A brief introduction of study site
All of the data analyzed in this paper was conducted in the Yuyao and Fenghua counties, which are in Ningbo city and located in the southeast of Zhejiang province. Zhejiang province is among the economically developed provinces in China (The GDP in Zhejiang province was 3231.885 billion in 2011, which was the fourth highest in China ). There were 3.27943 million farmers in Zhejiang province in 2011, and their mean net income was 13,017 Yuan/year, which was 1.87-times that of average income of farmers all over the country, and has been the highest among all the provinces in China for 27 continuous years . In the present survey, Yuyao and Fenghua, 2 counties with relatively high economical level (mean income for the farmers was 16,518 Yuan in 2011, which was the fourth among the counties in the province ) and large population of farmers (3.6823 million farmers in 2011, which was fourth among the counties in the province ).
Data were collected by face-to-face interview using the questionnaire recommended by the Ministry of Health with modifications suggested by the School of Public Health, Zhejiang University. All the investigators were recruited from the medical staff from the selected areas. All the investigators had participated in the previous 2 surveys, they were trained uniformly before the present investigation to ensure the quality. Stratified multistage cluster sampling was conducted to obtain the sample as follows: 5 towns were selected from each of the two counties, 2 villages were selected from each town, and then families were selected from each village. The final sample was from 2000 families in 20 villages of 10 towns in the 2 counties . To analyze the changes, the same villages were selected in the past three surveys. All the subjects included were permanent residents in the selected families. The sampling procedures in the present survey were identical to the ones used in the 4th National Health Services Survey, and had also been widely used in other studies (such as the Basic Health Service Project in Rural Areas and the Evaluation of New Rural Cooperative Medical System).
The questionnaire used in the 4th National Health Services Survey (2008 edition) was used in the survey to collect the data from the following aspects: 1) health service needs: including the socioeconomic characteristics, self-assessment of the health status, disease prevalence, disabilities, and health risk factors; 2) health service needs and utilization: including treatment for any disease, degree of satisfaction of demands, reasons for dissatisfaction; utilization of the public health services, maternal and child health care, outpatient and emergency departments, and hospitalization; and the payment of the medical expenditures; 3) medical insurance: including the composition of the medical insurance system, coverage of the medical insurance, range and level of compensation, and the operation of the major insurance systems; and 4) degree of satisfaction of the farmers with the service system, service providing processes, and the coverage and level of the medical insurance. The “illness within two weeks” in the present survey was defined as the self-assessment of presence of a disease based on the health care service aspect, and the subjects with at least one of the following characteristics were considered to be suffering from “illness within two weeks”: 1) felt uncomfortable in the past two weeks and referred to medical for treatment; 2) feel uncomfortable in the past two weeks, and self-prescribe some drugs or adjuvant therapies instead of referring to medical settings; 3) feel uncomfortable in the past two weeks but did not refer to medical settings or self-prescribe any treatments, and stopped working or stayed in bed for at least one day. The “two-week prevalence” was estimated with the “illness within two weeks”, and described as the percentage of the subjects with illness in the previous two weeks. The “two-week visiting rate” was estimated based on the frequency of the subjects visiting a healthcare facility for healthcare services in the previous two weeks due to discomfort, and described as the person-time of seeking medical care within the past two weeks. The “hospitalization rate” was estimated by the hospitalization of the subjects within the past one year, and was described as the person-time of hospitalization in the past one year due to illness.
Survey processes and quality control
As described, the questionnaire used in the 4th National Health Services Survey (2008 edition) was used for the data collection through face-to-face interview (Additional file 1). The survey was organized by the local health bureau and directed by a group in the Centers for Disease Control and Prevention (CDC) in each selected county. The health bureau of the county was in charge of the training of the investigators and directors, organizing the survey in the county, and the quality control of the survey. Trained investigators were asked to conduct face-to-face interview to collect the data with the questionnaire. The organization, direction, inspection, and quality control of the survey were conducted by the trained directors .
Data process and statistical analyses
Two investigators were asked to input the data with EpiData3.1 software independently. The data were checked and then output into an EXCEL database, and analyzed with SPSS 16.0 software. Chi-square test was used for the analyses. P ≤ 0.05 was considered statistically significant.