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A Definition and Operational Framework for Health Numeracy
Editorials and Commentary
A Definition and Operational Framework for Health Numeracy Amanda L. Golbeck, PhD, Carolyn R. Ahlers-Schmidt, PhD, Angelia M. Paschal, PhD, S. Edwards Dismuke, MD, MSPH Abstract
Health numeracy has often been overshadowed by health literacy, either ignored completely or identified simply as a subset of health literacy. Only now are researchers beginning to realize the importance of health numeracy as a separate entity. One of the first steps in this evolution is to establish a distinct definition for health numeracy, something that has not been addressed in the literature to date. This paper proposes such a definition, as well as a set of clarifying categories in hopes of helping researchers both to advance the field of health numeracy and to focus their topics within the realm of health numeracy. (Am J Prev Med 2005;29(4):375–376) © 2005 American Journal of Preventive Medicine
Introduction
T
he purpose of this commentary is to offer a definition and operational framework for the concept of “health numeracy.” Health numeracy is a relatively new field, and dissemination of empirical support for its importance is very recent. Most health numeracy studies have focused on risk relationships1– 6 and not on outcomes. However, one important outcome study has been done. Estrada et al.7 administered a six-item questionnaire to measure health numeracy; findings suggested that 82.5% of participants missed two or more of the six questions. Further, during a 3-month follow-up, findings indicated that patients with lower numeracy skills had poorer health outcomes related to anticoagulation control. There is a critical need for additional studies relating health numeracy to health outcomes, and perhaps development of a clear definition of health numeracy will help stimulate the development of such studies. While the published literature contains multiple definitions of health literacy,7–12 and it also contains multiple definitions of “numeracy,”13,14 there is no definition of health numeracy to be found as a keystone of the growing body of literature in this area.15 The definition of health numeracy offered here merges aspects of the Healthy People 2010 definition of health literacy with Evans’14 general definition of numeracy. Health numeracy is the degree to which individuals have the capacity to access, process, interpret, commuFrom the office of Research (Golbeck, Ahlers-Schmidt), and Preventive Medicine and Public Health (Paschal, Dismuke), University of Kansas School of Medicine-Wichita, Wichita, Kansas Address correspondence and reprint requests to: Carolyn R. Ahlers-Schmidt, PhD, Office of Research, University of Kansas School of Medicine-Wichita, 1010 N. Kansas, Wichita KS 67214. E-mail: [email protected].
nicate, and act on numerical, quantitative, graphical, biostatistical, and probabilistic health information needed to make effective health decisions. This definition acknowledges the continuum of degrees of health numeracy over the simple distinction of being functional or not. It also emphasizes that health numeracy is not simply about understanding (processing and interpreting), but also functioning (communicating and acting) on numeric concepts in terms of health. Degrees of health numeracy may be operationalized in four functional categories: basic, computational, analytical, and statistical. The purpose of the four categories, described below, is to address numeracy skills that the general public should have in order to function in today’s healthcare system. Basic health numeracy involves sufficient basic skills to identify numbers, and make sense of quantitative data requiring no manipulation of numbers. Examples include identifying the appropriate number of pills to take from a prescription bottle, the date and time of a doctor’s appointment, and using a phone book to find a clinic’s phone number. Computational health numeracy involves the ability to count, quantify, compute, and otherwise use simple manipulation of numbers, quantities, items, or visual elements in a health context so as to function in everyday health situations. Examples include determining net carbohydrates based on information on a nutritional label or determining fees based on a sliding scale. Analytical health numeracy involves a higher level of literacy than the previous levels. It involves the ability to make sense of information, such as that presented in functional health numeracy, but also involves higherlevel concepts such as inference, estimation, propor-
Am J Prev Med 2005;29(4) © 2005 American Journal of Preventive Medicine • Published by Elsevier Inc.
0749-3797/05/$–see front matter doi:10.1016/j.amepre.2005.06.012
375
tions, percentages, frequencies, and equivalent situations. It often requires information to be pulled from multiple sources and in multiple formats. Examples of analytical health numeracy include determining whether cholesterol levels are within the normal range, understanding basic graphs, and comparing benefits from various insurance policies or programs. Statistical health numeracy involves an understanding of basic biostatistics involving probability statements, skills to compare information presented on different scales (probability, proportion, percent), the ability to critically analyze quantitative health information such as life expectancy and risk, and an understanding of statistical concepts such as randomization and a “blind” study. Examples of statistical health numeracy include determining preference of treatment based on probabilities of efficacy and side effects, interpreting complex graphs of health information, and making decisions based on relative versus absolute risk. The four categories of health numeracy should not be viewed as mutually exclusive, but rather as overlapping clusters of concepts defined by skill level, degree of manipulation, and the extent of literacy involved. They should also not be viewed as exhaustive beyond their stated purpose; for example, biostatistical skills beyond the statistical level are necessary for many who work in the health field or are involved in healthrelated research, but these are not included as a category because they are not necessary for the general public to function in today’s healthcare system. Finally, these categories are simply proposals for areas to help focus the field of health numeracy. Empirical research is needed to determine the appropriateness of these classifications within the health numeracy spectrum. Most existing definitions of health literacy fail to explicitly identify a numeracy component. Exceptions may be found among the most recent definitions, which explicitly identify “numerical tasks” within the definition.7,8,10 Simply addressing numerical tasks as a part of health literacy does not seem adequate in light of the inherent importance of conceptual and functional quantitative components of health care and health decisions.12 There is a need, for example, to also address health and numeracy concepts, visual communications such as graphs, and basic biostatistical information. Health numeracy is much broader than numerical tasks, making it difficult to productively incorporate into a definition of health literacy, and calling for a separate definition. According to Gazmararian et al.,16 “we must build a society where people can understand and act on health information,” and this includes numerical, quantitative, graphical, biostatistical, and probabilistic health infor-
376
mation. Defining health numeracy, and identifying functional categories, should focus needed attention to this area and stimulate future research on topics of manageable size. Suggestions for future research include the development of an assessment tool that addresses the four levels of health numeracy; the identification of populations appropriate for interventions at these levels; the development and assessment of efficacy of interventions to improve health numeracy at all levels; and finally, outcome studies to demonstrate the role of health numeracy on health outcomes. We are grateful to the peer reviewers who provided insightful suggestions for improvement of the final manuscript. No financial conflict of interest was reported by the authors of this paper.
References 1. Davids SL, Schapira MM, McAuliffe TL, Nattinger AB. Predictors of pessimistic breast cancer risk perceptions in a primary care population. J Gen Intern Med 2004;19:310 –5. 2. Gramling R, Irvin JE, Nash J, Sciamanna C, Culpepper L. Numeracy and medicine: key family physician attitudes about communicating probability with patients. J Am Board Fam Pract 2004;17:473. 3. Schapira MM, Davids SL, McAuliffe TL, Nattinger AB. Agreement between scales in the measurement of breast cancer risk perceptions. Risk Anal 2004;24:665–73. 4. Schwartz SR, McDowell J, Yueh B. Numeracy and the shortcomings of utility assessment in head and neck cancer patients. Head Neck. 2004;26:401–7. 5. Sheridan SL, Pignone MP, Lewis CL. A randomized comparison of patients’ understanding of number needed to treat and other common risk reduction formats. J Gen Intern Med 2003;18:884 –92. 6. Woloshin S, Schwartz LM, Moncur M, Gabriel S, Tosteson ANA. Assessing values for health: numeracy matters. Med Decis Making 2001;21:382–90. 7. Estrada C, Martin-Hryniewicz M, Peek BT, Collins C, Byrd JC. Literacy and numeracy skills and anticoagulation control. Am J Med Sci 2004;328:88 –93. 8. Ad Hoc Committee on Health Literacy for the Council on Scientific Affairs, American Medical Association. Health literacy: report of the Council on Scientific Affairs. JAMA 1999;281:552–7. 9. U.S. Department of Health and Human Services. Healthy people 2010: understanding and improving health. Washington DC: U.S. Department of Health and Human Services, 2000. 10. Berkman ND, DeWalt DA, Pignone MP, et al. Literacy and health outcomes. Rockville MD: Agency for Healthcare Research and Quality, January 2004 (prepared by RTI International–University of North Carolina Evidence-Based Practice Center under contract 290-02-0016; AHRQ publication 04-E007-2). 11. Nurss JR, Parker RM, Williams MV, Baker DW. Test of Functional Health Literacy in Adults (TOFHLA). Atlanta: Georgia State University, 1995. 12. Parker RM, Baker DW, Williams MV, Nurss JR. The Test of Functional Health Literacy in Adults: a new instrument for measuring patients’ literacy skills. J Gen Intern Med 1995;10:537– 41. 13. Coben D, Colwell D, Macrae S, Boaler J, Brown M, Rhodes V. Adult numeracy: review of research and related literature. London: National Research and Development Centre for Adult Literacy and Numeracy, November 2003. 14. Evans J. Adults’ mathematical thinking and emotions: a study of numerate practices. London: Routledge/Falmer, Taylor and Francis Group, 2000. 15. Golbeck AL, Ahlers-Schmidt CR, Paschal AM, Dismuke SE. Health numeracy in adults: an overview and annotated bibliography. Wichita KS: Kansas University School of Medicine-Wichita, 2005. 16. Gazmararian JA, Curran JW, Parker RM, Bernhardt JM, Debuono BA. Public health literacy in America: an ethical imperative. Am J Prev Med 2005;28:317–22.
American Journal of Preventive Medicine, Volume 29, Number 4
A Definition and Operational Framework for Health Numeracy Amanda L. Golbeck, PhD, Carolyn R. Ahlers-Schmidt, PhD, Angelia M. Paschal, PhD, S. Edwards Dismuke, MD, MSPH Abstract
Health numeracy has often been overshadowed by health literacy, either ignored completely or identified simply as a subset of health literacy. Only now are researchers beginning to realize the importance of health numeracy as a separate entity. One of the first steps in this evolution is to establish a distinct definition for health numeracy, something that has not been addressed in the literature to date. This paper proposes such a definition, as well as a set of clarifying categories in hopes of helping researchers both to advance the field of health numeracy and to focus their topics within the realm of health numeracy. (Am J Prev Med 2005;29(4):375–376) © 2005 American Journal of Preventive Medicine
Introduction
T
he purpose of this commentary is to offer a definition and operational framework for the concept of “health numeracy.” Health numeracy is a relatively new field, and dissemination of empirical support for its importance is very recent. Most health numeracy studies have focused on risk relationships1– 6 and not on outcomes. However, one important outcome study has been done. Estrada et al.7 administered a six-item questionnaire to measure health numeracy; findings suggested that 82.5% of participants missed two or more of the six questions. Further, during a 3-month follow-up, findings indicated that patients with lower numeracy skills had poorer health outcomes related to anticoagulation control. There is a critical need for additional studies relating health numeracy to health outcomes, and perhaps development of a clear definition of health numeracy will help stimulate the development of such studies. While the published literature contains multiple definitions of health literacy,7–12 and it also contains multiple definitions of “numeracy,”13,14 there is no definition of health numeracy to be found as a keystone of the growing body of literature in this area.15 The definition of health numeracy offered here merges aspects of the Healthy People 2010 definition of health literacy with Evans’14 general definition of numeracy. Health numeracy is the degree to which individuals have the capacity to access, process, interpret, commuFrom the office of Research (Golbeck, Ahlers-Schmidt), and Preventive Medicine and Public Health (Paschal, Dismuke), University of Kansas School of Medicine-Wichita, Wichita, Kansas Address correspondence and reprint requests to: Carolyn R. Ahlers-Schmidt, PhD, Office of Research, University of Kansas School of Medicine-Wichita, 1010 N. Kansas, Wichita KS 67214. E-mail: [email protected].
nicate, and act on numerical, quantitative, graphical, biostatistical, and probabilistic health information needed to make effective health decisions. This definition acknowledges the continuum of degrees of health numeracy over the simple distinction of being functional or not. It also emphasizes that health numeracy is not simply about understanding (processing and interpreting), but also functioning (communicating and acting) on numeric concepts in terms of health. Degrees of health numeracy may be operationalized in four functional categories: basic, computational, analytical, and statistical. The purpose of the four categories, described below, is to address numeracy skills that the general public should have in order to function in today’s healthcare system. Basic health numeracy involves sufficient basic skills to identify numbers, and make sense of quantitative data requiring no manipulation of numbers. Examples include identifying the appropriate number of pills to take from a prescription bottle, the date and time of a doctor’s appointment, and using a phone book to find a clinic’s phone number. Computational health numeracy involves the ability to count, quantify, compute, and otherwise use simple manipulation of numbers, quantities, items, or visual elements in a health context so as to function in everyday health situations. Examples include determining net carbohydrates based on information on a nutritional label or determining fees based on a sliding scale. Analytical health numeracy involves a higher level of literacy than the previous levels. It involves the ability to make sense of information, such as that presented in functional health numeracy, but also involves higherlevel concepts such as inference, estimation, propor-
Am J Prev Med 2005;29(4) © 2005 American Journal of Preventive Medicine • Published by Elsevier Inc.
0749-3797/05/$–see front matter doi:10.1016/j.amepre.2005.06.012
375
tions, percentages, frequencies, and equivalent situations. It often requires information to be pulled from multiple sources and in multiple formats. Examples of analytical health numeracy include determining whether cholesterol levels are within the normal range, understanding basic graphs, and comparing benefits from various insurance policies or programs. Statistical health numeracy involves an understanding of basic biostatistics involving probability statements, skills to compare information presented on different scales (probability, proportion, percent), the ability to critically analyze quantitative health information such as life expectancy and risk, and an understanding of statistical concepts such as randomization and a “blind” study. Examples of statistical health numeracy include determining preference of treatment based on probabilities of efficacy and side effects, interpreting complex graphs of health information, and making decisions based on relative versus absolute risk. The four categories of health numeracy should not be viewed as mutually exclusive, but rather as overlapping clusters of concepts defined by skill level, degree of manipulation, and the extent of literacy involved. They should also not be viewed as exhaustive beyond their stated purpose; for example, biostatistical skills beyond the statistical level are necessary for many who work in the health field or are involved in healthrelated research, but these are not included as a category because they are not necessary for the general public to function in today’s healthcare system. Finally, these categories are simply proposals for areas to help focus the field of health numeracy. Empirical research is needed to determine the appropriateness of these classifications within the health numeracy spectrum. Most existing definitions of health literacy fail to explicitly identify a numeracy component. Exceptions may be found among the most recent definitions, which explicitly identify “numerical tasks” within the definition.7,8,10 Simply addressing numerical tasks as a part of health literacy does not seem adequate in light of the inherent importance of conceptual and functional quantitative components of health care and health decisions.12 There is a need, for example, to also address health and numeracy concepts, visual communications such as graphs, and basic biostatistical information. Health numeracy is much broader than numerical tasks, making it difficult to productively incorporate into a definition of health literacy, and calling for a separate definition. According to Gazmararian et al.,16 “we must build a society where people can understand and act on health information,” and this includes numerical, quantitative, graphical, biostatistical, and probabilistic health infor-
376
mation. Defining health numeracy, and identifying functional categories, should focus needed attention to this area and stimulate future research on topics of manageable size. Suggestions for future research include the development of an assessment tool that addresses the four levels of health numeracy; the identification of populations appropriate for interventions at these levels; the development and assessment of efficacy of interventions to improve health numeracy at all levels; and finally, outcome studies to demonstrate the role of health numeracy on health outcomes. We are grateful to the peer reviewers who provided insightful suggestions for improvement of the final manuscript. No financial conflict of interest was reported by the authors of this paper.
References 1. Davids SL, Schapira MM, McAuliffe TL, Nattinger AB. Predictors of pessimistic breast cancer risk perceptions in a primary care population. J Gen Intern Med 2004;19:310 –5. 2. Gramling R, Irvin JE, Nash J, Sciamanna C, Culpepper L. Numeracy and medicine: key family physician attitudes about communicating probability with patients. J Am Board Fam Pract 2004;17:473. 3. Schapira MM, Davids SL, McAuliffe TL, Nattinger AB. Agreement between scales in the measurement of breast cancer risk perceptions. Risk Anal 2004;24:665–73. 4. Schwartz SR, McDowell J, Yueh B. Numeracy and the shortcomings of utility assessment in head and neck cancer patients. Head Neck. 2004;26:401–7. 5. Sheridan SL, Pignone MP, Lewis CL. A randomized comparison of patients’ understanding of number needed to treat and other common risk reduction formats. J Gen Intern Med 2003;18:884 –92. 6. Woloshin S, Schwartz LM, Moncur M, Gabriel S, Tosteson ANA. Assessing values for health: numeracy matters. Med Decis Making 2001;21:382–90. 7. Estrada C, Martin-Hryniewicz M, Peek BT, Collins C, Byrd JC. Literacy and numeracy skills and anticoagulation control. Am J Med Sci 2004;328:88 –93. 8. Ad Hoc Committee on Health Literacy for the Council on Scientific Affairs, American Medical Association. Health literacy: report of the Council on Scientific Affairs. JAMA 1999;281:552–7. 9. U.S. Department of Health and Human Services. Healthy people 2010: understanding and improving health. Washington DC: U.S. Department of Health and Human Services, 2000. 10. Berkman ND, DeWalt DA, Pignone MP, et al. Literacy and health outcomes. Rockville MD: Agency for Healthcare Research and Quality, January 2004 (prepared by RTI International–University of North Carolina Evidence-Based Practice Center under contract 290-02-0016; AHRQ publication 04-E007-2). 11. Nurss JR, Parker RM, Williams MV, Baker DW. Test of Functional Health Literacy in Adults (TOFHLA). Atlanta: Georgia State University, 1995. 12. Parker RM, Baker DW, Williams MV, Nurss JR. The Test of Functional Health Literacy in Adults: a new instrument for measuring patients’ literacy skills. J Gen Intern Med 1995;10:537– 41. 13. Coben D, Colwell D, Macrae S, Boaler J, Brown M, Rhodes V. Adult numeracy: review of research and related literature. London: National Research and Development Centre for Adult Literacy and Numeracy, November 2003. 14. Evans J. Adults’ mathematical thinking and emotions: a study of numerate practices. London: Routledge/Falmer, Taylor and Francis Group, 2000. 15. Golbeck AL, Ahlers-Schmidt CR, Paschal AM, Dismuke SE. Health numeracy in adults: an overview and annotated bibliography. Wichita KS: Kansas University School of Medicine-Wichita, 2005. 16. Gazmararian JA, Curran JW, Parker RM, Bernhardt JM, Debuono BA. Public health literacy in America: an ethical imperative. Am J Prev Med 2005;28:317–22.
American Journal of Preventive Medicine, Volume 29, Number 4