Table 1.
Summary of the Characteristics and Critical Appraisal of Included Measures
| Instrument Characteristics | Name of Instrument | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NLS | Spanish NLS | NVS | NLit | NLit-BCa | NLit-S | NLit-P | CNLI | e-NutLiT | SFLQ | NLQ-JP | CHLSalt-HK | IT-FLS | |
| 1. Author (year of publication) | Diamond (2007) | Coffman & La-Rocque (2012) | Weiss et al. (2005) | Gibbs & Harvey (2017) | Gibbs et al. (2016a) | Gibbs, Camargo et al. (2017) | Gibbs, Kennet et al. (2016) | Guttersrud et al. (2014) | Ringland et al. (2016) | Krause, Beer-Borst et al. (2018) | Aihara & Minai (2011) | Chau et al. (2015) | Palumbo et al. (2017) |
| 2. Country of origin | US | US | US | US | US | US | US | Norway | Australia | Switzerland | Japan | Hong Kong | Italy |
| 3. Stated expertise of developers | Not reported | Not reported | A panel of HL experts | Nutrition education research experts | Nutrition education research experts | Nutrition education research experts | Nutrition education research experts | Unclear (manuscripts not in English) | Literacy assessment experts | Not reported | Not reported | Not reported | Not reported |
| 4. Stated purpose and population | To assess NL in adults | To measure NL in Spanish-speaking adults | Brief screening tool to identify limited literacy through assessing ability to read and apply information from a nutrition label among English-speaking primary care patients | To assess NL in nutrition education settings; primary care patients with nutrition-related chronic disease | To assess NL among primary and secondary breast cancer prevention populations | To assess NL in a Spanish-speaking Latino population | To assess parental NL | To assess critical nutrition literacy in nursing students | To assess food label literacy using an electronic assessment tool among Australian adults | To measure self-rated food literacy | To assess NL in Japanese population | To assess health literacy related to salt consumption in older Chinese adults in Hong Kong | To assess individual food literacy skills |
| 5. Method of development: How was the instrument developed (or modified if more applicable) | S-TOFHLA was used as a model. Items were constructed from declara-tive sentences found in nutrition-related websites | The NLS was translated into Spanish. Content validity was assessed through a focus group of Latino adults. One item from the NLS was removed due to lack of meaning following translation, and three additional items were included related to obesity and weight management | Five scenarios developed by a panel ofHL experts. Scenarios and questions were refined after feedback from patients, interviewers, and data analysts about the clarity and ease of scoring of items | Literature review and expert interviews were used to identify five domains of NL for inclusion. A sixth domain was included after pilot-testing a modified item pool with breast cancer patients | The original 40-item NLit that addressed five domains was modified to include concepts from the American Cancer Society's Diet & Cancer Prevention guidelines. A sixth domain was included to assess consumer food shopping skills. To ensure internal consistency, a 75-item draft instrument was initially developed that represented the psychometric properties in breast cancer survivors, and women at high risk for breast cancer | NLit items reviewed by research team to determine relevance of food items for Spanish-speaking Latino community. NLit items were translated through consensus translation by two native Spanish speakers | NLit item pool reduced to 42 items to reflect content and food items relevant for parents of pre-schoolers, as determined by two registered dietitians | Unclear (articles not in English) | Item development and key elements of NL for inclusion in the instrument were informed by data collected through focus groups with dieticians | Three-stage process comprised of: acquisition of background materials; questionnaire development by adapting existing HL questions to be nutrition-specific; and two-stage pre-test | Items were developed to assess participants knowledge of contents of the “Japanese Food Guide Spinning Top” | Based on three domains of HL identified in the literature: functional literacy, factual and procedural knowledge, and awareness. Item development was guided by prior studies on knowledge, attitudes and dietary practices related to salt consumption and nutrition label reading | A concept validation approach was used to design the survey, following the design and development of the European Health Literacy Survey (SØrensen et al., 2013). Three conceptual domains were identified based Vidgen and Gallegos' (2014) definition and model of FL |
| 6. Number of items and domains | 28 items; single domain | 30 items; single domain based on knowledge of nutrition information | Six items based on five scenarios that varied in the type of literacy skills including reading comprehension and numeracy | Long-form (64-item) and short-form (42-item) versions represent six domains of NL: nutrition and health; energy sources in food; household food measurement; food label and numeracy; food groups; and consumer skills | 64-item version of the NLit represented six domains of NL for breast cancer patients | 64-item version of the NLit represented six domains of NL for Spanish-speaking Latino adults | 42 items representing five domains: nutrition and health; household food measurement; food label and numeracy; food groups; and consumer skills | 19 items; two domains: engagement in dietary habits (“engagement”); and taking a critical stance towards nutrition claims and their sources' (“claims”) | 24 items; four domains: identifying nutrition information; calculating/converting serving sizes; comparing products using nutrition information panels; and influence of endorsement logos | 16 items | 10 items based on guidelines that assess recommended dietary habits | 49 items; 8 domains: functional literacy (term recognition and nutrition label reading); knowledge of the salt content of foods; knowledge of the diseases related to high salt intake; knowledge of international standards; myths about salt intake; attitudes toward salt intake; salty food consumption practices; and nutrition label reading practices | 47 items across three domains: plan and manage food literacy (16 items); select and choose FL (15 items); and prepare and consume FL (16 items) |
| 7. How is it administered? | Interview, and pen and paper self-administration | Face-to-face interviews in Spanish | Interview administration | Pen and paper self-administration | Pen and paper self-administration | Pen and paper self-administration | Pen and paper self-administration | Pen and paper self-administration | Electronic tablet format with assistance from administrato | Pen and paper self-administration | Pen and paper self-administration | Pen and paper self-administration | Paper and pencil self-administraton |
| 8. Special requirements for administration | Visual acuity sufficient to read instrument items | Near vision acuity of at least 20/200 on a handheld vision chart. | Visual acuity sufficient to readthe instruments being tested, and have grossly normalcognitive function | Speak and read in English, sufficient visual acuity to read instrument items | Speak and read in English, sufficient visual acuity to read instrument items | Speak and read in Spanish; sufficient visual acuity to read the instrument | Speak and read in English, sufficient visual acuity to read instrument items | Not reported | Visual acuity sufficient to read instrument items; capacity to use electronic tablet | Not reported | Sufficient Japanese reading skills | Speak and understand Cantonese | Speak and read Italian |
| 9. Time it takes to administer | 10 minutes | 10 minutes | 3 minutes | 9 42-item) or 16 (64-item) minutes | Not reported | Not reported | Not reported | <20 minutes | Not reported | Not reported | Not reported | 10–15 minutes | Not reported |
| 10. Scoring | |||||||||||||
| 10a. How is it scored | Single score, 0–28 | 0–30 | Single score 0–6 | Single score for each item | 0–64. Weighted percentages are then calculated giving each domain equal distribution in the total score. | Single score for each item (0–64) | 0–42. Weighted percentages are then calculated giving each domain equal distribution in the total score. | Not reported | 0–12 | Not reported | 0–10 | 0–98 | 0–50 |
| 10b. Scoring categories | Poor (0–7), marginal (8–14), and adequate (15–28) NL | No scoring categories: a higher score indicatesmore NL and a lower score indicatesless NL | >4: adequate literacy when measured by the TOFHLA.A score <4 on the NVS, on the other hand, indicatesthe possibility of limited literacy. Clinicians shouldbe particularly careful in their communication with patients who score <2, as they have >50% chance of having marginal or inadequate literacyskills. | 64 item: likelihood of poor NL (≤44); possibility of poor NL (45–57); likelihood of adequate NL (≥58) (42 item: likelihood of poor NL (≤28); possibility of poor NL (29–38); likelihood of adequate NL (≥39) | Not reported | Likelihood of poor NL (≤44); possibility of poor nutrition literacy. | Not reported | Not reported | Not reported | Not reported | Adequate (score = 10); in adequate (score <10) | Higher score indicates higher health literacy related to salt intake | Inadequate food literacy: 0–25; Problematic food literacy: 25.01–33; Sufficient food literacy: 33.01–42; Excellent food literacy: 42.01–50 |
| Critical appraisal of measures | |||||||||||||
| 1. Is the instrument based on an underlying conceptual framework? | No; the reading comprehension section of S-TOFHLA), was used as a model | No; based on NLS | No; based on scenarios that were developed by a panel ofHL experts based on the concepts and typesof scenarios used in HL research and ingeneral literacy | No; based on literature review and expert panel | No; based on NLit | No; based on NLit | No; based on NLit | Unclear (manuscripts not in English | No; focus groups findings with dieticians and literature | Yes; analyzed definitions of NL and FL and their core components in comparison to established concepts of HL | No; based on Japanese Food and Dietary-related guidelines | No; based on three domains of HL identified by Frisch et al. (2012). | Yes; based on a conceptual model of FL developed by Vidgen and Gallegos (2014) |
| 2. Content validity | |||||||||||||
| 2a. Were intended domains (i.e., relevant areas to be included and excluded) clearly stated? | No | Yes | Candidate scenarios that assess reading comprehension and numeracy | Yes | Yes | Yes | Yes | Yes | Yes | Yes | No | Yes | Yes |
| 2b. Are all relevant components of each domain included? | Partial; the NLS assesses reading comprehension only | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Unclear | No; 12 themes identified; however, included items only covered 10 themes | Unclear | Yes | Yes |
| 3. Face validity | |||||||||||||
| 3a. On the face of it does it describe the intended purpose | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| 3b. Are the definitions of each category clearly specified? | Not applicable | Not applicable | Not applicable | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Not applicable | Yes | Yes |
| 3c. Are these definitions acceptable? | Not applicable | Not applicable | Not applicable | Yes | Yes | Yes | Yes | Yes | Unclear | Yes | Not applicable | Not applicable | Yes |
| 3d. Are the methods for determining the presence and/or absence of criteria described and acceptable? | Yes | Not reported | Yes | Not reported | Not reported | Not reported | Not reported | Not reported | Yes | Not reported | Not reported | Not reported | Not reported |
| 3e. Do the scoring categories sufficiently discriminate considering the stated purpose? | Not reported | Not applicable | Not reported | Yes | Not reported | Yes | Not reported | Not reported | Not reported | Yes | Not reported | Not reported | Yes |
| 4. Construct validity: does the instrument perform in expected ways when compared with other NL/HL/literacy indices? | Partial; correlated with S-TOFHLA (Pearson correlation = .61). Low correlation with self-reported years of education (.41) | Partial; strong relationship with S-TOFHLA (Spearman's rank correlation co-efficient = .65, p < .001), and low correlation with NVS (Spearman's rank correlation coefficient = .16, p = .08) | Partial; moderate correlation with TOFHLA (Pearson correlation r = .59); S-TOFHLA (Pearson correlation coefficient r = .6). Low correlation with REALM (Pearson correlation coefficient r = .41) | Partial; five of six domains had a positive relationship with diet quality (as measured by HEI-2010; p < 0.05): (1) nutrition and health; (2) energy sources in food; (3) food label and numeracy; (4) food groups; (5) consumer skills | Partial; five of six domains had a positive relationship with diet quality (as measured by HEI-2010; p < .05): (1) macronutrients; (2) household food measurement; (3) food label numeracy; (4) food groups; and (5) consumer skills | Partial; five of six domains positively correlated with SAHL-S scores (r = 0.521, p < .001) | Partial; NLit-P scores had positive relationship with child diet quality (r = .418, p < 0.001), parental education (r = .595, p < 0.001), child diet quality (r = .418,p < 0.001), income (r = 0.477, p < .001), and parental age (r = .398, p < 0.001) | No comparisons conducted | Partial; positive relationship between eNutLit and NVS (Spearman's rank correlation coefficient = .73, p < .001). Among obese patients, eNutLit scores associated with education levels (p < .04) and food shopping responsibility (p < .0048) | No comparisons conducted | No comparisons conducted | No; although low correlation was expected between the CHLSalt-HK and the Chinese Health Literacy Scale for Chronic Care (Leung et al., 2013) given the different focus of each measure, the two scales significantly correlated (Pearson correlation coefficient = .29; p < .001) | Partial; positive and significant correlation (p < 0.01, two-tailed) found between NVS and IT-FLS total score (.378), and the three individual scales (.327 to .374) |
| 5. Has sensitivity to change been demonstrated? | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported |
| 6. Reliability | |||||||||||||
| 6a. Has reliability been measured? | Not reported | Not reported | Not reported | Yes; test-retest reliability ranged between 0.51 and 0.80 across six domains; total scale test-retest reliability was adequate (0.88). | Yes; test-retest reliability ranged between fair and substantial across six domains (0.44–0.90). | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Yes; test-retest reliability (n = 41) was adequate (ICC = 0.85; 95% CI [0.707, 0.919]) | Not reported |
| 6b. Inter-rater reliability | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Inconclusive. Comparison of self-administration vs. face-to-face interview (n = 38) was inconclusive due to wide confidence interval (ICC = 0.700; 95% CI [0.457, 0.839]) | Not reported |
| 6c. Intra-rater reliability | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported | Not reported |
| 6d. Internal consistency | Cronbach's alpha = .84 | The Kuder-Richardson coefficientof reliability (KR-20), a variant of the Cronbach'salpha designed for scales with binary items, washigh (KR-20, 5.95), suggesting robust reliability. | Cronbach's alpha = .76 | Entire reliability for the total scale was 0.97 (95% CI, [0.96, 0.98]). Entire reliability was >0.80 for five domains; one domain (consumer skills) approached acceptable reliability (0.75) | Entire reliability was >0.80 for three domains (food label & numeracy; food groups; and consumer skills). The remaining three domains approached acceptable reliability (0.54–0.77) | Entire reliability: total scale: 0.99; across six domains: 0.89–97 Cronbach's alpha: entire instrument: .91; across six domains: .61 to .84 | Entire reliability across five domains ranged from 0.47–0.85 | Engagement scale: Cronbach's alpha = .80; PSI = .77 Claims scale: Cronbach's alpha = .70 (one item deleted); PSI = .71 | Not reported | Not reported | Cronbach's alpha = .86 | Total scale: Cronbach's alpha = .86 Across eight domains: Cronbach's alpha = .39 to .86 | Cronbach's alpha for the total scale (General Food Literacy Index; .91) and the three individual scales (plan and manage FL = .879; select and choose FL = .881; prepare and consume FL = .893) |
| 7. Feasibility | |||||||||||||
| 7a. Is it simple to understand? | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Unclear | Yes | Yes | Yes | Yes |
| 7b. Is it easy to perform and administer? | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| 8. Domains covered in the measure | Knowledge of consumer-related topics in nutrition | Knowledge of consumer-related topics in nutrition | Ability to understand text, and reading and numeracy | Six domains: (1) nutrition and health; (2) energy sources in food; (3) household food measurement; (4) food label and numeracy; (5) food groups; (6) consumer skills | Six domains: (1) nutrition and health; (2) macronutrients; (3)household food measurement; (4) food label and numeracy; (5) food groups; (6) and consumer skills | Six domains: (1) nutrition and health; (2) macronutrients; (3) household food measurement; (4) food label and numeracy; (5) food groups; and (6)consumer skills | Five domains: (1) nutrition and health; (2) household food measurement; (3) food label and numeracy; (4) food groups; and (5)consumer skills | Two domains of CNL: (1)engagement in dietary habits (“engagement”); (2) taking a critical stance towards nutrition claims and their sources' (“claims”) | Four domains: (1)identifying nutrition information; (2) calculating/converting serving sizes; (3)comparing products using nutrition information panels; (4)influence of endorsement logos | Ten themes: across three forms of HL (functional, interactive, and critical) | Ability to obtain basic diet information about recommended dietary habits | Eight domains: (1) functional literacy; (2) knowledge of the salt content of foods; (3) knowledge of the diseases related to high salt intake; (4) knowledge of international standards; (5) myths about salt intake; (6) attitudes toward salt intake; (7) salty food consumption practices; and (8) nutrition label reading practices | Three scales: (1)plan and manage FL; (2) select and choose FL; (3) prepare and consume FL |
| 9. Response options | Cloze procedure with four-option multiple choice format | Cloze procedure with four-option multiple choice format | Correct / incorrect response | Cloze procedure; multiple choice format; categorize items into correct category | Cloze procedure; multiple choice format; categorize items into correct category | Cloze procedure; multiple choice format; categorize items into correct category | Cloze procedure; multiple choice format; categorize items into correct category | 5-point Likert scale | Not reported | Identify the correct response (one item), or 4- or 5-point Likert scale | Binary self-report option: I do know / I do not know | Either a 5-point Likert scale or four multiple-choice options | 4-point Likert scale (very difficult to very easy) |
Note. CHLSalt-HK = Chinese Health Literacy Scale for Low Salt Consumption–Hong Kong; CNLI = Critical Nutrition Literacy Instrument; e-NutLit = Electronic-Nutrition Literacy Tool; FL = food literacy; HEI = Health Eating Index; HL = health literacy; ICC = item characteristic curve; IT-FLS = Italian Food Literacy Survey; NL = nutrition literacy; NLit = Nutrition Literacy Assessment Instrument; NLit-BCa = Nutrition Literacy Assessment Instrument for Breast Cancer; NLit-P = Nutrition Literacy Assessment Instrument-Parents; NLit-S = Nutrition Literacy Assessment Instrument-Spanish; NLQ-JP = Nutrition Literacy Questions for Japanese Population; NLS = Nutrition Literacy Scale; NVS = Newest Vital Sign; PSI = Pearson Separation Index; REALM = Rapid Estimate of Adult Literacy in Medicine; SFLQ = Short Food Literacy Questionnaire; S-TOFHLA = Short Test of Functional Health Literacy in Adults.