How numeracy influences risk comprehension and medical decision making

Glucose meters with built-in automated bolus calculator: gadget or real value for insulin-treated diabetic patients?

Self-monitoring of blood glucose is now widely recognized as efficacious to enhance and facilitate diabetes management. More than just a means of recording and storing data, some blood glucose meters (BGMs) are now designed with an embedded automated bolus calculator (ABC) with the goal to propose patients recommendations about insulin dosage. The growing literature in this field tends to claim that these new smart BGMs make patient's life easier and decision making safer. The main purpose of this review is to verify whether BGMs with a built-in ABC indeed improve the willingness and the ability of insulin-treated patients to make adequate therapeutic decisions and positively impact the metabolic control and the quality of life of ABC users. It appears that, as long as the education provided by caregivers remains a top priority, BGMs with a built-in ABC (more than just electronic gadgets) can be regarded as bringing real value to insulin-treated patients with diabetes.

Communicating quantitative information about unexploded ordnance risks to the public

Military base closures have left 600,000 acres of U.S. land contaminated with unexploded ordnance (UXO). Recent research has demonstrated a method for quantifying the probability of residual UXO harming future land users. Here, we explore how a community neighboring a closed, UXO-contaminated military base responds to the probabilistic risk information this method produces. We explore how probabilistic information affects their risk understanding, risk management preferences, risk perceptions, and worry. We test eight different communication formats employing varying combinations of textual risk descriptions, comparative risk information, stacked bar graphs illustrating the proportion of future land users at risk, and textual summaries and/or graphical histograms presenting uncertainty. We find that stacked bar graphs double the odds of correctly reporting the probability of harm and decrease the perceived risk, compared to textual descriptions. Providing histograms or summary uncertainty information decreases the odds of correctly reporting the probability of harm by about one-half, compared to communications without uncertainty information. We also find that risk communication formats do not alter risk management preferences. We recommend that as EPA reevaluates its UXO risk management policies in the coming year, the agency shift to quantitative rather than its current qualitative approach to assessing and communicating UXO risks.

Inferring uncertainty from interval estimates: Effects of alpha level and numeracy

Interval estimates are commonly used to descriptively communicate the degree of uncertainty in numerical values. Conventionally, low alpha levels (e.g., .05) ensure a high probability of capturing the target value between interval endpoints. Here, we test whether alpha levels and individual differences in numeracy influence distributional inferences. In the reported experiment, participants received prediction intervals for fictitious towns’ annual rainfall totals (assuming approximately normal distributions). Then, participants estimated probabilities that future totals would be captured within varying margins about the mean, indicating the approximate shapes of their inferred probability distributions. Results showed that low alpha levels (vs. moderate levels; e.g., .25) more frequently led to inferences of over-dispersed approximately normal distributions or approximately uniform distributions, reducing estimate accuracy. Highly numerate participants made more accurate estimates overall, but were more prone to inferring approximately uniform distributions. These findings have important implications for presenting interval estimates to various audiences.

Managing the primary cesarean delivery rate

One third of deliveries in the United States are by cesarean, a rate that far exceeds that recommended by professional organizations and experts. A dominant reason for the high overall cesarean rate is the rising primary cesarean rate. The high primary cesarean rate results from multiple factors, both clinical and nonclinical. This review outlines proposed interventions to lower the primary cesarean rate. We focus on those implementable at a facility level and would likely yield immediate results, including aligning provider incentives for vaginal birth, limiting elective induction of labor, and improving labor management of dystocia and abnormal fetal heart rate tracings.

The effectiveness of a graphical presentation in addition to a frequency format in the context of familial breast cancer risk communication: a multicenter controlled trial

Background

Inadequate understanding of risk among counselees is a common problem in familial cancer clinics. It has been suggested that graphical displays can help counselees understand cancer risks and subsequent decision-making. We evaluated the effects of a graphical presentation in addition to a frequency format on counselees’ understanding, psychological well-being, and preventive intentions.

Design: Multicenter controlled trial.

Setting: Three familial cancer clinics in the Netherlands.

Methods

Participants: Unaffected women with a breast cancer family history (first-time attendees).

Intervention: Immediately after standard genetic counseling, an additional consultation by a trained risk counselor took place where women were presented with their lifetime breast cancer risk in frequency format (X out of 100) (n = 63) or frequency format plus graphical display (10 × 10 human icons) (n = 91).

Main outcome measures: understanding of risk (risk accuracy, risk perception), psychological well-being, and intentions regarding cancer prevention. Measurements were assessed using questionnaires at baseline, 2-week and 6-month follow-up.

Results

Baseline participant characteristics did not differ between the two groups. In both groups there was an increase in women’s risk accuracy from baseline to follow-up. No significant differences were found between women who received the frequency format and those who received an additional graphical display in terms of understanding, psychological well-being and intentions regarding cancer prevention. The groups did not differ in their evaluation of the process of counseling.

Conclusion

Women’s personal risk estimation accuracy was generally high at baseline and the results suggest that an additional graphical display does not lead to a significant benefit in terms of increasing understanding of risk, psychological well-being and preventive intentions.

Trial registration

Current Controlled Trials http://ISRCTN14566836

Fuzzy trace theory and medical decisions by minors: differences in reasoning between adolescents and adults

Standard models of adolescent risk taking posit that the cognitive abilities of adolescents and adults are equivalent, and that increases in risk taking that occur during adolescence are the result of socio emotional differences in impulsivity, sensation seeking, and lack of self-control. Fuzzy-trace theory incorporates these socio emotional differences. However, it predicts that there are also cognitive differences between adolescents and adults, specifically that there are developmental increases in gist-based intuition that reflects understanding. Gist understanding, as opposed to verbatim-based analysis, generally has been hypothesized to have a protective effect on risk taking in adolescence. Gist understanding is also an essential element of informed consent regarding risks in medical decision- making. Evidence thus supports the argument that adolescents' status as mature minors should be treated as an exception rather than a presumption, because accuracy in verbatim analysis is not mature gist understanding. Use of the exception should be accompanied by medical experts' input on the bottom-line gist of risks involved in treatment.

Development and Testing of an Abbreviated Numeracy Scale: A Rasch Analysis Approach

Research has demonstrated that individual differences in numeracy may have important consequences for decision making. In the present paper, we develop a shorter, psychometrically improved measure of numeracy-the ability to understand, manipulate, and use numerical information, including probabilities. Across two large independent samples that varied widely in age and educational level, participants completed 18 items from existing numeracy measures. In Study 1, we conducted a Rasch analysis on the item pool and created an eight-item numeracy scale that assesses a broader range of difficulty than previous scales. In Study 2, we replicated this eight-item scale in a separate Rasch analysis using data from an independent sample. We also found that the new Rasch-based numeracy scale, compared with previous measures, could predict decision-making preferences obtained in past studies, supporting its predictive validity. In Study, 3, we further established the predictive validity of the Rasch-based numeracy scale. Specifically, we examined the associations between numeracy and risk judgments, compared with previous scales. Overall, we found that the Rasch-based scale was a better linear predictor of risk judgments than prior measures. Moreover, this study is the first to present the psychometric properties of several popular numeracy measures across a diverse sample of ages and educational level. We discuss the usefulness and the advantages of the new scale, which we feel can be used in a wide range of subject populations, allowing for a more clear understanding of how numeracy is associated with decision processes. Copyright © 2012 John Wiley & Sons, Ltd.

On avoiding framing effects in experienced decision makers

The present study aimed to (a) demonstrate the effect of positive–negative framing on experienced criminal justice decision makers, (b) examine the debiasing effect of visually structured risk messages, and (c) investigate whether risk perceptions mediate the debiasing effect of visual aids on decision making. In two phases, 60 senior police officers estimated the accuracy of a counterterrorism technique in identifying whether a known terror suspect poses an imminent danger and decided whether they would recommend the technique to policy makers. Officers also rated their confidence in this recommendation. When information about the effectiveness of the counterterrorism technique was presented in a numerical format, officers' perceptions of accuracy and recommendation decisions were susceptible to the framing effect: The technique was perceived to be more accurate and was more likely to be recommended when its effectiveness was presented in a positive than in a negative frame. However, when the information was represented visually using icon arrays, there were no such framing effects. Finally, perceptions of accuracy mediated the debiasing effect of visual aids on recommendation decisions. We offer potential explanations for the debiasing effect of visual aids and implications for communicating risk to experienced, professional decision makers.

Risky choice in younger versus older adults: Affective context matters

Earlier frameworks have indicated that older adults tend to experience decline in their deliberative decisional capacity, while their affective abilities tend to remain intact (Peters, Hess, Västfjäll, & Auman, 2007). The present study applied this framework to the study of risky decision-making across the lifespan. Two versions of the Columbia Card Task (CCT) were used to trigger either affective decision-making (i.e., the “warm” CCT) or deliberative decision-making (i.e., the “cold” CCT) in a sample of 158 individuals across the lifespan. Overall there were no age differences in risk seeking. However, there was a significant interaction between age and condition, such that older adults were relatively more risk seeking in the cold condition only. In terms of everyday decision-making, context matters and risk propensity may shift within older adults depending upon the context.

Sample representativeness affects whether judgments are influenced by base rate or sample size

We investigated how people use base rates and sample size information when combining data to make overall probability judgments. Participants considered two samples from an animal population in order to estimate the probability of that animal being aggressive. Participants' judgments were influenced by subpopulation base rates when they were provided and linked to specific samples. When samples were not identified as coming from different subpopulations, judgments typically reflected sample size information. We conclude that 1) People can use base rates when combining samples to make an inference; 2) People can correctly use sampling information to determine when to use base rates, and 3) People are able to consider base rate and sample size information at the same time. Additionally, we found that individuals' numeracy correlates with the extent to which base rate and sample size information is used.

Subjective numeracy scale as a tool for assessing statistical numeracy in older adult populations

BACKGROUND

Statistical numeracy, necessary for making informed medical decisions, is reduced among older adults who make more decisions about their medical care and treatment than at any other stage of life. Objective numeracy scales are a source of anxiety among patients, heightened among older adults.

OBJECTIVE

We investigate the subjective numeracy scale as an alternative tool for measuring statistical numeracy with older adult samples.

METHODS

Numeracy was assessed using objective measures for 526 adults ranging in age from 18 to 93 years, and all participants provided subjective numeracy ratings.

RESULTS

Subjective numeracy correlated highly with objective measurements among oldest adults (70+ years; r = 0.51, 95% CI 0.32, 0.66), and for younger age groups. Subjective numeracy explained 33.2% of age differences in objective numeracy.

CONCLUSION

The subjective numeracy scale provides an effective tool for assessing statistical numeracy for broad age ranges and circumvents problems associated with objective numeracy measures.

An application of a diabetes knowledge scale for low-literate Hispanic/Latinos

PURPOSE

The threefold purpose of this study is to assess diabetes knowledge among Hispanic/Latinos attending a culturally sensitive, empowerment-based, diabetes self-management education program; second, to examine the utility of the Spoken Knowledge in Low Literacy in Diabetes (SKILLD) scale as an assessment tool for this population; and third, to assess the relationship between hemoglobin A1C and knowledge improvement in the intervention group.

METHOD

A prospective, quasi-experimental, repeated-measure design tested pre- and post-A1C and diabetes knowledge using the SKILLD scale. The sample consisted of 71 in the intervention group and 64 controls.

RESULTS

Most participants were female, marginally acculturated, and, on average, 60 years of age. Both groups were similar in baseline diabetes knowledge score (median 6 out of 10), and higher literacy was significantly related to increased baseline knowledge. The intervention group significantly improved at follow-up compared with the controls: Participants in the intervention with low baseline knowledge scores had a mean follow-up score of 5.6; those with a high baseline score had a mean score of 7.6. The intervention cohort scored significantly better in knowing why to see an eye doctor, what are normal fasting blood glucose and A1C, and understanding long-term diabetes complications. Increased knowledge of a normal fasting blood glucose level had a significant effect on follow-up A1C in the intervention group.

CONCLUSION

The intervention favorably affects diabetes knowledge, and the SKILLD scale has utility with low-literate Hispanic/Latinos. The significant impact on A1C by diabetes knowledge gain shows that the empowerment-based diabetes self-management education was successful for this ethnic population.

Links Between the Intuitive Sense of Number and Formal Mathematics Ability

Humans share with other animals a system for thinking about numbers in an imprecise and intuitive way. The Approximate Number System (ANS) that underlies this thinking is present throughout the lifespan, is entirely nonverbal, and supports basic numerical computations like comparing, adding, and subtracting quantities. Humans, unlike other animals, also have a system for representing exact numbers. This linguistically mediated system is slowly mastered over the course of many years and provides the basis for most of our formal mathematical thought. A growing body of evidence suggests that the nonverbal ANS and the culturally invented system of exact numbers are fundamentally linked. In this article, we review evidence for this relationship, describing how group and individual differences in the ANS correlate with and even predict formal math ability. In this way, we illustrate how a system of ancient core knowledge may serve as a foundation for more complex mathematical thought.

More Is Not Always Better: Intuitions About Effective Public Policy Can Lead to Unintended Consequences

Public policy decisions often appear based on an assumption that providing more options, more information, and greater decision-making autonomy to consumers will produce better outcomes. We examine reasons why this "more-is-better" approach exists based on the psychological literature. Although better outcomes can result from informed consumer choice, we argue that more options, information, and autonomy can also lead to unintended negative consequences. We use mostly health-related policies and guidelines from the United States and elsewhere as exemplars. We consider various psychological mechanisms that cause these unintended consequences including cognitive overload, affect, and anticipated regret, information salience and availability, and trust in governments as authoritative information providers. We also point toward potential solutions based on psychological research that may reduce the negative unintended consequences of a "more-is-better" approach.

Health numeracy and cognitive decline in advanced age

The study aimed at investigating health numeracy in cognitively well performing healthy participants aged from 50 to 95 years as well as in participants with cognitive impairment, but no dementia (CIND). In cognitively well performing participants (n = 401), demographic variables and cognitive abilities (executive functions, reading comprehension, mental calculation, vocabulary) were associated with health numeracy. Older age, lower education, female gender as well as lower cognitive functions predicted low health numeracy. The effect of older age was partly mediated by executive functions and calculation abilities. Participants with CIND (n = 51) performed significantly lower than healthy controls in health numeracy. The findings suggest that cognitively well performing old individuals have difficulties in understanding health-related numerical information. The risk of misunderstanding health-related numerical information is increased in persons with CIND. As these population groups are frequently involved in health care decisions, particular attention has to be paid to providing numerical information in comprehensible form.

Communication about colorectal cancer screening in Britain: public preferences for an expert recommendation

BACKGROUND

Informed decision-making approaches to cancer screening emphasise the importance of decisions being determined by individuals' own values and preferences. However, advice from a trusted source may also contribute to autonomous decision-making. This study examined preferences regarding a recommendation from the NHS and information provision in the context of colorectal cancer (CRC) screening.

METHODS

In face-to-face interviews, a population-based sample of adults across Britain (n=1964; age 50-80 years) indicated their preference between: (1) a strong recommendation to participate in CRC screening, (2) a recommendation alongside advice to make an individual decision, and (3) no recommendation but advice to make an individual decision. Other measures included trust in the NHS and preferences for information on benefits and risks.

RESULTS

Most respondents (84%) preferred a recommendation (47% strong recommendation, 37% recommendation plus individual decision-making advice), but the majority also wanted full information on risks (77%) and benefits (78%). Men were more in favour of a recommendation than women (86% vs 81%). Trust in the NHS was high overall, but the minority who expressed low trust were less likely to want a recommendation.

CONCLUSION

Most British adults want full information on risks and benefits of screening but they also want a recommendation from an authoritative source. An 'expert' view may be an important part of autonomous health decision-making.

Deliberative disjunction: expert and public understanding of outcome uncertainty

Many environmental and risk management decisions are made jointly by technical experts and members of the public. Frequently, their task is to select from among management alternatives whose outcomes are subject to varying degrees of uncertainty. Although it is recognized that how this uncertainty is interpreted can significantly affect decision-making processes and choices, little research has examined similarities and differences between expert and public understandings of uncertainty. We present results from a web-based survey that directly compares expert and lay interpretations and understandings of different expressions of uncertainty in the context of evaluating the consequences of proposed environmental management actions. Participants responded to two hypothetical but realistic scenarios involving trade-offs between environmental and other objectives and were asked a series of questions about their comprehension of the uncertainty information, their preferred choice among the alternatives, and the associated difficulty and amount of effort. Results demonstrate that experts and laypersons tend to use presentations of numerical ranges and evaluative labels differently; interestingly, the observed differences between the two groups were not explained by differences in numeracy or concerns for the predicted environmental losses. These findings question many of the usual presumptions about how uncertainty should be presented as part of deliberative risk- and environmental-management processes.

A focus group study on breast cancer risk presentation: one format does not fit all

Identifying a strategy that would optimize both the communication and understanding of the individual breast cancer risk remains a considerable challenge. This study explored the preferences of women with a family history of breast cancer about six presentation formats of individual breast cancer risk, as calculated from a risk prediction model. Thirty-four unaffected women attending genetic counseling because of a family history of breast cancer participated in six focus groups conducted in Québec City (2), Montréal (2) and Toronto (2), Canada. Six risk formats were presented for a fictitious case involving a 35-year-old woman (1-numerical: cumulative risk probabilities by age until 80 years; 2-risk curves: probabilities expressed in a risk curve that also provided a risk curve for a woman with no family history in first-degree relatives; 3-relative risk of breast cancer by age 80 years; 4 and 5-absolute risk of breast cancer and absolute chance of not developing breast cancer in the next 20 years; 6-qualitative: color-coded figure). Participants were asked to indicate their appreciation of each format. A group discussion followed during which participants commented on each format. The most and least appreciated formats were risk curves and relative risk, respectively. Overall, participants advocated the use of formats that combine quantitative, qualitative and visual features. Using a combination of approaches to communicate individual breast cancer risks could be associated with higher satisfaction of counselees. Given the increasing use of risk prediction models, it may be relevant to consider the preferences of both the counselee and the professional.

Evaluating a combined (frequency and percentage) risk expression to communicate information on medicine side effects to patients

OBJECTIVES

The study evaluated the interpretation of, and preferences for, numerical information on side-effect incidence when presented in three different formats.

METHODS

It used a controlled design, with participants allocated at random to receive one of the three formats. Participants were recruited via a pop-up window on the CancerHelp UK website. The sample comprised 129 website users, of whom 96% were women and 86% had cancer, who received frequency information on four side effects of tamoxifen, using one of three risk expressions (percentages, e.g. 'affects 25% of people'; frequencies, e.g. 'affects 1 in 4 people'; combined, e.g. 'affects 1 in 4 people (25%)'). They then interpreted information on tamoxifen and its effect on health, and estimates of side-effect frequency, and then stated a preference from the three risk expression formats.

KEY FINDINGS

The results showed that the three formats did not influence participants' ratings of the information or their side-effect estimates. However, more than half (53%) the participants preferred the combined (frequency and percentage) format. In conclusion, a combined risk expression format performed no worse than percentages or frequencies alone and was preferred by a majority.

CONCLUSIONS

The three risk expression formats did not differ in their effect on participants' interpretations. However, the preferred format was the combined (frequency and percentage) risk expression.

Conceptual, methodological, and ethical problems in communicating uncertainty in clinical evidence

The communication of uncertainty in clinical evidence is an important endeavor that poses difficult conceptual, methodological, and ethical problems. Conceptual problems include logical paradoxes in the meaning of probability and "ambiguity"--second-order uncertainty arising from the lack of reliability, credibility, or adequacy of probability information. Methodological problems include questions about optimal methods for representing fundamental uncertainties and for communicating these uncertainties in clinical practice. Ethical problems include questions about whether communicating uncertainty enhances or diminishes patient autonomy and produces net benefits or harms. This article reviews the limited but growing literature on these problems and efforts to address them and identifies key areas of focus for future research. It is argued that the critical need moving forward is for greater conceptual clarity and consistent representational methods that make the meaning of various uncertainties understandable, and for clinical interventions to support patients in coping with uncertainty in decision making.

To what extent do politeness expectations shape risk perception? Even numerical probabilities are under their spell!

Politeness theory posits that uncertainty quantifiers can be interpreted as hedging strategies and thus be perceived as communicating greater certainty than when they are interpreted as likelihood-communication devices. This has only been tested with verbal probabilities (e.g., it is possible). The present paper aims to test whether numerical probabilities can also be interpreted as face-management devices and to investigate the effect of such an interpretation on risk perception. Four experiments focused on the effect of interpretations of numerical probabilities in negative outcome predictions on risk perception (e.g., there is a 50% probability that your stocks will lose their value). Politeness expectation was manipulated by the personality of the speaker (i.e., blunt vs. tactful, Experiments 1 and 2) and according to the conversational partners' need for politeness (Experiments 3 and 4). Results show that numerical probabilities, like verbal ones, were interpreted as likelihood-communication or face-management devices and that the two interpretations led to different risk perceptions. Findings were replicated with different formats, such as percentage (e.g., 50%) and chance ratio (e.g., 1 chance in 3) and with different degrees of certainty (e.g., .30, .50 and .70). Theoretical and practical implications relevant to risk communication are presented and discussed.

A theoretical framework for measuring knowledge in screening decision aid trials

OBJECTIVE

To describe a theoretical framework for assessing knowledge about the possible outcomes of participating in bowel cancer screening for the faecal occult blood test.

METHODS

The content of the knowledge measure was based on the UK General Medical Council's screening guidelines and a theory-based approach to assessing gist knowledge (Fuzzy Trace Theory). It comprised conceptual and numeric questions to assess knowledge of the underlying construct (e.g. false positive concept) and the approximate numbers affected (e.g. likelihood of a false positive). The measure was used in a randomised controlled trial involving 530 adults with low education, to compare the impact of a bowel screening decision aid with a screening information booklet developed for the Australian Government National Bowel Cancer Screening Program.

RESULTS

The numeric knowledge scale was particularly responsive to the effects of the decision aid; at follow-up decision aid participants' numeric knowledge was significantly greater than the controls (P<0.001). This contrasts with the conceptual knowledge scale which improved significantly in both groups from baseline to follow-up (P<0.001).

CONCLUSION

Our theory-based knowledge measure was responsive to change in conceptual knowledge and to the effect on numeric knowledge of a decision aid.

PRACTICE IMPLICATIONS

This theoretical framework has the potential to guide the development of knowledge measures in other screening settings.

The representation of risk in routine medical experience: what actions for contemporary health policy?

Background

The comprehension of appropriate information about illnesses and treatments, can have beneficial effects on patients’ satisfaction and on important health outcomes. However, it is questionable whether people are able to understand risk properly.

Aim

To describe patients’ representation of risk in common medical experiences by linking such a representation to the concept of trust. A further goal was to test whether the representation of risk in the medical domain is associated to the level of expertise. The third goal was to verify whether socio-demographic differences influence the representation of risk.

Methods

Eighty voluntary participants from 6 health-centers in northern Italy were enrolled to conduct a semi-structured interview which included demographic questions, term-associations about risk representation, closed and open questions about attitudes and perception of risk in the medical context, as well as about medical expertise and trust.

Results

The results showed that people do not have in mind a scientific definition of risk in medicine. Risk is seen as a synonym for surgery and disease and it is often confused with fear. However, general knowledge of medical matters helps people to have a better health management through risk identification and risk information, adoption of careful behaviors and tendency to have a critical view about safety and medical news. Finally, trust proved to be an important variable in risk representation and risk and trust were correlated positively.

Conclusions

People must receive appropriate information about the risks and benefits of treatment, in a form that they can understand and apply to their own circumstances. Moreover, contemporary health policy should empower patients to adopt an active self-care attitude. Methodologies to enhance people’s decision-making outcomes based on better risk communication should be improved in order to enable low literacy population as well elderly people to better understand their treatment and associated risk.

Using Comparison Scenarios to Improve Prenatal Risk Communication

The present research provides empirical evidence of whether communicating the prenatal risk of chromosomal anomalies using comparison scenarios influences women’s ability to distinguish between different risk levels. In 2 experiments, participants read a description of a hypothetical woman who was learning of the risk of chromosomal anomaly as a result of a prenatal screening test. Both experiments used a 3 (risk level) × 3 (scenario) full between-subjects design. In accordance with the experimental condition, participants were presented with a low (e.g., 1 in 5390), a medium (e.g., 1 in 770), or a high risk value (e.g., 1 in 110). Such risk values were presented either on their own or along with additional information illustrating a comparison scenario that provided 2 numerical comparison points. Participants were asked to evaluate the risk of chromosomal anomaly. In Experiment 2, participants’ numeracy skills were also assessed. Results showed that the use of comparison scenarios results in significant differences in perceived risk across risk levels whereas such differences are not significant without the comparison scenario, but such a technique has differential effects according to participants’ capacity to deal with numbers. Although the technique is beneficial for high-numerate participants, it has no effect on low-numerate participants.

Exploring objective and subjective numeracy at a population level: findings from the 2007 Health Information National Trends Survey (HINTS)

Numeracy is a critical component of decision making in health, and low numeracy may adversely affect risk comprehension, medical treatment, and health outcomes. Health researchers have developed objective and subjective measures of numeracy that potentially could be used for clinical or health research purposes. To examine the association between objective and subjective numeracy at a population level, data were obtained from the 2007 Health Information National Trends Survey, a health communication survey that collects data from a nationally representative sample of the U.S. population. Associations between items from 2 published subjective numeracy measures (STAT-Confidence Scale; Subjective Numeracy Scale) and a single published objective numeracy measure were examined with respect to one another and with respect to sociodemographic characteristics using a multivariate logistic regression model. Controlling for demographic covariates, both subjective numeracy measures were significantly associated with each other (p < .0001) and with objective numeracy (p < .0001). Compared with respondents who regarded themselves as low in subjective numeracy, those who regarded themselves as high in subjective numeracy had significantly higher odds of answering the objective numeracy question correctly (STAT-Confidence Scale OR = 1.42, CI [1.07, 1.90]; Subjective Numeracy Scale OR = 1.71, CI [1.28, 2.28]). However, the subjective measures performed poorly as diagnostic indicators of objective numeracy. Sensitivity and specificity for the STAT-Confidence Scale and the Subjective Numeracy Scale were 67%/49% and 50%/71%, respectively. More work is needed to elucidate the relation between objective and subjective numeracy, at the conceptual and empirical levels, and to develop more robust measures of subjective numeracy that can better discriminate between individuals with low and high objective numeracy.

The communications revolution and health inequalities in the 21st century: implications for cancer control

The radical and transformative developments in information and communication technologies (ICT) offer unprecedented opportunities to promote cancer control and enhance population and individual health. However, the current context in which these technologies are being deployed--where cancer incidence and mortality and communication are characterized by inequalities among different racial/ethnic and socioeconomic status groups--raises important questions for cancer communication research, policy, and practice. Drawing on illustrative data, this essay characterizes the communications revolution and elucidates its implications for cancer control, with a particular focus on communication inequalities and cancer disparities.

Individual Differences in Numeracy and Cognitive Reflection, with Implications for Biases and Fallacies in Probability Judgment

Despite evidence that individual differences in numeracy affect judgment and decision making, the precise mechanisms underlying how such differences produce biases and fallacies remain unclear. Numeracy scales have been developed without sufficient theoretical grounding, and their relation to other cognitive tasks that assess numerical reasoning, such as the Cognitive Reflection Test (CRT), has been debated. In studies conducted in Brazil and in the USA, we administered an objective Numeracy Scale (NS), Subjective Numeracy Scale (SNS), and the CRT to assess whether they measured similar constructs. The Rational-Experiential Inventory, inhibition (go/no-go task), and intelligence were also investigated. By examining factor solutions along with frequent errors for questions that loaded on each factor, we characterized different types of processing captured by different items on these scales. We also tested the predictive power of these factors to account for biases and fallacies in probability judgments. In the first study, 259 Brazilian undergraduates were tested on the conjunction and disjunction fallacies. In the second study, 190 American undergraduates responded to a ratio-bias task. Across the different samples, the results were remarkably similar. The results indicated that the CRT is not just another numeracy scale, that objective and subjective numeracy scales do not measure an identical construct, and that different aspects of numeracy predict different biases and fallacies. Dimensions of numeracy included computational skills such as multiplying, proportional reasoning, mindless or verbatim matching, metacognitive monitoring, and understanding the gist of relative magnitude, consistent with dual-process theories such as fuzzy-trace theory.

Health numeracy in Japan: measures of basic numeracy account for framing bias in a highly numerate population

BACKGROUND

Health numeracy is an important factor in how well people make decisions based on medical risk information. However, in many countries, including Japan, numeracy studies have been limited.

METHODS

To fill this gap, we evaluated health numeracy levels in a sample of Japanese adults by translating two well-known scales that objectively measure basic understanding of math and probability: the 3-item numeracy scale developed by Schwartz and colleagues (the Schwartz scale) and its expanded version, the 11-item numeracy scale developed by Lipkus and colleagues (the Lipkus scale).

RESULTS

Participants' performances (n = 300) on the scales were much higher than in original studies conducted in the United States (80% average item-wise correct response rate for Schwartz-J, and 87% for Lipkus-J). This high performance resulted in a ceiling effect on the distributions of both scores, which made it difficult to apply parametric statistical analysis, and limited the interpretation of statistical results. Nevertheless, the data provided some evidence for the reliability and validity of these scales: The reliability of the Japanese versions (Schwartz-J and Lipkus-J) was comparable to the original in terms of their internal consistency (Cronbach's α = 0.53 for Schwartz-J and 0.72 for Lipkus-J). Convergent validity was suggested by positive correlations with an existing Japanese health literacy measure (the Test for Ability to Interpret Medical Information developed by Takahashi and colleagues) that contains some items relevant to numeracy. Furthermore, as shown in the previous studies, health numeracy was still associated with framing bias with individuals whose Lipkus-J performance was below the median being significantly influenced by how probability was framed when they rated surgical risks. A significant association was also found using Schwartz-J, which consisted of only three items.

CONCLUSIONS

Despite relatively high levels of health numeracy according to these scales, numeracy measures are still important determinants underlying susceptibility to framing bias. This suggests that it is important in Japan to identify individuals with low numeracy skills so that risk information can be presented in a way that enables them to correctly understand it. Further investigation is required on effective numeracy measures for such an intervention in Japan.

Understanding and using comparative healthcare information; the effect of the amount of information and consumer characteristics and skills

Background

Consumers are increasingly exposed to comparative healthcare information (information about the quality of different healthcare providers). Partly because of its complexity, the use of this information has been limited. The objective of this study was to examine how the amount of presented information influences the comprehension and use of comparative healthcare information when important consumer characteristics and skills are taken into account.

Methods

In this randomized controlled experiment, comparative information on total hip or knee surgery was used as a test case. An online survey was distributed among 800 members of the NIVEL Insurants Panel and 76 hip- or knee surgery patients. Participants were assigned to one of four subgroups, who were shown 3, 7, 11 or 15 quality aspects of three hospitals. We conducted Kruskall-Wallis tests, Chi-square tests and hierarchical multiple linear regression analyses to examine relationships between the amount of information and consumer characteristics and skills (literacy, numeracy, active choice behaviour) on one hand, and outcome measures related to effectively using information (comprehension, perceived usefulness of information, hospital choice, ease of making a choice) on the other hand.

Results

414 people (47%) participated. Regression analysis showed that the amount of information slightly influenced the comprehension and the perceived usefulness of comparative healthcare information. It did not affect consumers’ hospital choice and ease of making this choice. Consumer characteristics (especially age) and skills (especially literacy) were the most important factors affecting the comprehension of information and the ease of making a hospital choice. For the perceived usefulness of comparative information, active choice behaviour was the most influencing factor.

Conclusion

The effects of the amount of information were not unambiguous. It remains unclear what the ideal amount of quality information to be presented would be. Reducing the amount of information will probably not automatically result in more effective use of comparative healthcare information by consumers. More important, consumer characteristics and skills appeared to be more influential factors contributing to information comprehension and use. Consequently, we would suggest that more emphasis on improving consumers’ skills is needed to enhance the use of comparative healthcare information.

Communicating and Distorting Risks with Graphs: An Eye-Tracking Study

Graphs can represent complex information in accessible ways. Unfortunately, many graphs are poorly designed and lead to errors in judgment and decision-making. Here, we examine the influence of distorted graphs used by advertisers and major news organizations to communicate risks. Results indicated that the distorted graphs were associated with large judgment errors and that cognitive abilities (e.g., numeracy, graph literacy, cognitive reflection) predicted differences in error rates. Eye-tracking results revealed a strong link between elaborative information search and stimuli-memory, which mediated the ability-judgment relationship. Discussion focuses on cognitive mechanisms (e.g., elaborative encoding), implications for HFES graph design guidelines, and emerging opportunities for personalized decision support.

Determinants of patient choice of healthcare providers: a scoping review

BACKGROUND

In several northwest European countries, a demand-driven healthcare system has been implemented that stresses the importance of patient healthcare provider choice. In this study, we are conducting a scoping review aiming to map out what is known about the determinants of patient choice of a wide range of healthcare providers. As far as we know, not many studies are currently available that attempt to draw a general picture of how patients choose a healthcare provider and of the status of research on this subject. This study is therefore a valuable contribution to the growing amount of literature about patient choice.

METHODS

We carried out a specific type of literature review known as a scoping review. Scoping reviews try to examine the breadth of knowledge that is available about a particular topic and therefore do not make selections or apply quality constraints. Firstly, we defined our research questions and searched the literature in Embase, Medline and PubMed. Secondly, we selected the literature, and finally we analysed and summarized the information.

RESULTS

Our review shows that patients' choices are determined by a complex interplay between patient and provider characteristics. A variety of patient characteristics determines whether patients make choices, are willing and able to choose, and how they choose. Patients take account of a variety of structural, process and outcome characteristics of providers, differing in the relative importance they attach to these characteristics.

CONCLUSIONS

There is no such thing as the typical patient: different patients make different choices in different situations. Comparative information seems to have a relatively limited influence on the choices made by many patients and patients base their decisions on a variety of provider characteristics instead of solely on outcome characteristics. The assumptions made in health policy about patient choice may therefore be an oversimplification of reality. Several knowledge gaps were identified that need follow-up research.

Effect of Narrative Reports about Vaccine Adverse Events and Bias-Awareness Disclaimers on Vaccine Decisions

Background. As the number of individuals who search for health information in interactive online environments is increasing, patient networks deserve more scientific attention. Objective. To quantitatively examine if and how reading statistical and/or narrative information as typically displayed in patient networks (e.g., patientslikeme.com ) affects decisions for pharmaceuticals. Previous work suggests that narrative information (e.g., about vaccine adverse events, VAE) affects risk perceptions and intentions. The authors compare the effect of narrative and statistical information about VAE on vaccination decisions and examine if a disclaimer reduces the narrative bias as well as if low numeracy leads to increased use of the narratives. Method and Design. In an online experiment, 458 participants were randomly assigned to a 3 (relative frequency of vaccine adverse events in 1, 7, or 17 of 20 cases) × 3 (type of information: narratives, summary statistics, or both) × 2 (bias awareness v. control disclaimer) between-subjects design. Measurements. Perceived risk, vaccination intention, and subjective numeracy. Results. A higher relative frequency of cases reporting VAE decreased the intention to get vaccinated. This relation was mediated by increased risk perception. The type of information moderated the contents’ impact: Summary statistics had the smallest impact, whereas narrative information was more influential, and the presence of both types of information had the greatest impact on risk perception. Individuals who received the bias-awareness disclaimer were less influenced by the patient network. Highly numerate individuals were generally more sensitive to the provided information independent of its format. Conclusions. Patient networks can influence vaccination decisions by delivering risk-related information. Disclaimers may help to reduce the influence if desired.

The impact of health and financial literacy on decision making in community-based older adults

BACKGROUND

Health and financial literacy have been linked to the health and well-being of older adults, yet there are few data on how health and financial literacy actually impact decision making regarding healthcare and economic choices in advanced age.

OBJECTIVE

To examine the association of health and financial literacy with decision making in older adults.

METHOD

Data came from 525 community-dwelling older persons without dementia from the Rush Memory and Aging Project, an ongoing longitudinal study of aging. Health and financial literacy were assessed via a series of questions designed to measure comprehension of health and financial information and concepts. The two scores were averaged to yield a total literacy score. A modified, 12-item version of the Decision-Making Competence Assessment Tool was used to measure financial and healthcare decision making (6 items each), using materials designed to approximate those used in real world settings. All 12 items were summed to yield a total decision-making score. Associations were tested via linear regression models adjusted for age, sex and education. Secondary models adjusted for global cognitive function, income, depression and chronic medical conditions.

RESULTS

On average, participants correctly answered 67% of the literacy questions (health literacy = 61.6%, SD = 18.8% and financial literacy = 72.5%, SD = 16.0%). After adjustment for cognitive function, the total literacy score was positively associated with the decision-making total score (estimate = 0.64, SE = 0.08, p < 0.001), as well as healthcare (estimate = 0.37, SE = 0.5, p < 0.001) and financial decision making (estimate = 0.28, SE = 0.05, p < 0.001). Further, total literacy, health and financial literacy all were independently associated with decision making in models adjusted for covariates including income, depression, and chronic medical conditions (all p values < 0.001). Finally, there was evidence of effect modification such that the beneficial association between literacy and healthcare decision making was stronger among older persons, poorer persons and persons at the lower ranges of cognitive ability.

CONCLUSION

Among community based older persons without dementia, higher levels of health and financial literacy were associated with better decision making, suggesting that improvements in literacy could facilitate better decision making and lead to better health and quality of life in later years.

A Kenyan newspaper analysis of the limitations of voluntary medical male circumcision and the importance of sustained condom use

BACKGROUND

Since the completion of three clinical trials indicating that voluntary medical male circumcision (VMMC) is an effective method to reduce men's chances of acquiring HIV, use of the procedure has been advocated in Kenya. Media messages shape popular understandings of the benefits and limitations of male circumcision. The objectives of this study were to (1) investigate promotion messages in a popular online newspaper to determine how the limitations of male circumcision are represented, and whether condom use is still being promoted; and (2) gain insight into popular understandings of the limitations of this new procedure through newspaper reader comments.

METHODS

A content analysis was conducted on 34 online media articles published by the Daily Nation between January 1, 2008 and December 31, 2010. Information about condom promotion, partial immunity, limitations and complications of the procedure, as well as emergent themes, were analyzed.

RESULTS

Results demonstrated an irregular and occasionally misleading presentation of these topics and a perceived lack of objective information about the risks and limitations of VMMC.

CONCLUSIONS

There is a need for governmental and non-governmental public health organizations to engage with the media to improve risk messaging.

Improving communication of breast cancer recurrence risk

Doctors commonly use genomic testing for breast cancer recurrence risk. We sought to assess whether the standard genomic report provided to doctors is a good approach for communicating results to patients. During 2009-2010, we interviewed 133 patients with stages I or II, node-negative, hormone receptor-positive breast cancer and eligible for the Oncotype DX genomic test. In a randomized experiment, patients viewed six vignettes that presented hypothetical recurrence risk test results. Each vignette described a low, intermediate, or high chance of breast cancer recurrence in 10 years. Vignettes used one of five risk formats of increasing complexity that we derived from the standard report that accompanies the commercial assay or a sixth format that used an icon array. Among women who received the genomic recurrence risk test, 63% said their doctors showed them the standard report. The standard report format yielded among the most errors in identification of whether a result was low, intermediate, or high risk (i.e., the gist of the results), whereas a newly developed risk continuum format yielded the fewest errors (17% vs. 5%; OR 0.23; 95% CI 0.10-0.52). For high recurrence risk results presented in the standard format, women made errors 35% of the time. Women rated the standard report as one of the least understandable and least-liked formats, but they rated the risk continuum format as among the most understandable and most liked. Results differed little by health literacy, numeracy, prior receipt of genomic test results during clinical care, and actual genomic test results. The standard genomic recurrence risk report was more difficult for women to understand and interpret than the other formats. A less complex report, potentially including the risk continuum format, would be more effective in communicating test results to patients.

Risk perception and communication in vaccination decisions: a fuzzy-trace theory approach

The tenets of fuzzy-trace theory, along with prior research on risk perception and risk communication, are used to develop a process model of vaccination decisions in the era of Web 2.0. The theory characterizes these decisions in terms of background knowledge, dual mental representations (verbatim and gist), retrieval of values, and application of values to representations in context. Lack of knowledge interferes with the ability to extract the essential meaning, or gist, of vaccination messages. Prevention decisions have, by definition, a status quo option of "feeling okay." Psychological evidence from other prevention decisions, such as cancer screening, indicates that many people initially mentally represent their decision options in terms of simple, categorical gist: a choice between (a) a feeling-okay option (e.g., the unvaccinated status quo) versus (b) taking up preventive behavior that can have two potential categorical outcomes: feeling okay or not feeling okay. Hence, applying the same theoretical rules as used to explain framing effects and the Allais paradox, the decision to get a flu shot, for example, boils down to feeling okay (not sick) versus feeling okay (not sick) or not feeling okay (sick, side effects, or death). Because feeling okay is superior to not feeling okay (a retrieved value), this impoverished gist supports choosing not to have the flu vaccine. Anti-vaccination sources provide more coherent accounts of the gist of vaccination than official sources, filling a need to understand rare adverse outcomes.

When and for whom do frequencies facilitate performance? On the role of numerical literacy

The thesis that the mind is better prepared to process frequencies-as compared to other numerical formats-continues to be debated. A recent aspect of this issue is the role of numeracy (numerical literacy; one's ability to understand and work with numerical information) and specifically the argument that individual differences in numeracy interact with numerical formats. This interaction, either that frequencies improve performance only for those of low numeracy or that frequencies work only for those of high numeracy, would suggest that better performance using frequencies could be due to (nonevolutionary) numeracy effects. The three present studies revisited prior work with cumulative probability, Bayesian reasoning, and scenario risk assessments to study the effects of numeracy on frequency facilitation. Results from these experiments consistently failed to replicate previous findings of interactions; however, a more consistent finding emerged of a straightforward frequency effect. The lack of interactions and observations of frequency main effects lend support to the evolutionary explanation of the frequency effect. In addition, some possible statistical processes are proposed to explain the observation of interactions in past studies.

How well do commonly used data presentation formats support comparative effectiveness evaluations?

BACKGROUND

Good decisions depend on an accurate understanding of the comparative effectiveness of decision alternatives. The best way to convey data needed to support these comparisons is unknown.

OBJECTIVE

To determine how well 5 commonly used data presentation formats convey comparative effectiveness information.

METHODS

The study was an Internet survey using a factorial design. Participants consisted of 279 members of an online survey panel. Study participants compared outcomes associated with 3 hypothetical screening test options relative to 5 possible outcomes with probabilities ranging from 2 per 5000 (0.04%) to 500 per 1000 (50%). Data presentation formats included a table, a "magnified" bar chart, a risk scale, a frequency diagram, and an icon array. Outcomes included the number of correct ordinal judgments regarding the more likely of 2 outcomes, the ratio of perceived versus actual relative likelihoods of the paired outcomes, the intersubject consistency of responses, and perceived clarity.

RESULTS

The mean number of correct ordinal judgments was 12 of 15 (80%), with no differences among data formats. On average, there was a 3.3-fold difference between perceived and actual likelihood ratios (95% confidence interval = 3.0-3.6). Comparative judgments based on flowcharts, icon arrays, and tables were all significantly more accurate and consistent than those based on risk scales and bar charts (P < 0.001). The most clearly perceived formats were the table and the flowchart. Low subjective numeracy was associated with less accurate and more variable data interpretations and lower perceived clarity for icon displays, bar charts, and flow diagrams.

CONCLUSIONS

None of the data presentation formats studied can reliably provide patients, especially those with low subjective numeracy, with an accurate understanding of comparative effectiveness information.

Do the British public recognise differences in survival between three common cancers?

BACKGROUND

The recognition that cancer is not a single entity, rather that different cancers have different causes and trajectories, has been a key development in the scientific understanding of cancer. However, little is known about the British public's awareness of differences between cancers. This study examined differences in perceived survivability for three common cancers with widely disparate survival rates (breast, colorectal and lung).

METHOD

In a population-based survey, using home interviews (N=2018), respondents answered a quantitative (numeric) question on 5-year survival and a qualitative (non-numeric) question on curability, for each of the three cancers.

RESULTS

British adults correctly recognised that 5-year survival for breast cancer was higher than for colorectal cancer (CRC), which in turn was recognised to be higher than for lung cancer. Similarly, curability was perceived to be higher for breast than CRC, and both were perceived to be more curable than lung cancer. Awareness of survival differences did not vary by sex, age or socioeconomic status. In terms of absolute values, there was a tendency to underestimate breast cancer survival and overestimate lung cancer survival.

CONCLUSION

The British public appear to be aware that not all cancers are equally fatal.

Using visual aids to improve communication of risks about health: a review

Recent research has shown that patients frequently experience difficulties understanding health-relevant numerical concepts. A prominent example is denominator neglect, or the tendency to pay too much attention to numerators in ratios (e.g., number of treated patients who died) with insufficient attention to denominators (e.g., overall number of treated patients). Denominator neglect can lead to inaccurate assessments of treatment risk reduction and thus can have important consequences for decisions about health. Here, we reviewed a series of studies investigating (1) different factors that can influence patients' susceptibility to denominator neglect in medical decision making—including numerical or language-related abilities; (2) the extent to which denominator neglect can be attenuated by using visual aids; and (3) a factor that moderates the effectiveness of such aids (i.e., graph literacy). The review spans probabilistic national U.S. and German samples, as well as immigrant (i.e., Polish people living in the United Kingdom) and undergraduate samples in Spain. Theoretical and prescriptive implications are discussed.

Image Theory’s counting rule in clinical decision making: Does it describe how clinicians make patient-specific forecasts?

The field of clinical decision making is polarized by two predominate views. One holds that treatment recommendations should conform with guidelines; the other emphasizes clinical expertise in reaching case-specific judgments. Previous work developed a test for a proposed alternative, that clinical judgment should systematically incorporate both general knowledge and patient-specific information. The test was derived from image theory’s two phase-account of decision making and its “simple counting rule”, which describes how possible courses of action are pre-screened for compatibility with standards and values. The current paper applies this rule to clinical forecasting, where practitioners indicate how likely a specific patient will respond favorably to a recommended treatment. Psychiatric trainees evaluated eight case vignettes that exhibited from 0 to 3 incompatible attributes. They made two forecasts, one based on a guideline recommendation, the other based on their own alternative. Both forecasts were predicted by equally- and unequally-weighted counting rules. Unequal weighting provided a better fit and exhibited a clearer rejection threshold, or point at which forecasts are not diminished by additional incompatibilities. The hypothesis that missing information is treated as an incompatibility was not confirmed. There was evidence that the rejection threshold was influenced by clinician preference. Results suggests that guidelines may have a de-biasing influence on clinical judgment. Subject to limitations pertaining to the subject sample and population, clinical paradigm, guideline, and study procedure, the data support the use of a compatibility test to describe how clinicians make patient-specific forecasts.

A new intuitionism: Meaning, memory, and development in Fuzzy-Trace Theory

Combining meaning, memory, and development, the perennially popular topic of intuition can be approached in a new way. Fuzzy-trace theory integrates these topics by distinguishing between meaning-based gist representations, which support fuzzy (yet advanced) intuition, and superficial verbatim representations of information, which support precise analysis. Here, I review the counterintuitive findings that led to the development of the theory and its most recent extensions to the neuroscience of risky decision making. These findings include memory interference (worse verbatim memory is associated with better reasoning); nonnumerical framing (framing effects increase when numbers are deleted from decision problems); developmental decreases in gray matter and increases in brain connectivity; developmental reversals in memory, judgment, and decision making (heuristics and biases based on gist increase from childhood to adulthood, challenging conceptions of rationality); and selective attention effects that provide critical tests comparing fuzzy-trace theory, expected utility theory, and its variants (e.g., prospect theory). Surprising implications for judgment and decision making in real life are also discussed, notably, that adaptive decision making relies mainly on gist-based intuition in law, medicine, and public health.