Numeracy and Health: A Tyranny of Numbers

Numeracy (numeric literacy) is important to shared decision making in cancer because numbers instruct, inform, and give meaning to information about cancer risks, screening, medications, and other treatments. Numeracy levels in the U.S., however, are limited, and many patients are innumerate.

This topic is critical to cancer decisions because innumeracy is linked with health disparities and because trends exist to involve consumers and patients more in health decisions. These trends are part of a recent emphasis in health policy to tap the potential power of informed consumers to improve individual and societal outcomes. However, because not all consumers have the ability to use complex and often numeric health information, the combination of policy shifts with skill differences may result in ever greater health disparities as those with more skills take advantage of the information-rich environment while those with fewer skills fall further behind.

This possibility is consistent with the data that show less numerate individuals experiencing worse health outcomes from having higher blood sugar levels if diabetic, having children who are more likely to be over- or under-weight, and being less successful in following complex medication regimens. These outcomes are linked with differences in how people who differ in numeracy make decisions. In particular, the less numerate tend to make worse decisions, relying more on suboptimal heuristics or mental shortcuts in judgment and choice. They are also more susceptible to the power of experience and emotions as well as to how information is framed. The highly numerate, on the other hand, understand numbers better, and they draw more affective meaning from them in ways that allow numeric information about cancer risks to be used more effectively.

The psychological mechanisms underlying these numeracy-related, decision-making differences point towards better ways of presenting numeric information about health risks and benefits so that all individuals can take part in shared decision making more effectively. Although patients are not always adept at using the complex often numeric information important to making good health decisions, we know a lot about evidence-based communication techniques. Four evidence-based strategies will be discussed. Patient decision making should be done strategically, taking advantage of these strategies to maximize communication effectiveness in cancer.