GP prescribed wrong lithium dose after failing to double check patient’s discharge summary: inquest

The GP then failed to act when the patient presented with signs of lithium toxicity, the coroner found.

A GP prescribed the wrong lithium dose to a patient despite receiving a hospital discharge summary and reports with the correct, lower dose, an inquest has heard. 

Andrew Stubbs died three months later from dialysis disequilibrium syndrome (DDS), a rare complication of dialysis to treat severe lithium toxicity and kidney failure. 

NSW coroner’s court was told that the 32-year-old’s schizoaffective disorder had been successfully treated with lithium since 2017. 

He was admitted to Campbelltown Hospital for treatment in 2019 and then discharged with a plan to reduce his dose of 1250mg per dose down to 1000mg.

This was subsequently done while he was under the care of a community mental health team. 

In April 2020, Mr Stubbs was then discharged into the care of his GP with whom he had consulted over the previous four years.

“Andrew told [the GP] that he was on a dose of 500mg lithium in the morning, and 750mg lithium at night (1250mg per day),” NSW Deputy State Coroner David O’Neil wrote in his findings.

“[The doctor] considered Andrew to be a rational historian, who was proactive about his own health. He therefore felt it was reasonable to accept Andrew’s account at the time.

“He recorded the dose in Andrew’s medical record.”

The GP said he had developed a good rapport with Mr Stubbs over the years, however, he had only been given limited guidance on prescribing lithium and only recalled prescribing the drug to two or three other patients.

However, as part of the clinical handover, the GP was sent four documents, including a discharge summary before his conversation with Mr Stubbs, listing the correct dose.

“In evidence, he stated it had not ‘clicked’ that the dose on these documents was different, and he had overlooked it,” the coroner said.

“He accepted he had not ‘double or triple-checked’ the dose and that he should have done so.”

Blood tests taken the following month showed Mr Stubbs’ lithium levels were above therapeutic levels.

But repeat blood tests were not arranged, the coroner said.

Mr Stubbs was eventually taken to Bowral Hospital which found he had a toxic/fatal level of lithium (4.5mmol/L)

On transfer to Campbelltown Hospital, he was initially administered continuous venous-venous haemodiafiltration in the ICU, before being transferred to the renal unit for intermittent haemodialysis. 

Both carried risks of DDS.

By the following evening, Mr Stubbs was complaining of severe headaches, confusion, drowsiness and vomiting, at one stage asking nursing staff to “just let me die”.

After he lost consciousness a few hours later, a CT scan and then an angiogram of Mr Stubbs’ brain showed his condition was non-survivable, with diffuse cerebral oedema, consistent with raised intracranial pressure, and herniation of the cerebellar tonsils.

In findings published last month, the coroner rejected the GP’s declaration he’d had limited guidance for prescribing lithium.

“As [he] had accepted the responsibility of prescribing lithium it was incumbent upon him to seek support and advice as needed, to prescribe it safely,” he wrote.

But he said the GP had “genuine concern” for Mr Stubbs.

“He expressed regret for the shortfalls in his care. He stated that he has changed his practice; in the future, if he has a patient on lithium, he will refer to a psychiatrist for direction on how often to monitor lithium levels, and how to interpret the results.”

The coroner was critical of the care Mr Stubbs received at the hospital.

His DDS symptoms were initially attributed to his lithium toxicity and intermittent haemodialysis should have been ceased when he showed signs of deterioration, he said.

But he noted that the hospital had never dealt with such a severe case of DDS before.

In addition, staff were under significant pressure due to high workloads.

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More information: Coroner’s Court of NSW; 11 August 2023