Understanding the Impact of Health Literacy
on Informed Consent
A common theme running
through many of the barriers just introduced is the low
rate of health literacy seen in the American population.
Health literacy has been defined as the ability to read,
understand, and act upon health information. [AMA1999] Broadening
this definition beyond the individual patient, the Institute
of Medicine has recently called health literacy: “...the
degree to which individuals can obtain, process, and understand
the basic health information and services they need to make
appropriate health decisions. But health literacy goes beyond
the individual. It also depends upon the skills, preferences,
and expectations of health information and care providers:
our doctors; nurses; administrators; home health workers;
the media; and many others.” [IOM 2004]
However defined, health literacy is in short supply. The
2003 National Assessment of Adult Literacy found that about
36% of adults had Basic or Below Basic health literacy (versus
Intermediate or Proficient levels) and that these individuals
were more likely to get their information about health issues
from radio and television instead of newspapers, magazines,
books, or the internet. [NCES 2007] These findings seemed
to confirm earlier estimates that over 90 million Americans
lack basic health literacy skills [Kirsch 2002] and that
47 million Americans, or almost half of the adult population
of this country,were either functionally illiterate, or
marginally literate. [Kirsch 1993]. It should be noted that
those with limited English proficiency were excluded from
the NAAL survey and so language barriers cannot explain
the findings. Another recent analysis of 85 carefully screened
medical research papers found that the prevalence of low
health literacy was 26% (95% confidence interval 22% to
29%) and the prevalence of marginal literacy was 20% (95%
confidence interval 16% to 23%). [Paasche-Orlow 2005] Even
accounting for the bias in these publications for populations
with low socioeconomic status, these results imply that
nearly half of the population in the reviewed studies had
health literacy skills that would impede their understanding
of most informed consent forms.
In fact, beyond health literacy, surveys have shown that
many Americans have significant deficits in fundamental
reading, writing, and numeracy skills, which interferes
substantially with their ability to function normally in
society. In the 2003 National Assessment of Adult Literacy,
for example, 22% of adults were at the lowest possible level
of quantitative literacy (Below Basic), indicating that
they possessed no more than the most simple and concrete
literacy skills. [NCES 2007a] Based on this same report,
it is estimated that some 30 million American adults have
Below Basic prose literacy, 27 million have Below Basic
document literacy, and 46 million have Below Basic quantitative
literacy. [NCES 2007b]
The scope of this problem is broad and reaches across ethnic,
racial, and economic lines. In sheer numbers, most of those
with low literacy skills in the United States are white,
native-born Americans. However, specific demographic groups
are at higher risk for low literacy. These include: ethnic
minorities, the elderly, unemployed persons, and those with
a lower level of education or limited income. [Kirsch 1993,
Paaschle-Orlow 2005]
Individuals with low or limited literacy skills have poorer
health outcomes. They are less likely to seek preventive
care or to comply with prescribed treatment. In one recent
study, for example, poor literacy was linked to poor HIV
medication adherence among African American patients and
was cited as a possible cause of HIV health disparities.
[Osborn 2007] Another recent study found that limited health
literacy was a barrier to patients taking medications for
hypertension. [Persell 2007] In addition, patients with
low literacy are at higher risk for hospitalization and
tend to stay in the hospital longer. Their need for additional
care results in annual health care costs four times higher
than those with higher literacy skills. [Doak 1996; Weiss
1999; Baker 1996] People with low or limited literacy face
significant risks when attempting to navigate the healthcare
system [MEPS 2008] and when making truly informed decisions
about their care. Identifying individuals with low health
literacy skills may not always be possible, but assuring
that every individual understands an informed consent is
critical to providing the best possible care—care
that is not just medically sound, but also ethically and
legally sound.
Developed with a grant from the Robert Wood Johnson Foundation
