Presentation of risk influences consent
The way in which a treatment's effect is described, even when descriptions are quantitatively equal, influences patients' willingness to take that treatment, according to research published last week (Annals
of Internal Medicine 2007;146:848).
In a cross-sectional survey of 2,754 healthy people, researchers presented
scenarios regarding a hypothetical drug therapy to reduce the risk of
heart attacks or hip fractures. Participants were randomly assigned to
a scenario with one of three outcomes after five years of treatment.
For a heart attack, treatment effect was presented as postponement by
two months for all patients, postponement by eight months for 25 per
cent of patients or a number needed to treat (NNT) of 13 patients to
prevent one heart attack. For hip fracture, treatment effect was presented
as postponement by 16 days for all patients, postponement by 16 months
for 3 per cent of patients, or an NNT of 57 patients to prevent one fracture.
The benefits described were equivalent and calculated from clinical trials.
The researchers found that in both groups, the proportion of respondents
who consented to therapy was highest when the effect was presented in
NNT and lowest when it was presented as a short-term postponement of
the outcome for all patients (P<0.001 for both groups). Many respondents
reported difficulty in understanding the description of treatment benefit
regardless of how it was presented, and these people were less likely
to consent to therapy, say the researchers.
The researchers acknowledge that the study has limitations but emphasise
that the different formats evoked different choices when lay people responded
to hypothetical scenarios. “Perhaps the same is true in real life,” they
say.
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