The importance of high-quality evidence of the long-term impact of nonfatal events used in randomized controlled trials: a case study of prasugrel

Current Best Practice for Presenting Probabilities in Patient Decision Aids: Fundamental Principles

BACKGROUND

Shared decision making requires evidence to be conveyed to the patient in a way they can easily understand and compare. Patient decision aids facilitate this process. This article reviews the current evidence for how to present numerical probabilities within patient decision aids.

METHODS

Following the 2013 review method, we assembled a group of 9 international experts on risk communication across Australia, Germany, the Netherlands, the United Kingdom, and the United States. We expanded the topics covered in the first review to reflect emerging areas of research. Groups of 2 to 3 authors reviewed the relevant literature based on their expertise and wrote each section before review by the full authorship team.

RESULTS

Of 10 topics identified, we present 5 fundamental issues in this article. Although some topics resulted in clear guidance (presenting the chance an event will occur, addressing numerical skills), other topics (context/evaluative labels, conveying uncertainty, risk over time) continue to have evolving knowledge bases. We recommend presenting numbers over a set time period with a clear denominator, using consistent formats between outcomes and interventions to enable unbiased comparisons, and interpreting the numbers for the reader to meet the needs of varying numeracy.

DISCUSSION

Understanding how different numerical formats can bias risk perception will help decision aid developers communicate risks in a balanced, comprehensible manner and avoid accidental "nudging" toward a particular option. Decisions between probability formats need to consider the available evidence and user skills. The review may be useful for other areas of science communication in which unbiased presentation of probabilities is important.

Uncertainties in real-world decisions on medical technologies

Patients, clinicians, payers and policy makers face substantial uncertainties in their respective healthcare decisions as they attempt to achieve maximum value, or the greatest level of benefit possible at a given cost. Uncertainties largely come from incomplete information at the time that decisions must be made. This is true in all areas of medicine because evidence from clinical trials is often incongruent with real-world patient care. This article highlights key uncertainties around the (comparative) benefits and harms of medical technologies. Initiatives and strategies such as comparative effectiveness research and coverage with evidence development may help to generate reliable and relevant evidence for decisions on coverage and treatment. These efforts could result in better decisions that improve patient outcomes and better use of scarce medical resources.

Cost–effectiveness of using CYP2C19 genotype to guide selection of clopidogrel or ticagrelor in Australia

Aims: This study aims to assess the cost–effectiveness in Australia of screening CYP2C19 loss-of-function (LoF) alleles to guide selection of clopidogrel or ticagrelor for individuals with acute coronary syndrome who are likely to undergo coronary stenting. Methods: Three treatment strategies were compared: universal clopidogrel therapy, universal ticagrelor therapy and genotyping CYP2C19 with use of ticagrelor for individuals with a LoF allele and clopidogrel for individuals without a LoF allele. Lifetime costs and quality-adjusted life years for each treatment strategy were estimated using a Markov model. The risks of events were primarily derived from the genetic substudy of the pivotal randomized controlled trial. Results: CYP2C19 genotyping resulted in greater effectiveness and was cost-effective when compared with universal use of clopidogrel. However, universal use of ticagrelor was the most effective strategy overall and the incremental cost–effectiveness compared with the genotyping strategy was generally within what is considered acceptable. Conclusion: Ticagrelor is likely to be cost-effective even for individuals not carrying a CYP2C19 LoF allele.

Original submitted 30 May 2013; Revision submitted 16 August 2013

Presenting quantitative information about decision outcomes: a risk communication primer for patient decision aid developers

BACKGROUND

Making evidence-based decisions often requires comparison of two or more options. Research-based evidence may exist which quantifies how likely the outcomes are for each option. Understanding these numeric estimates improves patients' risk perception and leads to better informed decision making. This paper summarises current "best practices" in communication of evidence-based numeric outcomes for developers of patient decision aids (PtDAs) and other health communication tools.

METHOD

An expert consensus group of fourteen researchers from North America, Europe, and Australasia identified eleven main issues in risk communication. Two experts for each issue wrote a "state of the art" summary of best evidence, drawing on the PtDA, health, psychological, and broader scientific literature. In addition, commonly used terms were defined and a set of guiding principles and key messages derived from the results.

RESULTS

The eleven key components of risk communication were: 1) Presenting the chance an event will occur; 2) Presenting changes in numeric outcomes; 3) Outcome estimates for test and screening decisions; 4) Numeric estimates in context and with evaluative labels; 5) Conveying uncertainty; 6) Visual formats; 7) Tailoring estimates; 8) Formats for understanding outcomes over time; 9) Narrative methods for conveying the chance of an event; 10) Important skills for understanding numerical estimates; and 11) Interactive web-based formats. Guiding principles from the evidence summaries advise that risk communication formats should reflect the task required of the user, should always define a relevant reference class (i.e., denominator) over time, should aim to use a consistent format throughout documents, should avoid "1 in x" formats and variable denominators, consider the magnitude of numbers used and the possibility of format bias, and should take into account the numeracy and graph literacy of the audience.

CONCLUSION

A substantial and rapidly expanding evidence base exists for risk communication. Developers of tools to facilitate evidence-based decision making should apply these principles to improve the quality of risk communication in practice.

Challenges and limitations in the interpretation of systematic reviews: making sense of clopidogrel and CYP2C19 pharmacogenetics

From 2010 to 2012, nine systematic reviews reported highly variable conclusions regarding the association between carriage of a cytochrome P450 2C19 loss-of-function allele and the risk of adverse cardiovascular (CV) events in individuals using clopidogrel. Possible contributors to the variable findings include differences in patient populations, CV end points, and statistical models utilized by the systematic reviews, as well as unexplained heterogeneity, inconsistent/incomplete reporting, and risk of publication bias with respect to the primary studies.