How numeracy influences risk comprehension and medical decision making

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.

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.

Descriptive and numeric estimation of risk for psychotic disorders among affected individuals and relatives: implications for clinical practice

Studies show that individuals with psychotic illnesses and their families want information about psychosis risks for other relatives. However, deriving accurate numeric probabilities for psychosis risk is challenging, and people have difficulty interpreting probabilistic information; thus, some have suggested that clinicians should use risk descriptors, such as "moderate" or "quite high", rather than numbers. Little is known about how individuals with psychosis and their family members use quantitative and qualitative descriptors of risk in the specific context of chance for an individual to develop psychosis. We explored numeric and descriptive estimations of psychosis risk among individuals with psychotic disorders and unaffected first-degree relatives. In an online survey, respondents numerically and descriptively estimated risk for an individual to develop psychosis in scenarios where they had: A) no affected family members; and B) an affected sibling. Participants comprised 219 affected individuals and 211 first-degree relatives participated. Affected individuals estimated significantly higher risks than relatives. Participants attributed all descriptors between "very low" and "very high" to probabilities of 1%, 10%, 25% and 50%+. For a given numeric probability, different risk descriptors were attributed in different scenarios. Clinically, brief interventions around risk (using either probabilities or descriptors alone) are vulnerable to miscommunication and potentially negative consequences-interventions around risk are best suited to in-depth discussion.

Commentary on "Performance of a glucose meter with a built-in automated bolus calculator versus manual bolus calculation in insulin-using subjects"

Since the early 2000s, there has been an exponentially increasing development of new diabetes-applied technology, such as continuous glucose monitoring, bolus calculators, and "smart" pumps, with the expectation of partially overcoming clinical inertia and low patient compliance. However, its long-term efficacy in glucose control has not been unequivocally proven. In this issue of Journal of Diabetes Science and Technology, Sussman and colleagues evaluated a tool for the calculation of the prandial insulin dose. A total of 205 insulin-treated patients were asked to compute a bolus dose in two simulated conditions either manually or with the bolus calculator built into the FreeStyle InsuLinx meter, revealing the high frequency of wrong calculations when performed manually. Although the clinical impact of this study is limited, it highlights the potential implications of low diabetesrelated numeracy in poor glycemic control. Educational programs aiming to increase patients' empowerment and caregivers' knowledge are needed in order to get full benefit of the technology.

Beyond Comprehension

When making decisions, people must frequently take into account numerical information, but not all individuals have the ability to understand and use numbers. Less numerate individuals comprehend less numerical information; but numeracy goes beyond comprehension, relating systematically to psychological mechanisms. In particular, greater numeracy has been associated with reduced susceptibility to framing effects, less influence of nonnumerical information such as mood states, and greater sensitivity to different levels of numerical risk. This greater number sensitivity has been linked with number-related affective reactions reported by the highly numerate. I briefly discuss methods to increase number use in decisions and policy implications of numeracy research.

Statistical literacy in obstetricians and gynecologists

The Obstetrician-Gynecologist Statistical Literacy Questionnaire (OGSLQ) was designed to examine physicians' understanding of various number tasks that are relevant to obstetrician-gynecologists (ob-gyns) practice. Forty-seven percent of the nationally representative, practicing ob-gyns responded. Physicians did poorly on the questions about numerical facts (e.g., number of women living with HIV/AIDS), better on questions about statistical concepts (e.g., incidence, prevalence), and best on questions about numerical relationships (e.g., convert frequency to percentage) with 0%, 7%, 36%, answering all correctly, respectively. Only 19% correctly estimated the number of U.S. women with cancer. Sixty-six percent were able to use sensitivity and specificity to choose a test option. Around 90% could translate between frequency and probability formats. Forty-nine percent of respondents were able to calculate the positive predictive value of a mammography screening test. Physicians lack some understanding of statistical literacy. It is important that we monitor physicians' statistical literacy and provide training to students and physicians.

Racial and ethnic differences in direct-to-consumer genetic tests awareness in HINTS 2007: sociodemographic and numeracy correlates

To examine the association of 1) race/ethnicity and 2) numeracy with awareness of DTC genetic tests. Secondary analysis of 6,754 Hispanic, black, and white adult respondents to the National Cancer Institute's 2007 Health Information National Trends Survey (HINTS). Logistic regression was used to examine sociodemographic predictors of DTC genetic tests awareness including race/ethnicity, income, education, and gender. Next, two numeracy variables were added to the model. After controlling for sociodemographic variables, black respondents were significantly less likely to have heard of DTC genetic tests compared to white respondents (OR = 0.79; CI: 0.65-0.97). When numeracy variables were added to the model, the effect of black race was no longer significant (OR = 0.84; CI: 0.69-1.04). Hispanic respondents did not significantly differ from white respondents in awareness of DTC genetic tests. Other significant correlates of DTC genetic tests awareness in the full model included education, income, age, and numeracy variables including degree to which people use medical statistics and numbers to make health decisions, and preference for words or numbers when discussing "the chance of something happening." Although black respondents were generally less aware of DTC genetic tests than white respondents, this relationship appears to be partially mediated by numeracy.

Dynamic links between memory and functional limitations in old age: longitudinal evidence for age-based structural dynamics from the AHEAD study

This study examined competing substantive hypotheses about dynamic (i.e., time-ordered) links between memory and functional limitations in old age. We applied the Bivariate Dual Change Score Model to 13-year longitudinal data from the Asset and Health Dynamics Among the Oldest Old Study (AHEAD; N = 6,990; ages 70 - 95). Results revealed that better memory predicted shallower increases in functional limitations. Little evidence was found for the opposite direction that functional limitations predict ensuing changes in memory. Spline models indicated that dynamic associations between memory and functional limitations were substantively similar between participants aged 70-79 and those aged 80-95. Potential covariates (gender, education, health conditions, and depressive symptoms) did not account for these differential lead-lag associations. Applying a multivariate approach, our results suggest that late-life developments in two key components of successful aging are intrinsically interrelated. Our discussion focuses on possible mechanisms why cognitive functioning may serve as a source of age-related changes in health both among the young-old and the old-old.

Impact of literacy and numeracy on motivation for behavior change after diabetes genetic risk testing

BACKGROUND

Type 2 diabetes genetic risk testing might motivate at-risk patients to adopt diabetes prevention behaviors. However, the influence of literacy and numeracy on patient response to diabetes genetic risk is unknown.

OBJECTIVE

The authors investigated the association of health literacy, genetic literacy, and health numeracy with patient responses to diabetes genetic risk.

DESIGN

and Measurements Overweight patients at high phenotypic risk for type 2 diabetes were recruited for a clinical trial of diabetes genetic risk testing. At baseline, participants predicted how their motivation for lifestyle modification to prevent diabetes might change in response to hypothetical scenarios of receiving "high" and "low" genetic risk results. Responses were analyzed according to participants' health literacy, genetic literacy, and health numeracy.

RESULTS

Two-thirds (67%) of participants (n = 175) reported very high motivation to prevent diabetes. Despite high health literacy (92% at high school level), many participants had limited health numeracy (30%) and genetic literacy (38%). Almost all (98%) reported that high-risk genetic results would increase their motivation for lifestyle modification. In contrast, response to low-risk genetic results varied. Higher levels of health literacy (P = 0.04), genetic literacy (P = 0.02), and health numeracy (P = 0.02) were associated with an anticipated decrease in motivation for lifestyle modification in response to low-risk results.

CONCLUSIONS

While patients reported that high-risk genetic results would motivate them to adopt healthy lifestyle changes, response to low-risk results varied by patient numeracy and literacy. However, anticipated responses may not correlate with true behavior change. If future research justifies the clinical use of genetic testing to motivate behavior change, it may be important to assess how patient characteristics modify that motivational effect.

Measuring Risk Literacy: The Berlin Numeracy Test

We introduce the Berlin Numeracy Test, a new psychometrically sound instrument that quickly assesses statistical numeracy and risk literacy. We present 21 studies (n=5336) showing robust psychometric discriminability across 15 countries (e.g., Germany, Pakistan, Japan, USA) and diverse samples (e.g., medical professionals, general populations, Mechanical Turk web panels). Analyses demonstrate desirable patterns of convergent validity (e.g., numeracy, general cognitive abilities), discriminant validity (e.g., personality, motivation), and criterion validity (e.g., numerical and non-numerical questions about risk). The Berlin Numeracy Test was found to be the strongest predictor of comprehension of everyday risks (e.g., evaluating claims about products and treatments; interpreting forecasts), doubling the predictive power of other numeracy instruments and accounting for unique variance beyond other cognitive tests (e.g., cognitive reflection, working memory, intelligence). The Berlin Numeracy Test typically takes about three minutes to complete and is available in multiple languages and formats, including a computer adaptive test that automatically scores and reports data to researchers (http://www.riskliteracy.org). The online forum also provides interactive content for public outreach and education, and offers a recommendation system for test format selection. Discussion centers on construct validity of numeracy for risk literacy, underlying cognitive mechanisms, and applications in adaptive decision support.

Representing randomness in the communication of individualized cancer risk estimates: effects on cancer risk perceptions, worry, and subjective uncertainty about risk

OBJECTIVE

To test the effect of novel representations of randomness on risk perceptions, worry, and subjective uncertainty about individualized colorectal cancer risk estimates.

METHODS

A web-based factorial experiment was conducted, in which 225 adults aged 40 years and older were provided with hypothetical individualized colorectal cancer risk estimates, using 5 different textual and visual representations varying in expressed randomness. Outcome measures were perceived cancer risk, cancer worry, and subjective uncertainty about cancer risk; the moderating effect of dispositional optimism was also examined.

RESULTS

Representational format was significantly associated with subjective uncertainty about cancer risk, but not with perceived cancer risk or worry. A format using software-based animation to express randomness dynamically led to the highest subjective uncertainty, although a static visual non-random format also increased uncertainty. Dispositional optimism moderated this effect; between-format differences in uncertainty were significant only for participants with low optimism.

CONCLUSION

Representing randomness in individualized estimates of cancer risk increases subjective uncertainty about risk. A novel dynamic visual format produces the greatest effect, which is moderated by individual differences in optimism.

PRACTICE IMPLICATIONS

Novel representations of randomness may be effective in improving people's understanding of the essential uncertainty pertaining to individualized cancer risk estimates.

Brain correlates of mathematical competence in processing mathematical representations

The ability to extract numerical information from different representation formats (e.g., equations, tables, or diagrams) is a key component of mathematical competence but little is known about its neural correlate. Previous studies comparing mathematically less and more competent adults have focused on mental arithmetic and reported differences in left angular gyrus (AG) activity which were interpreted to reflect differential reliance on arithmetic fact retrieval during problem solving. The aim of the present functional magnetic resonance imaging study was to investigate the brain correlates of mathematical competence in a task requiring the processing of typical mathematical representations. Twenty-eight adults of lower and higher mathematical competence worked on a representation matching task in which they had to evaluate whether the numerical information of a symbolic equation matches that of a bar chart. Two task conditions without and one condition with arithmetic demands were administered. Both competence groups performed equally well in the non-arithmetic conditions and only differed in accuracy in the condition requiring calculation. Activation contrasts between the groups revealed consistently stronger left AG activation in the more competent individuals across all three task conditions. The finding of competence-related activation differences independently of arithmetic demands suggests that more and less competent individuals differ in a cognitive process other than arithmetic fact retrieval. Specifically, it is argued that the stronger left AG activity in the more competent adults may reflect their higher proficiency in processing mathematical symbols. Moreover, the study demonstrates competence-related parietal activation differences that were not accompanied by differential experimental performance.

Precision, accuracy, and user acceptance of the OneTouch SelectSimple blood glucose monitoring system

BACKGROUND

The OneTouch® SelectSimple™ blood glucose monitoring system (BGMS) is a device for self-monitoring of blood glucose designed for ease of use. Alarms alert subjects to low [20-69 mg/dl (1.1-3.8 mmol/liter)], high [180-239 mg/dl (9.9-13.2 mmol/liter)], and very high [240-600 mg/dl (13.3-33.1 mmol/liter)] blood glucose readings.

METHODS

Repeatability in blood and intermediate precision with aqueous controls were examined using blood from one donor adjusted to different glucose concentrations, and tested with 10 meters and 1 test-strip lot. System accuracy was evaluated with blood samples from 100 diabetes patients tested on 3 test-strip lots, compared with a reference system (YSI 2300 STAT). To test user accuracy, patients (n = 156) and health care professionals (HCPs) tested subject blood with the SelectSimple twice. Health care professionals evaluated subject BGMS technique after a 3-5 day home-testing period. Users evaluated the instructions for use and responded to a user acceptance questionnaire.

RESULTS

In repeatability and intermediate precision testing, the SelectSimple BGMS had a coefficient of variation of ≤ 5% or standard deviation of ≤ 5 mg/dl. In the clinical accuracy study, 100% of measurements <75 mg/dl (4.2 mmol/liter) were within ± 15 mg/dl (0.8 mmol/liter) of reference value, and 99.6% of measurements ≥ 75 mg/dl (4.2 mmol/liter) were within ±20%. Patients were able to use the BGMS appropriately and evaluated it as easy to use. Acceptance of the SelectSimple BGMS was within predefined limits.

CONCLUSIONS

In these studies, the SelectSimple BGMS met all criteria for precision, system, and user accuracy, was easy to use, and was well accepted by patients.

Age and the purchase of prescription drug insurance by older adults

The Medicare Part D Prescription Drug Program places an unprecedented degree of choice in the hands of older adults despite concerns over their ability to make effective decisions and desire to have extensive choice in this context. While previous research has compared older adults to younger adults along these dimensions, our study, in contrast, examines how likelihood to delay decision making and preferences for choice differ by age among older age cohorts. Our analysis is based on responses of older adults to a simulation of enrollment in Medicare Part D. We examine how age, numeracy, cognitive reflection, and the interaction between age and performance on these instruments are related to the decision to enroll in a Medicare prescription drug plan and preference for choice in this context. We find that numeracy and cognitive reflection are positively associated with enrollment likelihood and that they are more important determinants of enrollment than age. We also find that greater numeracy is associated with a lower willingness to pay for choice. Hence, our findings raise concern that older adults, and, in particular, those with poorer numerical processing skills, may need extra support in enrolling in the program: they are less likely to enroll than those with stronger numerical processing skills, even though they show greater willingness to pay for choice.

Numeracy as a precursor to pro-social behavior: The impact of numeracy and presentation format on the cognitive mechanisms underlying donation decisions

Donation requests often convey numerical information about the people in need. In two studies we investigated the effects of numeracy and presentation format on the underlying affective and cognitive mechanisms of donation decisions. In Study 1, participants were presented with information about a victim in need, either in a frequency format or in a percentage format. In Study 2, we manipulated the identifiability and number of target victims. Our results demonstrate that donations of individuals lower in numeracy were more susceptible to changes in numeric presentation format than those higher in numeracy. Importantly, the underlying mechanisms for donations differed by numeracy. Whereas the mental image of the victim influenced donation decisions of less numerate people only, the estimated impact of a donation was positively correlated with donation amounts for both more and less numerate individuals.

Dual Processes in Decision Making and Developmental Neuroscience: A Fuzzy-Trace Model

From Piaget to the present, traditional and dual-process theories have predicted improvement in reasoning from childhood to adulthood, and improvement has been observed. However, developmental reversals-that reasoning biases emerge with development -have also been observed in a growing list of paradigms. We explain how fuzzy-trace theory predicts both improvement and developmental reversals in reasoning and decision making. Drawing on research on logical and quantitative reasoning, as well as on risky decision making in the laboratory and in life, we illustrate how the same small set of theoretical principles apply to typical neurodevelopment, encompassing childhood, adolescence, and adulthood, and to neurological conditions such as autism and Alzheimer's disease. For example, framing effects-that risk preferences shift when the same decisions are phrases in terms of gains versus losses-emerge in early adolescence as gist-based intuition develops. In autistic individuals, who rely less on gist-based intuition and more on verbatim-based analysis, framing biases are attenuated (i.e., they outperform typically developing control subjects). In adults, simple manipulations based on fuzzy-trace theory can make framing effects appear and disappear depending on whether gist-based intuition or verbatim-based analysis is induced. These theoretical principles are summarized and integrated in a new mathematical model that specifies how dual modes of reasoning combine to produce predictable variability in performance. In particular, we show how the most popular and extensively studied model of decision making-prospect theory-can be derived from fuzzy-trace theory by combining analytical (verbatim-based) and intuitive (gist-based) processes.

Physicians' Perceptions of Patients' Knowledge and Opinions Regarding Breast Cancer: Associations with Patient Education and Physician Numeracy

SUMMARY: Background: The aim of this study was to assess physicians' perception of their patients' knowledge and opinions regarding regular screening, and the association of their perceptions with physician numeracy and patient education level. Methods: We carried out a survey study of 240 obstetrician-gynecologists. Results: Overall, 99.6% physicians perceive that their patients know that breast cancer is hereditary, 86.5% predicted that there is a gene mutation related to breast cancer, and 79.4% predicted that most breast cancer cases occur in women aged 50 years or greater. Physicians with less educated patients thought that their patients would not know about genetic screening, and physicians with more educated patients thought that their patients would know that mammography does not reduce the risk of getting breast cancer. A total of 66.0% of obstetrician-gynecologists answered all 3 numeracy questions correctly. Less numerate physicians were more likely to indicate that their typical patient would agree with the statement about regular mammography screens than the more numerate physicians. Conclusions: Obstetrician-gynecologists expect that their patients know some things about breast cancer and not others. Some of the physicians' perceptions about patients differ based on numeracy.

Creating Compact Comparative Health Care Information

Background. The recent emphasis on providing comparative health care data to the public has resulted in a large amount of online information. To focus on the most essential attributes, insight is needed into which attributes are actually considered by consumers. Objective. To assess which attributes of Dutch hospital performance information contribute most to consumers’ hospital choice for cataract and total hip or knee replacement surgery. Design. Two discrete-choice experiments were performed: one for cataract surgery and one for total hip or knee replacement surgery. Participants viewed hypothetical hospitals based on representative values for 10 attributes (e.g., distance to the hospital, waiting time for the surgery, conduct of professionals, information provision, complication rate) and were asked to select the hospital they would choose if they needed treatment. We used multilevel logistic regression analysis to test the effects of the attributes and the interactions between attributes and respondent characteristics on consumers’ hospital choice. Results. All except one attribute (length of the first appointment with the ophthalmologist) contributed significantly to consumers’ choices. Although some differences were found between cataract and hip/knee replacement surgery, the most influential attributes for both types of surgeries were distance, waiting time, and the attributes of patient safety (complication rate of capsular rupture and the use of procedures to prevent adverse effects of thrombosis). Interaction effects were found between hospital attributes, on one hand, and age, education, and consumer choice orientation, on the other hand. Conclusions. As for cataract and total hip/knee replacement surgery, the attributes that seem most important to consumers when choosing a hospital are access (waiting time and distance) and patient safety attributes.

Using plausible group sizes to communicate information about medical risks

OBJECTIVE

To make informed health decisions, patients must understand and recall risks, which often involve ratios with large denominators. Grasping the meaning of such numbers may be difficult, because of limited exposure to large groups of people in either our evolutionary history or daily life.

METHODS

In an experiment (n=98), we investigated whether medical risks are easier to understand and recall if their representation is based on small, evolutionarily plausible groups of people, and whether this representation especially helps patients with low numeracy.

RESULTS

Participants-especially those with low numeracy-often disregarded and incorrectly recalled denominators of ratios representing medical risks when the denominators involved were large. Risks were easier to understand and recall if their representation was based on smaller, evolutionarily plausible groups of people.

CONCLUSIONS

Our results extend previous literature on the role of numeracy in understanding health-relevant risk communications by showing the importance of using plausible group sizes to communicate these risks to people with low numeracy. Our results also support the notion that problems in risk perception occur because of inappropriate presentation formats rather than cognitive biases.

PRACTICE IMPLICATIONS

Our findings suggest suitable ways to communicate quantitative medical data-especially to people with low numeracy.

Consequences of age-related cognitive declines

Adult age differences in a variety of cognitive abilities are well documented, and many of those abilities have been found to be related to success in the workplace and in everyday life. However, increased age is seldom associated with lower levels of real-world functioning, and the reasons for this lab-life discrepancy are not well understood. This article briefly reviews research concerned with relations of age to cognition, relations of cognition to successful functioning outside the laboratory, and relations of age to measures of work performance and achievement. The final section discusses several possible explanations for why there are often little or no consequences of age-related cognitive declines in everyday functioning.

The meaning of numbers in health: exploring health numeracy in a Mexican-American population

BACKGROUND

Health numeracy can be defined as the ability to use numeric information in the context of health. The interpretation and application of numbers in health may vary across cultural groups.

OBJECTIVE

To explore the construct of health numeracy among persons who identify as Mexican American.

DESIGN

Qualitative focus group study. Groups were stratified by preferred language and level of education. Audio-recordings were transcribed and Spanish groups (n = 3) translated to English. An analysis was conducted using principles of grounded theory.

PARTICIPANTS

A purposeful sample of participants from clinical and community sites in the Milwaukee and Chicago metropolitan areas.

MAIN MEASURES

A theoretical framework of health numeracy was developed based upon categories and major themes that emerged from the analysis.

KEY RESULTS

Six focus groups were conducted with 50 participants. Initial agreement in coding was 59-67% with 100% reached after reconciliation by the coding team. Three major themes emerged: 1) numeracy skills are applied to a broad range of communication and decision making tasks in health, 2) affective and cognitive responses to numeric information influence use of numbers in the health setting, and 3) there exists a strong desire to understand the meaning behind numbers used in health. The findings informed a theoretical framework of health numeracy.

CONCLUSIONS

Numbers are important across a range of skills and applications in health in a sample of an urban Mexican-American population. This study expands previous work that strives to understand the application of numeric skills to medical decision making and health behaviors.

The effect of numeracy on the comprehension of information about medicines in users of a patient information website

OBJECTIVE

To investigate the relationship between numeracy and the accuracy of side effect risk estimation following the presentation of information about a medicine via the Cancer Research UK (CR-UK) patient information website.

METHODS

591 website users were presented with information in different formats about the risks of side effects from taking tamoxifen. Participants estimated the risk of each side effect, provided other subjective ratings about the information and completed a numeracy task.

RESULTS

Regardless of presentation format, numeracy was correlated with the accuracy of three side effect risk estimates. People with cancer and tamoxifen users showed stronger correlations for all side effect estimates. In addition, numeracy was positively related to the perceived influence of the information on the decision to take the medicine and was negatively related to ratings of satisfaction with the information.

CONCLUSION

People with a lower numeracy level make larger errors in interpreting medicines side effect risk information.

PRACTICE IMPLICATIONS

Pharmacists, other health professionals and patient information websites should ensure they provide clear explanations of risk, particularly to people with low numeracy, and assess their understanding of those explanations. Future research into risk communication should take account of numeracy level, to investigate the impact of different formats.

Consumers' interpretation and use of comparative information on the quality of health care: the effect of presentation approaches

BACKGROUND

Public reports about health-care quality have not been effectively used by consumers thus far. A possible explanation is inadequate presentation of the information.

OBJECTIVE

To assess which presentation features contribute to consumers' correct interpretation and effective use of comparative health-care quality information and to examine the influence of consumer characteristics.

DESIGN

Fictitious Consumer Quality Index (CQI) data on home care quality were used to construct experimental presentation formats of comparative information. These formats were selected using conjoint analysis methodology. We used multilevel regression analysis to investigate the effects of presenting bar charts and star ratings, ordering of the data, type of stars, number of stars and inclusion of a global rating.

SETTING AND PARTICIPANTS

Data were collected during 2 weeks of online questioning of 438 members of an online access panel.

RESULTS

Both presentation features and consumer characteristics (age and education) significantly affected consumers' responses. Formats using combinations of bar charts and stars, three stars, an alphabetical ordering of providers and no inclusion of a global rating supported consumers. The effects of the presentation features differed across the outcome variables.

CONCLUSIONS

Comparative information on the quality of home care is complex for consumers. Although our findings derive from an experimental situation, they provide several suggestions for optimizing the information on the Internet. More research is needed to further unravel the effects of presentation formats on consumer decision making in health care.

Passing years, changing fears? Conceptualizing and measuring risk perceptions for chronic disease in younger and middle-aged women

As is true for many behavioral theory constructs, no consensus exists on how best to measure perceived risk; therefore, it is unclear whether different measures of disease risk perception are conceptually equivalent and whether such measures are equally appropriate for people with different objective disease risk. To investigate these issues, we used four commonly utilized risk perception items (measuring beliefs about personal risk, others' risk, disease prevalence, and mortality) to assess susceptibility to cardiovascular disease, breast cancer, and lung cancer among 454 younger (ages 18-25) and 169 middle-aged (40-64) women. We examined age- and ethnicity-related differences in participants' responses to the items. We also used structural equation modeling to test whether these items reflect a multidimensional, disease-specific latent construct of risk perception; and to test whether consistency exists in participants' disease-specific risk perceptions. Despite differences in responses to individual items, hypothesized models of perceived risk fit both age groups, suggesting that risk perception can be conceptualized in younger and middle-aged women as a multidimensional construct that is specific to disease yet reflective of global risk-related beliefs.

How do family physicians communicate about cardiovascular risk? Frequencies and determinants of different communication formats

Background

Patients understand information about risk better if it is communicated in numerical or visual formats (e.g. graphs) compared to verbal qualifiers only. How frequently different communication formats are used in clinical primary care settings is unknown.

Methods

We collected socioeconomic and patient understanding data using questionnaires and audio-recorded consultations about cardiovascular disease risk. The frequencies of the communication formats were calculated and multivariate regression analysis of associations between communication formats, patient and general practitioner characteristics, and patient subjective understanding was performed.

Results

In 73% of 70 consultations, verbal qualifiers were used exclusively to communicate cardiovascular risk, compared to numerical (11%) and visual (16%) formats. Female GPs and female patient's gender were significantly associated with a higher use of verbal formats compared to visual formats (p = 0.001 and p = 0.039, respectively). Patient subjective understanding was significantly higher in visual counseling compared to verbal counseling (p = 0.001).

Conclusions

Verbal qualifiers are the most often used communication format, though recommendations favor numerical and visual formats, with visual formats resulting in better understanding than others. Also, gender is associated with the choice of communication format. Barriers against numerical and visual communication formats among GPs and patients should be studied, including gender aspects. Adequate risk communication should be integrated into physicians' education.

The Decision Making Individual Differences Inventory and guidelines for the study of individual differences in judgment and decision-making research

Individual differences in decision making are a topic of longstanding interest, but often yield inconsistent and contradictory results. After providing an overview of individual difference measures that have commonly been used in judgment and decision-making (JDM) research, we suggest that our understanding of individual difference effects in JDM may be improved by amending our approach to studying them. We propose four recommendations for improving the pursuit of individual differences in JDM research: a more systematic approach; more theory-driven selection of measures; a reduced emphasis on main effects in favor of interactions between individual differences and decision features, situational factors, and other individual differences; and more extensive communication of results (whether significant or null, published or unpublished). As a first step, we offer our database—the Decision Making Individual Differences Inventory (DMIDI; http://html://www.sjdm.org/dmidi), a free, public resource that categorizes and describes the most common individual difference measures used in JDM research.

The influence of narrative v. statistical information on perceiving vaccination risks

BACKGROUND

Health-related information found on the Internet is increasing and impacts patient decision making, e.g. regarding vaccination decisions. In addition to statistical information (e.g. incidence rates of vaccine adverse events), narrative information is also widely available such as postings on online bulletin boards. Previous research has shown that narrative information can impact treatment decisions, even when statistical information is presented concurrently.

OBJECTIVES

As the determinants of this effect are largely unknown, we will vary features of the narratives to identify mechanisms through which narratives impact risk judgments.

METHODS

An online bulletin board setting provided participants with statistical information and authentic narratives about the occurrence and nonoccurrence of adverse events. Experiment 1 followed a single factorial design with 1, 2, or 4 narratives out of 10 reporting adverse events. Experiment 2 implemented a 2 (statistical risk 20% vs. 40%) × 2 (2/10 vs. 4/10 narratives reporting adverse events) × 2 (high vs. low richness) × 2 (high vs. low emotionality) between-subjects design. Dependent variables were perceived risk of side-effects and vaccination intentions.

RESULTS

Experiment 1 shows an inverse relation between the number of narratives reporting adverse-events and vaccination intentions, which was mediated by the perceived risk of vaccinating. Experiment 2 showed a stronger influence of the number of narratives than of the statistical risk information. High (vs. low) emotional narratives had a greater impact on the perceived risk, while richness had no effect.

IMPLICATIONS

The number of narratives influences risk judgments can potentially override statistical information about risk.

The association of understanding of medical statistics with health information seeking and health provider interaction in a national sample of young adults

Numeracy, or, "the ability to use and understand numbers in daily life" is a critical component of health literacy. However, little research has focused on numeracy in young adults (ages 18-29). We used a national sample to examine how health-information seeking, trust in sources, and interactions with health care providers differ for young adults with lower and higher numeracy. We included respondents ages 18 to 29 (n = 661) from the latest administration (2008) of the Health Information National Trends Survey (HINTS). There were no significant differences between those with lower and higher numeracy for most sociodemographic variables, nor did numeracy predict trust in health information sources. However, there were several differences for health-information seeking and health-provider interactions. Those with lower numeracy were significantly more likely to say their most recent search took a lot of effort (46% vs. 24%, p = .0008) and was frustrating (45% vs. 22%, p = .0038). Those in the lower numeracy group also reported more negative interactions with health providers, including feeling less able to rely on their provider (62% vs. 86%, p < .0001), and less likely to say their provider made sure they understood information (70% vs. 88%, p = .0001) and helped with any uncertainty (51% vs. 75%, p < .0001), even when adjusting for other variables. Our data suggest that limited comfort with numbers and statistics can influence a variety of health-related factors for young adults. More research is needed to understand how health literacy skills--including numeracy--influence health-information seeking, patient-provider relationships, and health outcomes, for young adults.

How to reduce the effect of framing on messages about health

BACKGROUND

Patients must be informed about risks before any treatment can be implemented. Yet serious problems in communicating these risks occur because of framing effects.

OBJECTIVE

To investigate the effects of different information frames when communicating health risks to people with high and low numeracy and determine whether these effects can be countered or eliminated by using different types of visual displays (i.e., icon arrays, horizontal bars, vertical bars, or pies).

DESIGN

Experiment on probabilistic, nationally representative US (n = 492) and German (n = 495) samples, conducted in summer 2008.

OUTCOME MEASURES

Participants' risk perceptions of the medical risk expressed in positive (i.e., chances of surviving after surgery) and negative (i.e., chances of dying after surgery) terms.

KEY RESULTS

Although low-numeracy people are more susceptible to framing than those with high numeracy, use of visual aids is an effective method to eliminate its effects. However, not all visual aids were equally effective: pie charts and vertical and horizontal bars almost completely removed the effect of framing. Icon arrays, however, led to a smaller decrease in the framing effect.

CONCLUSIONS

Difficulties with understanding numerical information often do not reside in the mind, but in the representation of the problem.