Development of a brief test to measure functional health literacy

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Abstract

We describe the development of an abbreviated version of the Test of Functional Health Literacy in Adults (TOFHLA) to measure patients' ability to read and understand health-related materials. The TOFHLA was reduced from 17 Numeracy items and 3 prose passages to 4 Numeracy items and 2 prose passages (S-TOFHLA). The maximum time for administration was reduced from 22 minutes to 12. In a group of 211 patients given the S-TOFHLA, Cronbach's alpha was 0.68 for the 4 Numeracy items and 0.97 for the 36 items in the 2 prose passages. The correlation (Spearman) between the S-TOFHLA and the Rapid Estimate of Adult Literacy in Medicine (REALM) was 0.80, although there were important disagreements between the two tests. The S-TOFHLA is a practical measure of functional health literacy with good reliability and validity that can be used by health educators to identify individuals who require special assistance to achieve learning goals.

Introduction

In 1993, the National Adult Literacy Survey reported that over 40 million adult Americans were functionally illiterate, meaning they could not perform the basic reading tasks necessary to function fully in society [1]. Another 50 million had marginal reading skills [1]. When these individuals encounter the health care system, they are likely to have significant difficulties with routine reading requirements, such as reading prescription bottles, appointment slips, self-care instructions, and health education brochures 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16. It is important to be able to identify people with limited reading ability so they can receive special instructions regarding medications and chronic disease management (e.g. glucose monitoring for patients with diabetes).

The Test of Functional Health Literacy in Adults (TOFHLA) was designed to measure patients' ability to read and understand the things they commonly encounter in the health care setting using actual materials like pill bottles and appointment slips (i.e. health literacy) [17]. Previous tests of reading ability such as the Rapid Estimate of Adult Literacy in Medicine (REALM) measure only the ability to read and correctly pronounce a list of words. The TOFHLA is a more accurate indicator of a patient's reading ability because it measures comprehension, including the ability to read and understand both prose passages and numerical information. In a study conducted at two public hospitals using the TOFHLA, one third of English-speaking patients were unable to read the most basic health-related materials, and the prevalence of inadequate literacy was markedly higher among the elderly [2].

Other studies have shown that patients with inadequate functional health literacy as measured by the TOFHLA have less knowledge about chronic diseases and self-management, suggesting that current educational strategies are less successful for this group. Despite having an equal number of diabetes education classes, patients with inadequate functional health literacy were less likely to know basic facts about their disease (e.g. range for a normal blood sugar, symptoms of hypoglycemia) or elements of their care plan (e.g. what to do if they developed symptoms of hypoglycemia) [18]. Similarly, patients with hypertension and inadequate functional health literacy were less likely to know basic information about hypertension (e.g. what a normal blood pressure is) and less likely to know what foods had high sodium content [18]. Screening patients with chronic disease prior to educational programs can identify those with inadequate functional health literacy. Providing special assistance to these patients may improve their ability to manage their medical conditions.

Although the original TOFHLA is an effective tool for identifying patients who have inadequate functional health literacy, it takes up to 22 minutes to administer. We therefore developed the short TOFHLA (S-TOFHLA) by reducing the TOFHLA from 17 Numeracy items (e.g. prescription bottles, appointment slips) and 3 prose passages to a version containing 4 Numeracy items and 2 prose passages. The maximum time for administration was reduced from 22 minutes to 12 minutes. This paper describes the development of the S-TOFHLA, its reliability and validity compared to the REALM, and the S-TOFHLA's usefulness for identifying patients with inadequate functional health literacy.

Section snippets

Selection of numeracy items and reading comprehension passages for the S-TOFHLA

The original TOFHLA consists of two sections: a 50-item Reading Comprehension test and a 17-item Numeracy test. The Reading Comprehension test has three health-related passages (Gunning FOG readability 4.3, 10.4, and 19.5, respectively). Each passage has every 5th to 7th word deleted; for each blank, the respondent must select from a list of four words the one that best completes the sentence (modified Cloze procedure) [19]. The Numeracy test assesses quantitative literacy needed in the

Numeracy and reading comprehension scores for the S-TOFHLA

For the testing of the S-TOFHLA, 283 patients were approached. A total of 35 (13%) were not eligible. Of the 248 eligible patients, 30 (12%) refused to participate, and 7 (3%) initiated but failed to complete the survey, leaving 211 (85%) patients who completed the survey. For the patients who completed the survey and the literacy test, the average age was 44 years old, 53% were female, 94% were African American; 42% did not complete high school, 27% completed high school, and 31% had some

Reliability, validity, and practicality of the S-TOFHLA

The S-TOFHLA appears to have good reliability (internal consistency), and it is a valid measure of patients' ability to read the materials they are likely to encounter in the health care setting (i.e. health literacy). Further testing in a larger, more diverse population is needed to confirm this high reliability. The correlation between the S-TOFHLA and the REALM (0.80) was only slightly lower than the correlation between the TOFHLA and the REALM in the original development study (0.84) (17).

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