The Evaluation and Measurement of Health Literacy

This is a guest blog post by Dr. Heather F. de Vries McClintock PhD MSPH MSW, IH Section Member and Assistant Professor in the Department of Public Health, College of Health Sciences at Arcadia University. It is the third blog in a three-part series the IH Blog will feature this summer, Global health literacy: Conceptual basis, measurement and implications.

Part III. The Evaluation and Measurement of Health Literacy

While the IOM’s (now National Academy of Medicine) definition of health literacy (HL) is recognized and accepted, there is a lack of standardization in its conceptualization and operationalization within and between countries. Initially HL was perceived as a derivation of literacy with it’s primary purpose serving to as important tools to maximize comprehension during clinical encounters. In recent years the meaning and purpose of HL have broadened in scope to incorporate a health promotion perspective. This expanded and dynamic definition has resulted in increased utility in both clinical medicine and public health but has left this construct susceptible to conceptual drift.  A recent systematic review of the construct of HL found 17 varying definitions and 12 conceptual models that were employed in the literature.  

According to IOM’s report Health Literacy: Improving Health, Health Systems, and Health Policy Around the World: Workshop Summary, countries around the world have used a wide range of designs and approaches as well as purposes for examining HL.  These approaches have involved the usage of proxies such as education, income, or literacy to approximate HL. Other countries have relied on single items, often as a part of other measures (e.g. school attendance/enrollment, reading score), to evaluate HL. Thus, currently there is lack of comparability between estimates of HL within and between countries. Furthermore, the validity of many measures in assessing IOM’s definition of HL remains unclear. It is important to note that nearly all of the studies in this review were conducted in high income countries. Very little research has constructed a measure for use in LICs and LMICs. A robust measure of HL provides the foundation for comparison of HL across countries as well as its evaluation in relation to health outcomes.

My colleagues and I (see acknowledgements below) sought to develop a robust measure of HL using data from Demographic Health Surveys (DHS) conducted between 2006-2015 in 14 developing countries: Cameroon, Democratic Republic of the Congo, Ethiopia, Ghana, Guinea, Ivory Coast, Lesotho, Rwanda, Niger, Namibia, Sierra Leone, Swaziland, Toto, and Zambia. The same survey was administered in all countries, after translation into versions appropriate by language.  The DHS Program is administered by the United States Agency for International Development (USAID). Beginning in 1984, surveys have been administered in over 90 countries. The DHS survey includes items that represent domains of the IOM definition of HL. We identified eight survey questions that corresponded to elements of the four domains of health literacy as defined by the IOM: capacity to interpret, capacity to obtain, capacity to understand, and ability to make appropriate health decisions. We then applied factor analysis methods to extract a single factor – a measure of health literacy – and evaluate the results for reliability and validity.

In our work, a total of 259,684 individuals between the ages of 15 and 49 years were included.  The derived dichotomous measure of health literacy demonstrated internal consistency (Cronbach’s α = 0.72), good content validity, and importantly, was comprised of the elements described by the IOM.  The prevalence of high health literacy overall was 35.2%.  Health literacy varied by sex (females, 34.1% vs males, 39.2%) and education level (primary education or less, 8.9%, some secondary education, 69.4%, secondary education or higher, 84.4%). Health literacy varied considerably across nations, from 8.5% in Niger to 63.9% in Namibia.  

This was the first study to derive a robust indicator of health literacy following the IOM definition in a large number of national samples. In future work we plan to use this indicator with DHS datasets to measure health literacy in other countries, and ultimately test how health literacy relates to health behavior and outcomes, including for HIV/AIDS and domestic violence. An abstract of these findings was published in the Lancet Global Health, Volume 5, Special Issue, S18, April 2017.

Acknowledgements:

The following individuals contributed to the investigation of HL as discussed in this blog series:

Douglas J. Wiebe, Phd, Associate Professor, Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania

Julia M. Alber, Phd, Postdoctoral Fellow, Center for Health Behavior Research, University of Pennsylvania

Sara M. Schrauben, MD, Renal Research Epidemiology Fellow, University of Pennsylvania

Carmella M. Mazzola, College of Health Sciences, Arcadia University

Ashley Andrews, MPH, Perelman School of Medicine, University of Pennsylvania

McClintock.Picture

Dr. Heather F. de Vries McClintockis currently Assistant Professor of Public Health at the College of Health Sciences at Arcadia University. Her research broadly focuses on the prevention, treatment, and management of chronic disease and disability globally. Recent research aims to understand and improve health literacy and the quality of care provision for persons in Sub-Saharan Africa.

 

 

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