Abstract
BackgroundVarious types of framing can influence risk perceptions, which may have an impact on treatment decisions and adherence. One way of framing is the use of verbal terms in communicating the probabilities of treatment effects. We systematically reviewed the comparative effects of words versus numbers in communicating the probability of adverse effects to consumers in written health information.MethodsNine electronic databases were searched up to November 2012. Teams of two reviewers independently assessed studies. Inclusion criteria: randomised controlled trials; verbal versus numerical presentation; context: written consumer health information.ResultsTen trials were included. Participants perceived probabilities presented in verbal terms as higher than in numeric terms: commonly used verbal descriptors systematically led to an overestimation of the absolute risk of adverse effects (Range of means: 3% - 54%). Numbers also led to an overestimation of probabilities, but the overestimation was smaller (2% – 20%). The difference in means ranged from 3.8% to 45.9%, with all but one comparison showing significant results. Use of numbers increased satisfaction with the information (MD: 0.48 [CI: 0.32 to 0.63], p < 0.00001, I2 = 0%) and likelihood of medication use (MD for very common side effects: 1.45 [CI: 0.78 to 2.11], p = 0.0001, I2 = 68%; MD for common side effects: 0.90 [CI: 0.61 to 1.19], p < 0.00001, I2 = 1%; MD for rare side effects: 0.39 [0.02 to 0.76], p = 0.04, I2 = not applicable). Outcomes were measured on a 6-point Likert scale, suggesting small to moderate effects.ConclusionsVerbal descriptors including “common”, “uncommon” and “rare” lead to an overestimation of the probability of adverse effects compared to numerical information, if used as previously suggested by the European Commission. Numbers result in more accurate estimates and increase satisfaction and likelihood of medication use. Our review suggests that providers of consumer health information should quantify treatment effects numerically. Future research should focus on the impact of personal and contextual factors, use representative samples or be conducted in real life settings, measure behavioral outcomes and address whether benefit information can be described verbally.
Highlights
Various types of framing can influence risk perceptions, which may have an impact on treatment decisions and adherence
This systematic review provides evidence that compared to numerical information verbal descriptors commonly used to communicate the frequencies of adverse effects in written health information including “common”, “uncommon” and “rare” lead to an overestimation of the probability of adverse effects, when they are used as previously suggested in the Guidelines of the European Commission
Our review suggests that – whenever possible – adverse treatment effects should be quantified numerically, because they lead to better estimates of risks
Summary
Various types of framing can influence risk perceptions, which may have an impact on treatment decisions and adherence. Patient decisions for and against medical treatments are made in the presence of knowledge of the best available evidence for the benefits and harms of these treatments. Various types of data framing can influence risk perceptions [1]. Framed information on the risk of adverse effects of drugs or other medical interventions may cause misinterpretation of the risks of harms. This may have an impact on treatment decisions and might affect medication adherence. The 1995 contraceptive pill scare in the UK highlights the importance of helping doctors and patients understand risk information: media reports and “Dear Doctor” letters reported that the third-generation contraceptive pills increased the (relative) risk of blood clots by 100%, which caused many women to stop taking the pill and led to many unwanted pregnancies and abortions – the absolute risk increase was as small as 0.014% [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
