China is a large country with a population of about 1.339 billion, 50.3% of whom reside in rural areas [1] and has the largest hypertensive population in the World [2,3]. From 1991 to 2002, hypertension prevalence increased from 16.3% to 21.0% among urban adults, and from 11.1% to 18.0% among rural adults [2,4,5]. The increase in prevalence in rural areas is due to economic development, resulting in the adoption of urban lifestyles, as well as improved case-finding [6,7].

Hypertension-related diseases cost 31.89 billion Yuan Renminbi (RMB, approximately 4.8 billion dollars US) per year and result in about 11.4 years of life lost [8,9]. Chronic disease prevention has been identified as a high public health need in China’s 2009 health reforms, with national and local governments allocating 15 Yuan (approximately 2.2 dollars US) per person per year for basic public health services, including chronic disease prevention, with high priority placed on hypertension prevention and management [10]. In rural areas, primary care physicians are required to measure blood pressure, register and follow-up with patients, and provide hypertension education [11,12].

Rural areas in northeast China have the highest rates of hypertension and stroke in the country [6,7]. To eliminate the geographic disparity, efficient hypertension prevention, control, and management programs must be developed in these areas under the Chinese public health initiative. Health literacy is related to hypertension management, treatment and outcomes [13,14]. Andeseun et al. [14] surveyed 72 patients in newly initiated dialysis and found that the average reading of diastolic blood pressure was lower among patients with adequate health literacy skills than those without the skills. Thus, we conducted this study to evaluate the level of current hypertension knowledge, factors associated with hypertension knowledge, and the association between hypertension knowledge and the frequency of salty food consumption among hypertensive and non-hypertensive populations in rural areas of Heilongjiang province, China. Our findings are essential to identify the gaps in current hypertension knowledge, and thus to inform the development of effective health education programs for the prevention and management of hypertension.

Of the 1,519 individuals who participated in the survey, 665 were hypertensive and 854 were non-hypertensive respondents (see Table 1). In both groups, a majority of the respondents were 50 to 64 years old, were married, and had a low level of education. Chronic disease was more frequent among hypertensive than among non-hypertensive respondents (71.6%vs. 54.8%). Quality of life scores were worse for hypertensives than non-hypertensive respondents.

The percentage of respondents with correct responses to the hypertension knowledge questions ranged from 18.0% to 71.9% among hypertensive respondents and 11.8% to 63.0% among non-hypertensive respondents (see Table 2). Of the respondents, 83.0% of hypertensive and 89.8% of non-hypertensive respondents had a score of fewer than 50 points out of a possible 100. Furthermore, 12.0% of hypertensive and 25.1% of non-hypertensive respondents had scores of 0, that is incorrect answers to all 10 questions (see Figure 1).

The average hypertension knowledge score was 25.6 out of the maximum 100 points for hypertensive and 20.0 for non-hypertensive respondents (see Table 3). Only a small proportion of respondents correctly answered questions about hypertension complications (i.e., 36.5% for stroke, 38.9% for heart attack, 18.0% for kidney disease and 27.9% for eye disease among hypertensive respondents and 31.2% for stroke, 32.1% for heart attack, 11.8% for kidney disease and 19.6% for eye disease among non-hypertensive respondents). The average score varied by age, education and marital status.

The factors associated with hypertension knowledge for both groups included marital status, education, when blood pressure had been measured, receiving hypertension education, and reading books, newspapers and magazines (see Table 4). In addition to these factors, mental health status was related to hypertension knowledge in non-hypertensive respondents (lower level for respondents with poor mental health) and the presence of a chronic disease was related to higher hypertension knowledge in hypertensive respondents. The major source of hypertension knowledge was health practitioners (62.4% for hypertensive and 32.2% for non-hypertensive respondents) and media (33.4% for hypertensive and 37.2% for non-hypertensive respondents).

The frequency of eating salty pickled vegetables in the last week was lower among those who answered the question “eating less salt usually makes blood pressure go down” correctly than those who answered the question incorrectly (66.1% versus 70.1%, risk adjusted odds ratio: 0.834 and 95% confidence interval (95% CI): 0.578–1.202 among hypertensive respondents and 70.6% versus 77.2%, odds ratio: 0.710 and 95% CI: 0.514–0.979 among non-hypertensive respondents, see Table 5).

Among hypertensive respondents, 48.3% had a systolic/diastolic blood pressure ≥140/90. The proportion slightly decreased with higher hypertension knowledge. However, the differences were not statistically significant after adjustment for covariates (see Table 6).

This survey clearly demonstrates that hypertension knowledge levels are extremely low in rural areas of northeast China. Although the level is statistically different between hypertensive and non-hypertensive respondents (mean score of 26 versus 20 out of a potential score of 100, p < 0.05), the difference is small. Many people lacked knowledge about hypertension complications and medication. Among non-hypertensive respondents, knowledge level was related to dietary behavior: people who knew about the relation between salty food and blood pressure ate salty food less frequently than those who did not know the relation.

Hypertension knowledge is extremely low, regardless of hypertension status, in our sample. Astonishingly, 12% of hypertensive and 25% of non-hypertensive respondents had a score of 0, incorrect answers to all 10 questions. The hypertension knowledge level in China rural areas we reported is much lower than previous reports from western countries [20,21,22,23,24,25,26,27]. For example, Sanne et al. [16] surveyed 296 hypertensive adults in the New Orleans metropolitan area using the same 10-item questionnaire as we used, and reported that 50% of the respondents answered at least seven questions correctly, and the correct response rate ranged from 41.9% to 98.0%, much higher than the 11.8%–63.0% range in our hypertensive respondents. Ayotta et al. [25] assessed hypertension knowledge using six questions among 1177 hypertensive patients in the United States. The study found correct response rates ranged from 43.9% to 93.1% across the six items, with 92.2% correctly answering the question of hypertension causing kidney problems, much higher than our finding of 18.0% on that item.

Our study demonstrated that hypertension knowledge levels were associated with marital status, education, health status, periodically reading books, newspapers or other materials, history of blood pressure measurement, and attending hypertension educational sessions provided by clinicians. However, the knowledge levels did not vary by age or sex. In our sample, 77.3% of hypertensive and 62.3% of non-hypertensive respondents were illiterate or had elementary schooling. Those who were illiterate had poorer hypertension knowledge than those with elementary or higher levels of schooling. This is congruent with our additional finding that people with regular reading habits had higher hypertension knowledge levels. These findings indicate that hypertension education programs should pay attention to adults with low literacy levels.

In fact, 62.4% of hypertensive and 32.2% of non-hypertensive respondents acknowledged that they received knowledge from their health practitioners. In the villages we studied, physicians or nurses regularly provide health education to residents, including hypertension education. We found that respondents who participated in the educational sessions had better hypertension knowledge than those who did not. In addition, hypertensive respondents with chronic diseases are likely to have better knowledge than those without, suggesting that healthcare providers take the opportunity to provide hypertension education when they have contact with their patients. Residents in rural areas generally do not go for regular health examinations unless they have a health problem, and thus have few opportunities to learn about hypertension.

Our study evidenced that current educational programs have positive effects. Respondents reported that village health practitioners are the major source of hypertension information and respondents who attended educational sessions had better knowledge than those who did not attend. Therefore, hypertension educational sessions should be continuously provided by village health practitioners, such as physicians and nurses, and should further target the marginal populations such as individuals who are not married, are illiterate or have poor mental health status. Since health practitioners live in the village, they are familiar with each individual’s social and cultural characteristics and health status and are therefore in a position to identify these target groups. In addition, village residents are likely to trust them, and therefore attend and follow the instructions provided in the educational sessions.

Non-hypertensive respondents who understood that salt was a risk factor for hypertension ate salty food less frequently than those who did not know that, illustrating that hypertension knowledge has an impact on preventive health behavior as reported by William et al. [20] There is an opportunity for educational programs to emphasize the long-term consequences of hypertension and to influence behavior. In this study, a majority of respondents were unaware of possible hypertension complications. For example, only 18% of the hypertensive and 11.8% of the non-hypertensive respondents knew hypertension could cause kidney disease. Only 49% of the hypertensive respondents knew that they needed to take medication daily. A lack of understanding of the long term health outcomes of hypertension may lead to poor compliance with antihypertensive medication; sufficient evidence indicates that patients have better drug-adherence if they are aware that an increased blood pressure could reduce their life expectancy [12,28]. Our study demonstrated that the proportion of hypertensive respondents who met blood pressure control targets (≥140/90) was slightly increased with higher levels of hypertension knowledge.

The survey found that respondents obtained hypertension knowledge mainly from the village clinics. Therefore, it is imperative to enhance roles of rural physicians in health literacy promotion. First, health professionals including nurses should be incentivized to lead inhealth promotion and education activities. Second, the Chinese government has invested resources for chronic disease management and control. A certain amount of these resources should be specifically allocated to hypertension. Third, blood pressure monitors should be installed at pharmacies and clinics for free measurement. Fourth, education program should target high risk populations and sodium reduction. The essential information about hypertension should be disseminated through radio, mobile phone text massage, and posters at the village clinics.

This study has limitations. First, we interviewed people who came to interview sites and were unable to assess an exact response rate. If this convenience sample had better health knowledge than those who were not surveyed, our findings about current hypertension knowledge levels could be over-estimated. Second, we missed people who were temporarily away from these villages for various reasons, such as working in urban areas. These people were deemed to be relatively healthy. Third, we surveyed two counties in the Heilongjiang Province of China; generalizing our findings to other regions should be done with caution. Fourth, we assessed salt consumption using frequency of eating salty pickled vegetable as a proxy. This method does not accurately quantify total salt consumption. Nevertheless, our study is consistent with previous studies in China [29,30], which reported low hypertension knowledge in rural areas.

Our study also has several strengths. The interview was conducted by medical students who are knowledgeable about hypertension and survey methods. The quality of data is likely reliable. Finally, hypertension was determined by a combination of blood pressure measurement, self-report, and a hypertension registry.

In conclusion, hypertension knowledge levels are alarmingly low in rural areas of China, particularly concerning hypertension complications and medication. Many factors contribute to this low hypertension knowledge level, such as the availability of health education programs, economic conditions, and cultural background. Promoting national education levels should be a national priority, because illiteracy is still a common issue for this population and must be overcome in order to improve health education. Knowledge content deficiencies that we identified could guide development and improvement of educational programs for rural populations with the goals of increasing the awareness of hypertension, promoting blood pressure monitoring, and actively managing the disease.