How are non-numerical prognostic statements interpreted and are they subject to positive bias?

Frank, clear communication with family members of terminally ill or incapacitated patients has important implications for well-being, satisfaction with care and sound decision-making | BMJ Supportive & Palliative Care

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Objectives: Numerical prognostic statements, particularly more negative ones, have been found to be interpreted in a positively biased manner. Less precise non-numerical statements, preferred by physicians, and particularly statements using threatening terms (dying vs surviving) may be even more subject to such biases.

Methods: Participants (N=200) read non-numerical prognostic statements framed in terms of dying or surviving and indicated their interpretation of likelihood of survival.

Results: Even the most extreme statements were not interpreted to indicate 100% likelihood of surviving or dying, (eg, they will definitely survive, 92.77%). The poorness of prognoses was associated with more optimistically biased interpretations but this was not, however, affected by the wording of the prognoses in terms of dying versus surviving.

Conclusions: The findings illuminate the ways in which commonly used non-numeric language may be understood in numeric terms during prognostic discussions and provide further evidence of recipients’ propensity for positive bias.

Full reference: Moyer, A. et al. (2017) How are non-numerical prognostic statements interpreted and are they subject to positive bias?