Karen Crotty

Low health literacy and health outcomes: an updated systematic review.

BACKGROUND Approximately 80 million Americans have limited health literacy, which puts them at greater risk for poorer access to care and poorer health outcomes. PURPOSE To update a 2004 systematic review and determine whether low health literacy is related to poorer use of health care, outcomes, costs, and disparities in health outcomes among persons of all ages. DATA SOURCES English-language articles identified through MEDLINE, CINAHL, PsycINFO, ERIC, and Cochrane Library databases and hand-searching (search dates for articles on health literacy, 2003 to 22 February 2011; for articles on numeracy, 1966 to 22 February 2011). STUDY SELECTION Two reviewers independently selected studies that compared outcomes by differences in directly measured health literacy or numeracy levels. DATA EXTRACTION One reviewer abstracted article information into evidence tables; a second reviewer checked information for accuracy. Two reviewers independently rated study quality by using predefined criteria, and the investigative team jointly graded the overall strength of evidence. DATA SYNTHESIS 96 relevant good- or fair-quality studies in 111 articles were identified: 98 articles on health literacy, 22 on numeracy, and 9 on both. Low health literacy was consistently associated with more hospitalizations; greater use of emergency care; lower receipt of mammography screening and influenza vaccine; poorer ability to demonstrate taking medications appropriately; poorer ability to interpret labels and health messages; and, among elderly persons, poorer overall health status and higher mortality rates. Poor health literacy partially explains racial disparities in some outcomes. Reviewers could not reach firm conclusions about the relationship between numeracy and health outcomes because of few studies or inconsistent results among studies. LIMITATIONS Searches were limited to articles published in English. No Medical Subject Heading terms exist for identifying relevant studies. No evidence concerning oral health literacy (speaking and listening skills) and outcomes was found. CONCLUSION Low health literacy is associated with poorer health outcomes and poorer use of health care services. PRIMARY FUNDING SOURCE Agency for Healthcare Research and Quality.

Interventions for Individuals with Low Health Literacy: A Systematic Review

The U.S. Department of Health and Human Services recently called for action on health literacy. An important first step is defining the current state of the literature about interventions designed to mitigate the effects of low health literacy. We performed an updated systematic review examining the effects of interventions that authors reported were specifically designed to mitigate the effects of low health literacy. We searched MEDLINE®, The Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycINFO, Educational Resources Information Center (ERIC), and the Cochrane Library databases (2003 forward for health literacy; 1966 forward for numeracy). Two reviewers independently reviewed titles, abstracts, and full-text articles for inclusion and included studies that examined outcomes by health literacy level and met other pre-specified criteria. One reviewer abstracted article information into evidence tables; a second checked accuracy. Two reviewers independently rated study quality using predefined criteria. Among 38 included studies, we found multiple discrete design features that improved comprehension in one or a few studies (e.g., presenting essential information by itself or first, presenting information so that the higher number is better, adding icon arrays to numerical information, adding video to verbal narratives). In a few studies, we also found consistent, direct, fair or good-quality evidence that intensive self-management interventions reduced emergency department visits and hospitalizations; and intensive self- and disease-management interventions reduced disease severity. Evidence for the effects of interventions on other outcomes was either limited or mixed. Multiple interventions show promise for mitigating the effects of low health literacy and could be considered for use in clinical practice.