Screening Questions to Predict Limited Health Literacy: A Cross-Sectional Study of Patients With Diabetes Mellitus

Kelly Marvin Jeppesen; James D. Coyle; William F. Miser

doi:10.1370/afm.919

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Figure 1.
Receiver operating characteristic curve of the final model. Area under the curve = 0.9212.

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Table 1.

Distributions of Variables Used to Predict Limited Health Literacy and Results of Bivariate Analyses (N = 225)

Variable	Response Options	Code^a	No. (%)^bof Patients	Crude OR^c	P Value^c
OR=odds ratio; ref=reference group; GED=general equivalency diploma.
^a Represents point values used in the logistic model.
^b Unless otherwise noted.
^c Crude odds ratios and P values are of association with limited health literacy. Exact tests were used for categorical variables; rank-sum test was used for ordinal variables.
^d Odds ratios for some variable values are not reported because the contingency table contained a zero cell.
^e Median (interquartile range).
^f Mean (SD).
^g Age data were normally distributed. P value was determined with a t test.
Highest education level attained	Master’s degree or greater	−4	20 (8.9)	–^d	<.001
	Bachelor’s degree (≥4 years of college)	−3	25 (11.1)	0.18
	Associate’s degree (2 years of college)	−2	22 (9.8)	0.21
	Some college	−1	57 (25.3)	0.25
	12th grade (GED or equivalent)	0	65 (28.9)	(ref)
	11th grade or less	1	32 (14.2)	3.44
	6th grade or less	2	4 (1.8)	13.25
Self-rated reading ability	Excellent or very good	0	112 (49.8)	(ref)	<.001
	Good	1	71 (31.6)	6.66
	Okay	2	35 (15.6)	21.47
	Poor	3	7 (3.1)	–^d
	Terrible or very poor	4	0 (0)	–
Reading enjoyment	1–10	Natural	8 (6–10)^e	–	.01
Single-Item Literacy Screener³⁷	Never	0	140 (62.2)	(ref)	<.001
	Rarely	1	47 (20.9)	3.91
	Sometimes	2	22 (9.8)	4.85
	Often	3	10 (4.4)	24.75
	Always	4	6 (2.7)	–^d
Sex	Male	1	71 (31.6)	2.20	.04
Race	White	–	99 (44.0)	(ref)	–
	Black	–	101 (44.9)	4.83	<.001
	Other	–	25 (11.1)	2.95	.11
Age	Years	Natural	53.76 (12.8)^f	–	.01^g

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Table 2.

Final Logistic Regression Model For Predicting Limited Health Literacy

Variable^a	Adjusted OR^b(95% CI)	Coefficient (SE)	P Value of H₀: Coefficient=0	P Value of H₀: Linear in Logit^c
CI=confidence interval; H₀=null hypothesis; OR=odds ratio; SILS=Single-Item Literacy Screener.
^a Listed in order of introduction into the model during the step-forward process.
^b Odds ratio after adjustment for the other variables in the model.
^c Results of fractional polynomial method.
^d Odds ratios and coefficients reported are per unit increase, according to the code in Table 1.
Self-rated reading ability^d	3.37 (1.71–6.63)	1.22 (0.35)	<.001	.82
SILS result^d	2.03 (1.26–3.26)	0.71 (0.24)	.003	.32
Highest education level^d	1.89 (1.12–3.18)	0.64 (0.27)	.02	.94
Male sex	4.46 (1.53–12.99)	1.50 (0.55)	.006	–
Nonwhite race	3.73 (1.04–13.40)	1.32 (0.65)	.04	–
Constant	–	–4.94 (0.86)	<.001	–

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Table 3.

Performance of the Model in Predicting Limited Health Literacy at Varying Cutoffs of Predicted Probability (N = 225)

Probability Cutoff	Sensitivity, %	Specificity, %	Positive Likelihood Ratio^a	Negative Likelihood Ratio^b
^a The increase in likelihood of having limited health literacy if subject is found to have a positive result (an individual probability equal to or greater than the given cutoff).
^b The decrease in likelihood of having limited health literacy if a subject is found to have a negative result (an individual probability less than the given cutoff).
0.025	100	49	1.95	0
0.05	97	68	3.04	0.04
0.075	88	71	3.06	0.16
0.1	85	77	3.79	0.19
0.2	76	86	5.62	0.27
0.3	68	95	12.92	0.34
0.4	62	96	16.85	0.40
0.5	50	98	23.88	0.51

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Table 4.

SOS Mnemonic for Screening Patients for Limited Health Literacy

	Mnemonic
Question Topic	Letter	Category	Threshold^a
^a Answers that may indicate a problem with health literacy.
^b Single-Item Literacy Screener.³⁷
Educational attainment	S	The person’s Schooling is …	… Sub-Secondary.
Self-rated reading ability	O	The person’s Opinion of his or her reading ability is that …	… he or she is Only an Okay reader.
Help needed when reading^b	S	When the person reads health-related materials, Support is …	… Sometimes Solicited.

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The Article in Brief

Screening Questions to Predict Limited Health Literacy: A Cross-Sectional Study of Patients With Diabetes Mellitus

Kelly Marvin Jeppesen , and colleagues

Background Health literacy, or the ability to obtain and understand health information, is related to one's health and ability to manage medical conditions. Knowing what questions to ask about a patient's learning styles could help clinicians personalize health education for their patients. The purpose of this study is to determine questions and patient characteristics that indicate that a patient may have low health literacy.

What This Study Found Researchers identify 5 screening questions and demographic characteristics that predict whether a patient has limited health literacy: (1) self-rated reading ability, (2) the result of the Single-Item Literacy Screener (a 1-question test that asks, "How often do you need to have someone help you when you read instructions, pamphlets, or other written material from your doctor or pharmacy?"), (3) highest education level attained, (4) sex, and (5) race.

Implications

The authors suggest that clinicians ask questions to identify patients who may need assistance with navigating the health care system or understanding health-related materials.
Asking patients about self-rated reading ability and their highest educational level and the Single-Item Literacy Screener can help in developing strategies to assist patients with low health literacy levels.