Bodemer Nicolai, Meder Björn, Gigerenzer Gerd
Max Planck Institute for Human Development, Harding Center for Risk Literacy, Berlin, Germany (NB, GG)
Max Planck Institute for Human Development, Center for Adaptive Behavior and Cognition (ABC), Berlin, Germany (NB, BM, GG).
Med Decis Making. 2014 Jul;34(5):615-26. doi: 10.1177/0272989X14526305. Epub 2014 May 6.
Treatment benefits and harms are often communicated as relative risk reductions and increases, which are frequently misunderstood by doctors and patients. One suggestion for improving understanding of such risk information is to also communicate the baseline risk. We investigated 1) whether the presentation format of the baseline risk influences understanding of relative risk changes and 2) the mediating role of people's numeracy skills.
We presented laypeople (N = 1234) with a hypothetical scenario about a treatment that decreased (Experiments 1a, 2a) or increased (Experiments 1b, 2b) the risk of heart disease. Baseline risk was provided as a percentage or a frequency. In a forced-choice paradigm, the participants' task was to judge the risk in the treatment group given the relative risk reduction (or increase) and the baseline risk. Numeracy was assessed using the Lipkus 11-item scale.
Communicating baseline risk in a frequency format facilitated correct understanding of a treatment's benefits and harms, whereas a percentage format often impeded understanding. For example, many participants misinterpreted a relative risk reduction as referring to an absolute risk reduction. Participants with higher numeracy generally performed better than those with lower numeracy, but all participants benefitted from a frequency format. Limitations are that we used a hypothetical medical scenario and a nonrepresentative sample.
Presenting baseline risk in a frequency format improves understanding of relative risk information, whereas a percentage format is likely to lead to misunderstandings. People's numeracy skills play an important role in correctly understanding medical information. Overall, communicating treatment benefits and harms in the form of relative risk changes remains problematic, even when the baseline risk is explicitly provided.
治疗的益处和危害通常以相对风险降低和增加的形式传达，而医生和患者常常对此产生误解。提高对这类风险信息理解的一个建议是同时传达基线风险。我们研究了：1）基线风险的呈现形式是否会影响对相对风险变化的理解；2）人们的数字能力的中介作用。
我们向非专业人士（N = 1234）呈现了一个关于某种治疗会降低（实验1a、2a）或增加（实验1b、2b）心脏病风险的假设情景。基线风险以百分比或频率的形式给出。在一个强制选择范式中，参与者的任务是根据相对风险降低（或增加）和基线风险来判断治疗组的风险。使用Lipkus 11项量表评估数字能力。
以频率形式传达基线风险有助于正确理解治疗的益处和危害，而百分比形式常常会妨碍理解。例如，许多参与者将相对风险降低误解为绝对风险降低。数字能力较高的参与者总体表现优于数字能力较低的参与者，但所有参与者都从频率形式中受益。局限性在于我们使用了一个假设的医疗情景和一个非代表性样本。
以频率形式呈现基线风险可提高对相对风险信息的理解，而百分比形式可能会导致误解。人们的数字能力在正确理解医学信息方面起着重要作用。总体而言，即使明确提供了基线风险，以相对风险变化的形式传达治疗的益处和危害仍然存在问题。
