The study investigated the health literacy levels, their distribution characteristics and their influencing factors in China. Health literacy was measured using the National Resident Health Literacy Monitoring Questionnaire. MapInfo software was used to map the geographic distribution. Multiple logistic regression was used to adjust for the factors associated with the health literacy level in the total and regional samples. The study subjects were permanent residents aged 15-69 years who had continuously lived in the survey areas for more than 6 months.
The research protocol was reviewed and approved by the Medical Ethics Committee of Central South University. All participants (aged 16 and upwards) who agreed to participate in the study signed an informed consent form at the beginning of the survey. Written informed consent was obtained from a parent or guardian for participants under 16 years old.
There are 34 provincial administrative regions in China. After comprehensively considering factors such as geography, economic level, population, accessibility of investigation capacity, project funding, etc., 25 provinces were non-randomly selected for investigation. Multi-stage stratification, clustering, and random sampling methods were used to randomly select a total of 70 survey points nationwide among the 25 provinces or municipalities (6 in the eastern region, 8 in the central region, and 11 in the western region) in China, with the selection of 1-2 urban and rural survey points in each province according to regional and population factors, followed by the random, step by step selection of the sample areas (counties), streets (townships) and neighbourhood committees (villages). Furthermore, 50 households were randomly selected from each community according to the community's resident roster, and then one eligible respondent was randomly selected from each selected household. The sample size (N = 2419) was calculated to ensure a proportion estimation of adequate health literacy with α = 0.05 based on a conservative assumption of a 15% proportion.
The social demographic characteristics included gender, age, place of residence, community type, marital status, education level, and economic status. According to the region classification in the China Health Statistics Yearbook, the surveyed residences were divided into the eastern, central, and western regions. Based on 75% and 125% of the median annual household income per capita, economic status was divided into the poor, medium, and good categories.
The National Resident Health Literacy Monitoring Questionnaire (NRHLMQ), prepared by the China Health Education Center, was used to measure health literacy. The overall Cronbach’s alpha of the NRHLMQ was 0.95, and the Spearman-Brown coefficient was 0.94 . Confirmatory factor analysis showed that the questionnaire measured a unidimensional construct with three highly correlated factors . It included three dimensions: (1) basic knowledge and attitudes (BKA), (2) healthy lifestyles and behaviours (HLB), and (3) health-related skills (HRS). The NRHLMQ covered six domains: scientific views of health (SVH), prevention and treatment of infectious diseases (PTID), prevention and treatment of chronic diseases (PTCD), safety and first aid (SFA), basic medical care (BMC), and health information (HI).
There are three types of questions in the NRHLMQ: true or false (1 point for each correct response), single answer (only one correct answer in a multiple-choice question, 1 point for each correct response), and multiple answer (more than one correct answer in a multiple-choice question, 2 points for each correct response). For the multiple-answer questions, the correct response had to contain all of the correct answers and none of the wrong ones.
The total score of the NRHLMQ is 66 points, with the total scores of the three dimensions being 28 (BKA), 22 (HLB), and 16 (HRS) points. The total scores of the SVH, PTID, PTCD, SFA, BMC, and HI are 11, 7, 12, 14, 14, and 8 points, respectively.
A total score of 53 (80% of 66) points and above was determined to indicate adequate health literacy (adequate HL). A score of 0 to 52 was considered as limited health literacy (limited HL). The health literacy level was defined as the proportion of participants who had adequate health literacy out of the total number of participants. The judging criteria for adequate HL in each dimension or domain were ≥ 80% of the total score of the dimension or domain [12-13].
The self-evaluation health status was used as the evaluation index, which was divided into the good, fair, and poor levels. In addition, the original question was, "In the past year, what do you think of your health status?"
Community health education
We used the number of health talks to assess community health education, and the original question was, "What is the number of health talk in your community in the past three years?" The self-reported frequency of participation in community health talks in the past three years was divided into three categories (0 times, 1-9 times, and ≥10 times).
In the pre-investigation stage, a certain number of respondents were randomly selected from the sample locations for pre-surveys, focusing on whether the questionnaire entries could be understood and whether ambiguity was generated. The results showed that the respondents could understand the contents of the questionnaires. In the formal investigation phase, individual interviews were used to collect information. In the re-testing phase, which was two weeks after the formal investigation, the investigators re-tested 155 respondents who were selected using a random number table according to numbers assigned to the questionnaires. All stages of the investigation were completed by undergraduate students majoring in preventive medicine. Prior to the investigation, all investigators were given uniform training for this survey. The investigation was conducted from January to April 2017.
Statistical analysis was conducted with SPSS version 19.0 (IBM Corp., Armonk, NY, USA) and MapInfo Professional version 7.0 (Pitney Bowes MapInfo Corp., Stamford, USA). The integrity check was done before submitting the questionnaire, and questionnaires with missing values were not included in the analysis (there were 3 questionnaires with missing values). Prior to the analysis, data were screened for outliers and out of range values. No outliers or out of range values were found. The general conditions and health literacy of the sample were statistically described as the mean ± standard deviation, composition ratio, median, and frequency distribution table. To evaluate the factors of health literacy, the health literacy score was dichotomized into two categories: adequate and limited. The chi-square (χ2) test was used to compare the health literacy levels among different characteristic groups. The geographic variations of health literacy levels were described using MapInfo software, and the National Platform for Common Geospatial Information Services of China provided the map. A series of multiple logistic regressions was used to adjust for the relevant factors associated with the health literacy level in the total and regional samples. The logistic regression analyses were performed with gender, age group, marital status, community type, education level, economic status, self-rated health status, and frequency of participation in community health education as the independent variables; adequate health literacy served as the dependent variable in the total and regional samples. An adequate HL equation was established using a multiple logistic regression model with the stepwise forward (LR) method. The results of all hypothesis tests with p-values<0.05 (two sided) were considered statistically significant.