Editor—Thornton et al argue that women need better information on breast screening.1 A great deal of evidence is available on how risk should be presented to facilitate understanding.2
Absolute risks should be given more prominence than relative risks. The effects of the decision over the individual's lifetime should be presented rather than the effects in the next few years.
The way information is framed also influences the decisions people reach. Reductions in losses (such as “screening decreases mortality from 6% to 4%”) are more persuasive than increases in gains (such as “screening increases survival from 94% to 96%”).
Unless our aim is to manipulate, the influence of framing should be minimised by presenting risks of both gains (survival) and losses (mortality). People tend to understand data more easily if they are presented in the form of integers (3 in 10 people) rather than probabilities (30% of people). Any attempt to present risk information to women should make use of decision aids.3
Current breast cancer information leaflets do not contain information on absolute reduction in mortality or absolute risk of further investigation over the course of a screening career and do not use any decision aids.4 Decision aids for breast cancer screening have been published that meet at least some of these requirements.5 I hope they will be found in future leaflets.
Competing interests: None declared.
References
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- 4.Health Promotion England in association with the NHS Cancer Screening Programmes, with advice and support from the Cancer Research Campaign Primary Care Education Research Group. Breast screening the facts. Health Promotion England, 2001.
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