Table 1.

The general characteristics of the articles.

Study, Year (Reference)	Design	Instrument	Quality score	Study sample	Outcomes	Analysis	Variables Used in Multivariate Analysis
Aboumatar et al., 2013 [23]	Cross-sectional	REALM	Fair	275 patients from 14 USA primary care sites Mean age, 61 yr Female, 65.8% White, 36.7%	BP control Medical decision making Patient-physician communication Patient's trust in their physician	Fisher's exact tests Jonckheere-Terpstra tests Two sample t-tests Generalized linear models regression analysis	Age, gender, race, education, annual income; blood pressure controlled; insurance pays prescriptions; age of physician seen, seen by female physician, seen by white physician
Ahn et al., 2016 [33]	Cross-sectional	REALM	Fair	289 hypertensive patients from south Korea Mean age, 68.92 yr Female, 77.2%	Medication adherence	Descriptive statics Hierarchical regression	Age, gender, marital status, place of residence; self-efficacy, comorbidities
Bosworth et al., 2008 [26]	Cross-sectional	REALM	Fair	608 patients from 2 Duke University Health System Primary care clinics Mean age, 61yr Female, 365 Inadequate income, 18% Less than 12th grade, 36%	BP control	Logistic regression Multivariable model	Age, gender, recall; medication barriers score, medication non-adherent, low hypertension knowledge, often feel stressed, participatory decision-making, hypertension worry score, lack personal control of health, have emotion support, have home BP monitor, >5yr since high BP diagnosis, number of medication side effects, no weekly exercise, diabetes, current smoker, family history of hypertension
Gazmararian et al., 2003 [29]	Cross-sectional	S-TOFHLA	Fair	653 patients from Cleveland; Houston; South Florida, including Ft. Lauderdaleand Miami; and Tampa, USA Mean age, 72 yr Female, 61.7% Black, 16.1% Less than 12th grade, 67.1% Inadequate literacy, 24%	Chronic disease knowledge	Description statistic Multiple linear regression analysis	Age, disease duration, attended a class
Hall et al., 2016 [25]	Cross-sectional	SAHLSA	Good	45 Latino Migrant Seasonal Farm workers at Georgia and Ellenton Clinic, USA	BP control Medication adherence BP knowledge BP self-care	Descriptive statistic Hierarchical regression Mann-Whitney U test Logistic regression	Education, blood pressure knowledge, perceived stress, acculturation level
Ingram et al., 2013 [32]	Cross-sectional	REALM	Fair	121 African American participants at USA Forsyth county Mean age, 59 yr Female, 50% Less than 12th grade, 70%	Adherence to antihypertensive regiments	Spearman Rho correlations Multiple regression analysis	Age, education level, annual income; understanding of health/prescription information, health status, access to health care, comorbidities
Ko et al. 2013 [28]	Cross-sectional	STOFHLA Singapore	Fair	306 patients at the Singapore Government-funded primary care clinic Mean age, 58 yr Female, 36.3% Chinese, 69.0% Duration of hypertension, 8yr	Hypertension knowledge BP control	Independent t-test Chi-squared test Multiple linear regression analysis	Age, gender, ethnicity, education, housing type; comorbidities,
Lenahan et al., 2013 [34]	Cross-sectional	S-TOFHLA	Fair	215 participants from six USA primary care safety net clinics Mean age, 60 yr Female, 68.2% African American, 80.4% Limited literacy, 47.0%	Medication non-adherence BP control Emergency department and Hospitalization visits	One-way analysis of variance Chi-square analyses Generalized linear models Robust error estimation	Age, gender, race; number of antihypertensive medications taken, number of chronic conditions, medication identification
Mcnaughton et al., 2014 [24]	Cross-sectional	REALM	Fair	423 participants an inner city primary care clinic in Atlanta, Georgia, USA Mean age, 64 yr Female, 56% African American, 91% Mean education, 12 yr	BP control Medication adherence	Descriptive statistics Logistic regression Planned exploratory linear regression	Age, gender, race, education, employment status
Osborn et al., 2011 [30]	Cross-sectional	S-TOFHLA	Fair	330 patients from 6 primary USA care safety net clinics in Grand Rapids, Michigan; Chicago, Illinois; and Shreveport, Louisiana Mean age, 53 yr Female, 67.9% African American, 78.5% Less than 12th grade, 39.3% Married, 30.6%	Hypertension knowledge Self-efficacy Self-care behaviors Health status	Independent samples t-test Chi-square tests Two path analytic models	Age, race, education; knowledge, self-efficacy, self-care
Pandit et al., 2009 [4]	Cross-sectional	S-TOFHLA	Fair	330 patients from 6 primary USA care safety net clinics in Grand Rapids, Michigan; Chicago, Illinois; and Shreveport, Louisiana. Mean age, 53 yr Female, 67.9% African American, 78.5% Less than 12th grade, 39.3% Married, 30.6%	Hypertension knowledge BP control	Chi-square Student's t-tests Multivariate logistic regression Mediation analysis	Age, gender, race, marital status, employment status, insurance coverage; number of comorbid conditions, years treated for hypertension, clinic site, education level
Perez, 2015 [36]	Cross-sectional	NVS	Good	144 patients from various USA churches in the St. Louis, Missouri, and metro east Illinois area and Hispanic Community Mean age, 47 yr Female, 52.1% Less than 8 yr education, 30% Foreign-born Hispanics, 92.4%	Illness perception	Hierarchical multiple regression Analysis of variance t-tests	Age, gender, years of education, acculturation
Persell et al., 2007 [19]	Cross-sectional	S-TOFHLA	Fair	119 patients from three USA primary care clinics in Grand Rapids, Michigan affiliated with a federally qualified health center Mean age, 55 yr Female, 69.5% Black, 60.5% Less than 12th grade, 32.77%	Blood pressure The number of medications for high blood pressure The number of medications patients can name them	Chi-square tests Fisher's exact test Student's t-test Multivariable logistic regression	Age, household income
Shi et al., 2017 [27]	Cross-sectional	Chinese health literacy scale for hypertension	Fair	360 patients from Jinyang community health center in Chengdu, China. Mean age, 66.6 yr Female, 55.8%	Blood pressure control Health quality Risk for ischemic cerebral vascular disease Brachial-ankle artery pulse wave velocity	Independent t tests Mann–Whitney U test Wilcoxon test Chi-square test Multiple logistic regression analysis	Age, gender, education level, work status, monthly income; course of hypertension
Rao et al., 2015 [31]	Cross-sectional	REALM Three-item numeracy scale	Fair	409 participants from 12 primary care clinics in central North Carolina, USA Mean age, 47.9 yr Female, 56%	The completeness of home blood pressure monitoring	Student's t-test Logistic regression	None
Wang et al., 2017 [35]	Cross-sectional	BHLS	Fair	882 patients from six China towns Mean age, 65.87 yr Female, 56.1%	Health quality	Frequencies, percentages Mann–Whitney U test Kruskal–Wallis test Structural equation modeling	Age, gender, education, family yearly income, family yearly medical costs,
Wannasirikul et al., 2016 [21]	Cross-sectional	Functional, communicative, critical health literacy scale		600 patients from a Primary Health Care Center in Sa Kaeo Province, Thailand Mean age, 65.3 yr Female, 75.8%	Blood pressure Medication adherence	Descriptive statistics Path analysis	Age, gender, marital status, income per month, education level, occupation; perception on vision, perception on hearing, perception on mental health, duration of diagnosed HT, social support
Willens et al., 2013 [22]	Cross-sectional	BHLS	Good	23483 patients from three USA primary care clinics Mean age, 65 yr Female, 58.3% Black, 23.1% Less than high school, 15.2%	Blood pressure BP control	Bivariate analysis Wilcoxon rank-sum test Pearson's chi-square	Age, gender, race, education years, location
Williams et al. 1998 [20]	Cross-sectional	TOFHLA	Fair	504 patients from 2 USA urban public hospitals Mean age, 59 yr Female, 87.5% Black, 59.52% Less than 12th grade, 83.9%	Knowledge of disease	Chi-square tests One-way analysis of variance Multiple linear regression Multivariate logistic regression	Age, sex, race, years of schooling, native language

Note: REALM = the Rapid Estimate of Adult Literacy in Medicine; TOFHLA = the Test of Functional Health Literacy in Adults; SAHLSA = the Short Assessment of Health Literacy for Spanish-speaking Adults; S-TOFHLA = the Short Version of the Test of Functional Health Literacy in Adults; NVS = the Newest Vital Sign; BHLS = the Brief of Health Literacy Screen.