Cancer care

Oncologist website can help assess patient life expectancy for VAD

Thursday, 28 Jul 2022

Australian oncologists have developed a website to help cancer clinicians navigate the confusing and inconsistent eligibility criteria for voluntary assisted dying  (VAD) programs for people with terminal illness.

A group of University of Sydney clinicians say that with all states now implementing VAD programs, doctors are being asked to do the impossible because assessing life expectancy is an ‘inherently uncertain and imprecise’ task.

In a perspective piece in the MJA, they say that while most states’ legislation for VAD schemes are based on a six month life expectancy, the criteria are based on legal concepts rather than clinical realities.

“Prognosis is difficult and by its very nature uncertain. However, differences across states in the wording of current legislation could make determining eligibility even more difficult for doctors,” says lead author Dr Sharon Nahm, a medical oncologist and PhD candidate at the University of Sydney’s NHMRC Clinical Trials Centre.

Among the authors’ concerns are terms such as ‘on the balance of probabilities,’ a legal concept typically applied to the burden of proof in civil claims and taken to mean ‘more probable than not’, therefore suggesting a probability of 51% or higher of dying within six months.

They compare this to wording such as ‘expected to die within six months’ which might imply a higher probability of 70%, 80% or 90% of dying.

Dr Nahm said that regardless of terminology differences, the VAD legislation in its current form is asking doctors to predict an unspecified probability of a patient dying within a particular period.

“This is a very different question to what doctors typically get from their patients, which is ‘How long have I got?’” she said.

The Sydney University team said they were not advocating that the eligibility criteria be broadened or narrowed, but rather that legislation should be improved by including clearer definitions and explanations of phrases using probabilistic terminology that corresponds with how prognoses are best formulated and communicated.

With this aim, the team has developed a website to assist oncologists with communicating prognoses to patients with advanced cancer.

Three Scenarios for Survival takes an oncologists’ estimate of the likely survival time of their patient (that is, the median survival for a group of similar patients) and calculates best-case, typical and worst-case scenarios for survival. This is presented as a one-page summary that can be discussed with patients and their families.

“The website could be very useful in helping clinicians estimate, understand and explain these different scenarios,” said co-author Professor Martin Stockler, Professor of Oncology and Clinical Epidemiology at the University of Sydney.

An estimated life expectancy of less than six months could be interpreted  to mean a best-case scenario of six months, which the website would calculate based on an estimated median survival of two months, the authors said.

Their previous research on the accuracy of oncologists’ estimates of life expectancy for patients with advanced cancer showed that most patients with an expected survival time of less than six months died within six months.

However, they pointed out that these studies are in people with advanced cancer enrolled in clinical trials, and may not apply to people with other terminal illnesses.

“Doctors are not trained to formulate estimates of expected survival time, or to explain them to patients. We predict that many doctors will find it difficult to answer whether they expect individual patients to die within six months,” they wrote.

State-based life expectancy eligibility requirements for VAD:

  • In Tasmania, a person is eligible if they have a condition that is ‘expected to cause death within six months.’
  • In Victoria and South Australia, it is ‘expected to cause death within weeks or months, not exceeding six months.’
  • In Western Australia and New South Wales it ‘will, on the balance of probabilities, cause death within a period of six months.’
  • In the above states, a longer period (12 months) is allowed for people with a neurodegenerative disease.
  • In Queensland, the condition is ‘expected to cause death within 12 months’, without distinguishing the type of condition.

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