Increasingly over the past decade, health literacy researchers and practitioners have been turning their attention to issues of numeracy, recognizing that numeric tasks related to a wide array of health activities have not been sufficiently examined or addressed. Numbers are a vital part of health discussions and play a key role in health decisions and actions. People must grapple with numbers on food and medicine labels, insurance forms, enrollment documents, weather charts, and allergy alerts. They are expected to understand a test result or vital-sign measure in the context of a normal range. They are challenged to undertake risk-benefit analyses for critical decisions. Numbers are important for health action and for health decisions but frequently get in the way for many adults and confound rather than provide assistance.
Interest in health numeracy has been spurred by the various waves of literacy and numeracy surveys examining the skills of adults in industrialized nations. The most recent assessment, conducted by the Organisation for Economic Co-operation and Development (OECD), was the PIAAC Survey of Adult Skills in 2011. Findings indicated that a small percentage of U.S. adults placed in the highest levels of numeracy skills and almost one-third of U.S. adults scored in the bottom two levels. People whose skills are at the lower levels can use whole numbers but may struggle with calculations using percentages and with abstract numerical concepts, such as risk. Analyses of findings indicate that a significant proportion of the U.S adult population do not have sufficient numeracy skills to meet many of the demands and expectations of modern life.