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Make the Diagnosis: Health Literacy

Prior Probability of Inadequate or Marginal Health Literacy

In populations of lower socioeconomic status and education, 26% of patients have inadequate literacy and 20% have marginal literacy.1 Among seniors enrolled in US Medicare plans, 34% of English-speaking and 53% of Spanish-speaking enrollees had inadequate or marginal literacy.2

Population for Whom Inadequate or Marginal Health Literacy Should Be Considered

The decision to screen routinely for health literacy is controversial because the prevalence is high enough that routinely ensuring patients’ understanding by having them “teach back” instructions seems prudent. However, this does not ensure that patients will be able to read and understand important information in the absence of someone to help. While education level is associated with literacy, the obtained education level is not a valid proxy for health literacy. Factors shown to be associated with literacy problems include older age, lower knowledge of disease, lower utilization of preventive services, hospitalization, poor overall health status, poor control of chronic disease, and higher predicted mortality rates.

Assessing the Likelihood of Inadequate or Marginal Health Literacy

Single-item questions are more pragmatic than multi-item questionnaires. Patients who acknowledge trouble reading forms and written hospital materials can be assumed to have inadequate literacy, but denial of difficulty does not rule out impaired literacy (likelihood ratio (LR), 0.81; 95% confidence interval (CI), 0.78-0.84).3 Thus, indirect single questions are best employed (see Table 79-1).

Table 79-1Likelihood Ratios That a Patient Has Inadequate or Marginal Health Literacy

Reference Standard Tests

The Test of Functional Health Literacy in Adults (TOFHLA) is the accepted reference standard. The test may require over 20 minutes to complete. The test assesses literacy for both written information and numeracy.4


1. +
Paasche-Orlow  MK, Parker  RM, Gazmararian  JA, Nielsen-Bohlman  LT, Rudd  RR. The prevalence of limited health literacy. J Gen Intern Med. 2005;20(2):175–184.
[PubMed: 15836552]
2. +
Gazmararian  JA, Baker  DW, Williams  MV  et al.. Health literacy among Medicare enrollees in a managed care organization. JAMA[JAMA and JAMA Network Journals Full Text]. 1999;281(6):545–551.
[PubMed: 10022111]
3. +
Williams  MV, Parker  RM, Baker  DW  et al.. Inadequate functional ...

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