CORRESPONDENCE
Measuring Numeracy and Health Literacy in the Emergency Department To the Editor: We read the papers by Carpenter et al.1 and Griffey et al.2 with great interest. With the goal of furthering the understanding of health literacy and numeracy among ED patients, we share additional details regarding our prior work and make available unpublished data (see Data Supplement S1, available as supporting information in the online version of this paper).3 We followed STARD guidelines in our study’s design and execution, although this was not declared explicitly. Health literacy and numeracy levels were computed after the ED visit. The proportion of minority patients reflects the racial distribution of our local geographic area. Education and literacy levels vary by population and geography. Thus, optimal thresholds for identifying limited health literacy may vary according to study goals and prevalence of low health literacy, as positive and negative predictive values fluctuate. There was 4.5% inadequate and 7.5% marginal health literacy in the original validation study by Chew et al.4 We used S-TOFHLA > 22 (adequate health literacy) as the comparison (alloy) standard. Carpenter’s work focused on the test characteristics for identifying limited health literacy (inadequate or marginal health literacy, i.e., S-TOFHLA < 22). To illustrate the effect definition of the reference standard has on interpretation of test characteristics, the area under the curve for the receiver operating characteristics (AUROC) for S-TOFHLA < 23 (i.e., inadequate and marginal health literacy) was 0.26 in our study versus AUROC of 0.74 for S-TOFHLA > 22 (i.e., adequate health literacy). Detailed tables of these analyses including measures of sensitivity and specificity are available online. Similarly, when we compared our measure of subjective numeracy against less than average numeracy measured by the WRAT4, the AUROC was 0.23; the AUROC was 0.77 for identifying adequate numeracy. We also raise awareness of the following issues: 1. The S-TOFHLA and REALM do not directly measure literacy. Although the S-TOHFLA was used as the primary reference standard in the recent works by Carpenter et al. and Griffey et al., we have found the REALM appears to function quite well, requires less time to administer, and appears to measure different aspects of health literacy than the S-TOFHLA. In our work, the correlation between the REALM and S-TOFHLA was 0.56, suggesting that they measure
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ISSN 1069-6563 944 PII ISSN 1069-6563583
different portions of the underlying construct of health literacy. 2. Terminology and abbreviations may add to confusion regarding measures of health literacy and numeracy. Carpenter et al. and Griffey et al. refer to the “single-item literacy test”; it appears that they used the three-item survey developed and validated by Chew et al.,4,5 which we have referred to as the Short Literacy Survey (SLS) and Brief Health Literacy Screen (BHLS).3,6 Morris et al.7 have published work regarding a Single-Item Literacy Screen (also abbreviated SILS), which truly consists of one single question, derived from their three-item survey to screen for low health literacy. Other researchers planning to use these tools may find these distinctions helpful. doi: 10.1111/acem.12426
Candace McNaughton, MD, MPH ([email protected]) Department of Emergency Medicine Vanderbilt University Russell Rothman, MD, MPP Department of Internal Medicine Vanderbilt University Alan Storrow, MD Department of Emergency Medicine Vanderbilt University Ken Wallston, PhD School of Nursing Vanderbilt University Nashville, TN Supervising Editor: Jeffrey Kline, MD.
References 1. Carpenter CR, Kaphingst KA, Goodman MS, Lin MJ, Melson AT, Griffey RT. Feasibility and diagnostic accuracy of brief health literacy and numeracy screening instruments in an urban emergency department. Acad Emerg Med 2014;21:137–46.
© 2014 by the Society for Academic Emergency Medicine doi: 10.1111/acem.12426
ACADEMIC EMERGENCY MEDICINE • August 2014, Vol. 21, No. 8 • www.aemj.org
2. Griffey RT, Melson AT, Lin MJ, Carpenter CR, Goodman MS, Kaphingst KA. Does numeracy correlate with measures of health literacy in the emergency department? Acad Emerg Med 2014;21:147–53. 3. McNaughton C, Wallston KA, Rothman RL, Marcovitz DE, Storrow AB. Short, subjective measures of numeracy and general health literacy in an adult emergency department. Acad Emerg Med 2011;18:1148–55. 4. Chew LD, Griffin JM, Partin MR, et al. Validation of screening questions for limited health literacy in a large VA outpatient population. J Gen Intern Med 2008;23:561–6. 5. Chew LD, Bradley KA, Boyko EJ. Brief questions to identify patients with inadequate health literacy. Fam Med 2004;36:588–94.
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6. Wallston KA, Cawthon C, McNaughton CD, Rothman RL, Osborn CY, Kripalani S. Psychometric properties of the brief health literacy screen in clinical practice. J Gen Intern Med 2014;29:119–26. 7. Morris NS, MacLean CD, Chew LD, Littenberg B. The Single Item Literacy Screener: evaluation of a brief instrument to identify limited reading ability. BMC Fam Pract 2006;7:21. Supporting Information The following supporting information is available in the online version of this paper: Data Supplement S1. Detailed report of sensitivity and specificity: patient reported health literacy vs. adequate literacy by S-TOFHLA.
Measuring Numeracy and Health Literacy in the Emergency Department To the Editor: We read the papers by Carpenter et al.1 and Griffey et al.2 with great interest. With the goal of furthering the understanding of health literacy and numeracy among ED patients, we share additional details regarding our prior work and make available unpublished data (see Data Supplement S1, available as supporting information in the online version of this paper).3 We followed STARD guidelines in our study’s design and execution, although this was not declared explicitly. Health literacy and numeracy levels were computed after the ED visit. The proportion of minority patients reflects the racial distribution of our local geographic area. Education and literacy levels vary by population and geography. Thus, optimal thresholds for identifying limited health literacy may vary according to study goals and prevalence of low health literacy, as positive and negative predictive values fluctuate. There was 4.5% inadequate and 7.5% marginal health literacy in the original validation study by Chew et al.4 We used S-TOFHLA > 22 (adequate health literacy) as the comparison (alloy) standard. Carpenter’s work focused on the test characteristics for identifying limited health literacy (inadequate or marginal health literacy, i.e., S-TOFHLA < 22). To illustrate the effect definition of the reference standard has on interpretation of test characteristics, the area under the curve for the receiver operating characteristics (AUROC) for S-TOFHLA < 23 (i.e., inadequate and marginal health literacy) was 0.26 in our study versus AUROC of 0.74 for S-TOFHLA > 22 (i.e., adequate health literacy). Detailed tables of these analyses including measures of sensitivity and specificity are available online. Similarly, when we compared our measure of subjective numeracy against less than average numeracy measured by the WRAT4, the AUROC was 0.23; the AUROC was 0.77 for identifying adequate numeracy. We also raise awareness of the following issues: 1. The S-TOFHLA and REALM do not directly measure literacy. Although the S-TOHFLA was used as the primary reference standard in the recent works by Carpenter et al. and Griffey et al., we have found the REALM appears to function quite well, requires less time to administer, and appears to measure different aspects of health literacy than the S-TOFHLA. In our work, the correlation between the REALM and S-TOFHLA was 0.56, suggesting that they measure
944 944
ISSN 1069-6563 944 PII ISSN 1069-6563583
different portions of the underlying construct of health literacy. 2. Terminology and abbreviations may add to confusion regarding measures of health literacy and numeracy. Carpenter et al. and Griffey et al. refer to the “single-item literacy test”; it appears that they used the three-item survey developed and validated by Chew et al.,4,5 which we have referred to as the Short Literacy Survey (SLS) and Brief Health Literacy Screen (BHLS).3,6 Morris et al.7 have published work regarding a Single-Item Literacy Screen (also abbreviated SILS), which truly consists of one single question, derived from their three-item survey to screen for low health literacy. Other researchers planning to use these tools may find these distinctions helpful. doi: 10.1111/acem.12426
Candace McNaughton, MD, MPH ([email protected]) Department of Emergency Medicine Vanderbilt University Russell Rothman, MD, MPP Department of Internal Medicine Vanderbilt University Alan Storrow, MD Department of Emergency Medicine Vanderbilt University Ken Wallston, PhD School of Nursing Vanderbilt University Nashville, TN Supervising Editor: Jeffrey Kline, MD.
References 1. Carpenter CR, Kaphingst KA, Goodman MS, Lin MJ, Melson AT, Griffey RT. Feasibility and diagnostic accuracy of brief health literacy and numeracy screening instruments in an urban emergency department. Acad Emerg Med 2014;21:137–46.
© 2014 by the Society for Academic Emergency Medicine doi: 10.1111/acem.12426
ACADEMIC EMERGENCY MEDICINE • August 2014, Vol. 21, No. 8 • www.aemj.org
2. Griffey RT, Melson AT, Lin MJ, Carpenter CR, Goodman MS, Kaphingst KA. Does numeracy correlate with measures of health literacy in the emergency department? Acad Emerg Med 2014;21:147–53. 3. McNaughton C, Wallston KA, Rothman RL, Marcovitz DE, Storrow AB. Short, subjective measures of numeracy and general health literacy in an adult emergency department. Acad Emerg Med 2011;18:1148–55. 4. Chew LD, Griffin JM, Partin MR, et al. Validation of screening questions for limited health literacy in a large VA outpatient population. J Gen Intern Med 2008;23:561–6. 5. Chew LD, Bradley KA, Boyko EJ. Brief questions to identify patients with inadequate health literacy. Fam Med 2004;36:588–94.
945
6. Wallston KA, Cawthon C, McNaughton CD, Rothman RL, Osborn CY, Kripalani S. Psychometric properties of the brief health literacy screen in clinical practice. J Gen Intern Med 2014;29:119–26. 7. Morris NS, MacLean CD, Chew LD, Littenberg B. The Single Item Literacy Screener: evaluation of a brief instrument to identify limited reading ability. BMC Fam Pract 2006;7:21. Supporting Information The following supporting information is available in the online version of this paper: Data Supplement S1. Detailed report of sensitivity and specificity: patient reported health literacy vs. adequate literacy by S-TOFHLA.
