no appointment was made and repeat prescriptions continued to be issued for both the NSAIDs and the anti-hypertensives.

Two years later, renal function was measured again and the serum creatinine had risen to 180µmol/L, and the calculated GFR was 36ml/min. Renal function was rechecked three months later and was unchanged. The patient remained on NSAIDs and the renal function was not repeated for another three years, by which time the patient had a GFR of below 20ml/min. At this point, the NSAIDs were stopped and a referral made to the nephrology clinic, but unfortunately renal function continued to decline and the patient required renal replacement therapy.

A Letter of Claim was received, alleging that there was a failure to monitor renal function despite long term prescriptions of NSAIDS to a hypertensive patient, and that once renal impairment was demonstrated there was a failure to stop the NSAIDS, and a failure to measure renal function regularly. It was alleged that had this occurred, end stage renal failure would have been avoided.

The MDU instructed independent GP and nephrology experts. The GP expert advised that renal function should have been measured more frequently, and once renal impairment was diagnosed, serious consideration given to stopping the NSAIDs and prescribing alternative analgesics.

The nephrology expert advised that the long-term prescription of NSAIDs made a significant contribution to the claimant's renal impairment and end-stage renal failure. In the light of this expert advice, and with the agreement of the MDU GP involved, the claim was therefore settled.

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The steps that can be taken to try and reduce prescription errors may seem obvious, but the number of claims that the MDU is notified of suggests that despite care being taken, checks are not always being made. These include checking for known drug allergies and drug interactions, and taking care to prescribe the intended drug, at the correct dose and via the correct delivery method.

All drugs have side effects and it is important to warn patients about the common and serious ones, and to re-evaluate the need for a particular drug if any side-effects do occur. This re-evaluation may also be needed if the clinical situation changes, such as if a patient on NSAIDs develops renal impairment, or pregnancy in a patient taking drugs which may then be contra-indicated.

If you need advice about a possible prescribing error, please contact our medico-legal team.

This page was correct at publication on 27/07/2016. Any guidance is intended as general guidance for members only. If you are a member and need specific advice relating to your own circumstances, please contact one of our advisers.