Health literacy in Beijing: an assessment of adults’ knowledge and skills regarding communicable diseases

The study aimed to measure and assesses health literacy. Items for the questionnaire were identified following a review of the published research. Chinese studies that explored the knowledge attitude, and practices of participants related to infectious diseases prevention and control were reviewed for possible variables. In addition, variables from the National Health Literacy Survey [24‐27] that measured residents’ level of basic knowledge, adoption of preventative measures and behaviors, or health skills regarding common communicable diseases were extracted. In order to identify the most contextually appropriate variables, only studies conducted in Mainland China were utilized.

The items that were chosen for inclusion were discussed and evaluated by a small group of professionals, including three clinical doctors and three public health experts from the field of infectious diseases treatment and prevention. The three clinical doctors worked in the infectious diseases department of an infectious diseases hospital, a tertiary hospital and a secondary hospital within the Beijing region respectively, and the three public health experts were from Beijing Center for Diseases Prevention and Control (CDC), a district CDC office, and a community health center. Following the panel discussion, a total of 25 items were chosen for inclusion. The final questionnaire consisted of three sections that measured: knowledge (8 items), adoption of preventative measures and behaviors (12 items), and health skills (5 items).

The final survey was available in Chinese and took five to ten minutes to be completed. Values were assigned to each of the questions: (1) one point for a correct or positive answer; and (2) zero points if the answer to the question was incorrect or negative. For the item “How many days did you do physical activities more than 30 min per day in the past one week?” one point was assigned if participants answered “≥3 days”.

A multistage stratified sampling approach was used to recruit participants. In 2008, The National Health Literacy Survey showed the expected percentage of people with adequate health literacy was 21.82 % among city residents. The percentage was represented by symbol π and the numerical value was 0.2182 [17]. The sample size of each subgroup was calculated by the function n = μ_α² × π(1-π)/δ² × deff. The confidence interval (CI) was ±10 %, maximum permissible error (δ) =0.1π, μ_α = 1.96, and the design effect of complex sampling (deff) = 1.5, which was used to adjust the effectiveness loss of complex sampling instead of random sampling. Therefore the minimum sample size of each subgroup was 2,065. Considering the differences among different age groups (18–29, 30–39, 40–49, 50–59 and 60+), a total of five subgroups were identified. The total sample size of the five subgroups was expected to be 10,325 (2,065/subgroup × 5). Taking into consideration the response rates and efficiency rates of the questionnaire, the actual sample size was increased by 5 % to a total of 10,841.

There are 16 districts in Beijing, which are divided into urban and suburban districts based on population density. The population density was >6548 people per km² in the urban districts and ≤ 1305.4 people per km² in the suburban districts. Six districts including three urban districts and three suburban districts were chosen to be sampled. Five towns or streets were randomly selected in each district, and five resident committees or villages were randomly selected in each town or street. In total, 150 residents’ committees or villages were confirmed as survey locations. In every location, about 73 residents were randomly selected as subjects based on the name lists of residents acquired from residents’ committees. Participants were resident’s aged ≥18 years that were able and willing to give their informed consent to participate and who had continuously lived in Beijing for more than half a year. Participants were excluded if they were foreigners, residents of Hong Kong, Macau or Taiwan, or were unable to communicate in Mandarin.

The survey was conducted between December 2010 and January 2011. Participants were asked to complete the questionnaire by themselves or with the help of trained study staff if they had difficulty with reading or writing.

The database was established in Epidata 3.1, and analyzed using SPSS 11.5. Based on the score distribution, the average score of participants whose percentages were the closest to the top 25 % and bottom 25 % seperately were treated as the two cut points. The discrimination index (D) was calculated by taking the average score of the top 23.8 % of participants (PH, score ≥ 19) minus that of the bottom 22.9 % (PL, score ≤ 12). Reliability was calculated by internal consistency measures, using Cronbach’s alpha formula. Inter-scale correlations were calculated by the means of Pearson’s correlation coeffcients. Confirmation factor analyses were conducted to verify the scale’s construct validity. Confirmatory factor analysis was implemented by the Amos 7. Cut-point of adequate health literacy was determined via receiver operating characteristic (ROC) analyses based on their educational level. Frequencies were calculated for categorical variables. One-way ANOVA was used to compare the differences of health literacy scores between subgroups. The Pearson χ² test was used to compare the different proportions of respondents with CDHL in different groups. Multivariate unconditional logistic regression analysis was conducted to determine factors associated with the CDHL level. The variables with P < 0.10 in univariate analysis were included in multivariate analysis. Backward logistic regression was conducted by removing variables with P > 0.10. Statistical significance was defined as P < 0.05.

The study protocol was approved by the Research Ethic Committee of Beijing Center for Disease Prevention and Control.