Assessing life expectancy for voluntary assisted dying may prove challenging

25 July 2022
A challenging task for doctors
Doctors determining a person's eligibility for voluntary assisted dying must assess life expectancy which is an 'inherently uncertain and imprecise' task made more difficult by inconsistent wording across state legislation, according to University of Sydney experts.

New South Wales recently became the final Australian state to legalise voluntary assisted dying (VAD) meaning VAD will commence in all states in the next 18 months.

In a perspective piece published today in the Medical Journal of Australia, authors from the University of Sydney’s NHMRC Clinical Trials Centre discuss potential challenges doctors face in determining eligibility based on life expectancy requirements.

“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,” said lead author Dr Sharon Nahm, a medical oncologist and PhD candidate at the University of Sydney’s NHMRC Clinical Trials Centre.

State-based life expectancy eligibility requirements

  • 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.

Among the authors' concerns are terms like ‘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 percent or higher. They compare this to ‘expected to die within six months’ which appears to imply a higher degree of belief.

Dr Nahm said 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 team previously conducted research on the accuracy of oncologists’ estimates of life expectancy for patients with advanced cancer participating in clinical trials. They showed that most patients with an expected survival time of less than six months died within six months.

However, they point 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,” the team writes.

The researchers emphasise that they are not calling for eligibility to be broadened or narrowed but suggest how legislation could be improved by having clearer definitions and phrases that better correspond with how prognoses are formulated.

Best-case, typical and worst-case scenarios

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

The website, 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.

In a questionnaire-based study assessing the tool, recently published in the Journal of Supportive Cancer Care,  91 percent of patients, 96 percent of oncologists, 91 percent of family members and 84 percent of healthcare professionals found it helpful to have life expectancy explained and presented in this way.

Senior research fellow Dr Belinda Kiely believes the website could also be useful for doctors considering eligibility for voluntary assisted dying.

“Most of the VAD legislation for people with advanced cancer require an estimated life expectancy of less than six months. We interpret this to mean a best-case scenario of six months which the website would calculate based on an estimated median survival of two months.”

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

Declaration: The authors had research support from a Conquer Cancer Foundation of the American Society of Clinical Oncology (ASCO) Young Investigator Award; a Cancer Australia and Beyond Blue project grant; and a National Health and Medical Research Council (NHMRC) Australia Program Grant.

Michelle Blowes

Media & PR Adviser (Medicine and Health)

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