Paul K. J. Han

How Numeracy Influences Risk Comprehension and Medical Decision Making

We review the growing literature on health numeracy, the ability to understand and use numerical information, and its relation to cognition, health behaviors, and medical outcomes. Despite the surfeit of health information from commercial and noncommercial sources, national and international surveys show that many people lack basic numerical skills that are essential to maintain their health and make informed medical decisions. Low numeracy distorts perceptions of risks and benefits of screening, reduces medication compliance, impedes access to treatments, impairs risk communication (limiting prevention efforts among the most vulnerable), and, based on the scant research conducted on outcomes, appears to adversely affect medical outcomes. Low numeracy is also associated with greater susceptibility to extraneous factors (i.e., factors that do not change the objective numerical information). That is, low numeracy increases susceptibility to effects of mood or how information is presented (e.g., as frequencies vs. percentages) and to biases in judgment and decision making (e.g., framing and ratio bias effects). Much of this research is not grounded in empirically supported theories of numeracy or mathematical cognition, which are crucial for designing evidence-based policies and interventions that are effective in reducing risk and improving medical decision making. To address this gap, we outline four theoretical approaches (psychophysical, computational, standard dual-process, and fuzzy trace theory), review their implications for numeracy, and point to avenues for future research.

Varieties of uncertainty in health care: a conceptual taxonomy.

Uncertainty is a pervasive and important problem that has attracted increasing attention in health care, given the growing emphasis on evidence-based medicine, shared decision making, and patient-centered care. However, our understanding of this problem is limited, in part because of the absence of a unified, coherent concept of uncertainty. There are multiple meanings and varieties of uncertainty in health care that are not often distinguished or acknowledged although each may have unique effects or warrant different courses of action. The literature on uncertainty in health care is thus fragmented, and existing insights have been incompletely translated to clinical practice. This article addresses this problem by synthesizing diverse theoretical and empirical literature from the fields of communication, decision science, engineering, health services research, and psychology and developing a new integrative conceptual taxonomy of uncertainty. A 3-dimensional taxonomy is proposed that characterizes uncertainty in health care according to its fundamental sources, issues, and locus. It is shown how this new taxonomy facilitates an organized approach to the problem of uncertainty in health care by clarifying its nature and prognosis and suggesting appropriate strategies for its analysis and management.

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

BackgroundMaking evidence-based decisions often requires comparison of two or more options. Research-based evidence may exist which quantifies how likely the outcomes are for each option. Understanding these numeric estimates improves patients’ risk perception and leads to better informed decision making. This paper summarises current “best practices” in communication of evidence-based numeric outcomes for developers of patient decision aids (PtDAs) and other health communication tools.MethodAn expert consensus group of fourteen researchers from North America, Europe, and Australasia identified eleven main issues in risk communication. Two experts for each issue wrote a “state of the art” summary of best evidence, drawing on the PtDA, health, psychological, and broader scientific literature. In addition, commonly used terms were defined and a set of guiding principles and key messages derived from the results.ResultsThe eleven key components of risk communication were: 1) Presenting the chance an event will occur; 2) Presenting changes in numeric outcomes; 3) Outcome estimates for test and screening decisions; 4) Numeric estimates in context and with evaluative labels; 5) Conveying uncertainty; 6) Visual formats; 7) Tailoring estimates; 8) Formats for understanding outcomes over time; 9) Narrative methods for conveying the chance of an event; 10) Important skills for understanding numerical estimates; and 11) Interactive web-based formats. Guiding principles from the evidence summaries advise that risk communication formats should reflect the task required of the user, should always define a relevant reference class (i.e., denominator) over time, should aim to use a consistent format throughout documents, should avoid “1 in x” formats and variable denominators, consider the magnitude of numbers used and the possibility of format bias, and should take into account the numeracy and graph literacy of the audience.ConclusionA substantial and rapidly expanding evidence base exists for risk communication. Developers of tools to facilitate evidence-based decision making should apply these principles to improve the quality of risk communication in practice.

Differences Between Primary Care Physicians’ and Oncologists’ Knowledge, Attitudes and Practices Regarding the Care of Cancer Survivors

BackgroundThe growing number of cancer survivors combined with a looming shortage of oncology specialists will require greater coordination of post-treatment care responsibilities between oncologists and primary care physicians (PCPs). However, data are limited regarding these physicians’ views of cancer survivors’ care.ObjectiveTo compare PCPs and oncologists with regard to their knowledge, attitudes, and practices for follow-up care of breast and colon cancer survivors.Design and SubjectsMailed questionnaires were completed by a nationally representative sample of 1,072 PCPs and 1,130 medical oncologists in 2009 (cooperation rate = 65%). Sampling and non-response weights were used to calculate estimates to reflect practicing US PCPs and oncologists.Main MeasuresPCPs and oncologists reported their 1) preferred model for delivering cancer survivors’ care; 2) assessment of PCPs’ ability to perform follow-up care tasks; 3) confidence in their knowledge; and 4) cancer surveillance practices.Key ResultsCompared with PCPs, oncologists were less likely to believe PCPs had the skills to conduct appropriate testing for breast cancer recurrence (59% vs. 23%, P < 0.001) or to care for late effects of breast cancer (75% vs. 38%, P < 0.001). Only 40% of PCPs were very confident of their own knowledge of testing for recurrence. PCPs were more likely than oncologists to endorse routine use of non-recommended blood and imaging tests for detecting cancer recurrence, with both groups departing substantially from guideline recommendations.ConclusionThere are significant differences in PCPs’ and oncologists’ knowledge, attitudes, and practices with respect to care of cancer survivors. Improving cancer survivors’ care may require more effective communication between these two groups to increase PCPs’ confidence in their knowledge, and must also address oncologists’ attitudes regarding PCPs’ ability to care for cancer survivors.

Impact of cancer on health-related quality of life of older Americans.

BACKGROUND The impact of cancer on health-related quality of life (HRQOL) is poorly understood because of the lack of baseline HRQOL status before cancer diagnosis. To our knowledge, this is the first population-based study to quantify the nature and extent of HRQOL changes from before to after cancer diagnosis for nine types of cancer patients and to compare their health with individuals without cancer. METHODS The Surveillance, Epidemiology, and End Results cancer registry data were linked with the Medicare Health Outcomes Survey (MHOS) data; data were collected from Medicare beneficiaries who were aged 65 years and older from 1998 through 2003. Cancer patients (n = 1432; with prostate, breast, colorectal, lung, bladder, endometrial, or kidney cancers; melanoma; or non-Hodgkin lymphoma [NHL]) were selected whose first cancer diagnosis occurred between their baseline and follow-up MHOS assessments. Control subjects without cancer (n = 7160) were matched to cancer patients by use of propensity scores that were estimated from demographics and comorbid medical conditions. Analysis of covariance models were used to estimate changes in HRQOL as assessed with the Medical Outcomes Study Short Form-36 survey (mean score = 50, SD = 10). All statistical tests were two-sided. RESULTS Patients with all cancer types (except melanoma and endometrial cancer) reported statistically significant declines in physical health (mean scores: prostate cancer = -3.4, 95% confidence interval [CI] = -2.5 to -4.2; breast cancer = -3.5, 95% CI = -2.5 to -4.5; bladder cancer = -4.3, 95% CI = -2.5 to -6.1; colorectal cancer = -4.4, 95% CI = -3.3 to -5.5; kidney cancer = -5.7, 95% CI = -3.2 to -8.2; NHL = -6.7, 95% CI = -4.4 to -9.1; and lung cancer = -7.5, 95% CI = -5.9 to -9.2) compared with the control subjects (mean score = -1.8, 95% CI = -1.6 to -2.0) (all P < .05). However, only lung (mean score = -5.4, 95% CI = -3.5 to -7.2), colorectal (mean score = -3.5, 95% CI = -2.2 to -4.7), and prostate (mean score = -2.8, 95% CI = -1.8 to -3.7) cancer patients showed statistically significant decreases in mental health relative to the mean change of the control subjects (mean score = -1.2, 95% CI = -0.9 to -1.4) (all P < .05). CONCLUSION These findings provide validation of the specific deleterious effects of cancer on HRQOL and an evidence base for future research and clinical interventions aimed at understanding and remediating these effects.

Prevalence of Tamoxifen Use for Breast Cancer Chemoprevention Among U.S. Women

Background: Tamoxifen can reduce the risk of developing invasive estrogen receptor–positive breast cancer by 49%, but it is unknown how many women in the United States are taking tamoxifen for primary prevention of breast cancer. Methods: Data from the years 2000 and 2005 National Health Interview Surveys were analyzed to estimate the prevalence of tamoxifen use among U.S. women for primary chemoprevention of breast cancer. Results: In 2000, ∼0.2% of U.S. women ages 40 to 79 years without a personal history of breast cancer took tamoxifen for chemoprevention (95% confidence interval, 0.13-0.31). In 2005, the prevalence was ∼0.08% (95% confidence interval, 0.03-0.17). Conclusion: The prevalence of tamoxifen use for primary prevention of breast cancer was very low in the years 2000 and 2005. Possible explanations for the low uptake are explored. Cancer Epidemiol Biomarkers Prev; 19(2); 443–6

Rethinking the Objectives of Decision Aids: A Call for Conceptual Clarity

Health decision aids are a potentially valuable adjunct to patient-physician communication and decision making. Although the overarching goal of decision aids— to help patients make informed, preference-sensitive choices—is widely accepted, experts do not agree on the means to achieve this end. In this article, the authors critically examine the theoretical basis and appropriateness of 2 widely accepted criteria used to evaluate decision aids: values clarification and reduction of decisional conflict. First, they argue that although clarifying values is central to decision making under uncertainty, it is not clear that decision aids—as they have been conceived and operationalized so far—can and should be used to achieve this goal. The pursuit of clarifying values, particularly values clarification exercises, raises a number of ethical, methodological, and conceptual issues, and the authors suggest research questions that should be addressed before values clarification is routinely endorsed. Second, the authors argue that the goal of reducing decisional conflict is conceptually untenable and propose that it be eliminated as an objective of decision aids.

Perceived Ambiguity About Cancer Prevention Recommendations: Relationship to Perceptions of Cancer Preventability, Risk, and Worry

In this study, we apply the concept of “ambiguity,” as developed in the decision theory literature, to an analysis of potential psychological consequences of uncertainty about cancer prevention recommendations. We used Health Information National Trends Survey (HINTS) 2003 data to examine how perceived ambiguity about cancer prevention recommendations relates to three other cognitive variables known to influence cancer-protective behavior: perceived cancer preventability, perceived cancer risk, and cancer-related worry. Using logistic regression analyses, we tested several predictions derived from a review of literature on the effects of ambiguity perceptions on decision making, cognitions, and emotions. We found perceived ambiguity to have a strong negative relationship with perceived cancer preventability, consistent with “ambiguity aversion”—a pessimistic bias in the interpretation of ambiguity. Cancer worry moderated this relationship; ambiguity aversion increased with higher levels of worry. At the same time, perceived ambiguity was positively related to both perceived cancer risk and cancer worry. Furthermore, perceived risk partially mediated the relationship between perceived ambiguity and worry. These findings suggest that perceived ambiguity about cancer prevention recommendations may have broad and important effects on other health cognitions. We discuss ethical implications of these findings for health communication efforts, and propose a tentative causal model to guide future research.

Perceived ambiguity about cancer prevention recommendations: associations with cancer-related perceptions and behaviours in a US population survey

Background  Health information reaching the public today is often characterized by what decision theorists have termed ‘ambiguity’– i.e. uncertainty regarding the information’s reliability, credibility or adequacy. This is a critical problem, as growing research suggests that ambiguity has important effects–promoting pessimistic judgments about risks and potential outcomes of risk‐reducing behaviours, and lowering adoption of these behaviours. However, little is known about the public’s perceptions of ambiguity in the health information domain, the effects of these perceptions, and the factors that influence these effects.

Breast Cancer Screening Beliefs, Recommendations, and Practices Primary Care Physicians in the United States

Primary care physicians (PCPs) play a key role in breast cancer screening, yet no current data exist regarding PCP practices.