Sampling collection
In total, 472 Bai ethnic elderly patients with hypertension, aged 60 years old or above, from 5 Bai rural communities of Yunnan province were recruited in this study using a multi-stage stratified sampling method and were face-to-face interviewed by trained researchers from Kunming Medical University of Yunnan province who could speak both Mandarin and Bai language. Inclusion criteria were as follow: Bai elderly aged 60 and above; hypertension diagnosis more than 6 months; at least one antihypertensive medication for the past 6 months; the mental ability to answer the interview questionnaire. The Bai ethnic hypertensive patients who did not take antihypertensive medication, or were diagnosed with hypertension less than 6 months, or live with serious hypertension complications such as stroke, paralysis were excluded from this research. The interviews were a series of questions and scales, for example, age, education level, course of hypertension, family history of hypertension, health-promoting lifestyle profile (HPLP), the exercise of self-care Agency scale (ESCA), and the MOS item short-form health survey (SF-36).
Ethical considerations
The protocol of this study was approved by Kunming Medical University and the local government from the beginning of the research. Written and verbal informed consent were obtained from all participants who were volunteering before this survey. All personal information of the participants was assured to be kept confidential.
Measurement instruments
Health-promoting lifestyle profile II(HPLP-II) is a widely used instrument to evaluate an individual’s health behaviors and lifestyles, which showed good validation and reliability in multiple studies [17, 18]. It composes 6 aspects of health promotion behaviors and lifestyles, namely, health responsibility (9 items), physical activity (8 items), nutrition (9 items), spiritual growth (9 items), interpersonal relationships (9 items), and stress management (9 items). Each item is answered with four choices: never, sometimes, often, with a score of 1, 2, 3, and 4. The total score of health promotion lifestyle is divided into 4 grades, which are “Low”(52–90 points), “Average” (91–129 points), “Good” (130–169 points), and “Excellent” (170–208 points) respectively [19]. The internal consistency reliability of HPLP -II in this research is 0.939, and the Cronbach’s α coefficient of each subcategory of HPLP -II were 0.900, 0.860, 0.857, 0.901, 0.930, 0.942, respectively.
The Exercise of Self-Care Agency Scale (ESCAS) was chosen to measure the Self-care ability of hypertension in the Bai ethnic elderly. The ESCAS has been proven to have high reliability and validity in some international studies [20]. The scale consists of 43 items that assess the extent of self-care abilities of individuals on a 5-point Likert scale ranging from 1 = completely un-similar to me, while 5 = completely similar to me. The ESCA is divided into 3 levels according to the total score (172 points) of the scale: a high level indicating more than 66% of the total score, 33-66% of the total score for a medium level, a low level less than 33% of the total. Subjects with scores less than 33.3% (≤ 56), 33.3–66.6% (57–114), and more than 66.6% (≥ 115) of the total score are considered with low, moderate, and high self-care agency, respectively. The higher score indicates better self-care agency. The Cronbach’s α coefficient of the ESCA scale in this study was 0.891.
Health-related quality of life is an individual’s subjective perception of physical, psychological, social and emotional well beings and a comprehensive indicator that comprehensively reflects the individual’s health status. The SF-36 scale is widely used to measure the quality of life in the general population. The SF-36 scale consists of eight areas: physical functioning (PF), role limitations relating to physical health (RP), bodily pain (BP), general health perception (GH), vitality (VT), social functioning (SF), role limitation relating to emotional health (RE) and mental health (MH). The Physical Component Summary includes PF, RP, BP, GH and Mental Component Summary contains VT, SF, RE, and MH. The score of each domain ranges from 0 to 100, with higher scores indicating a better-perceived quality of life [21]. According to the grading cut-off point of the Chinese version of the SF-36 scale recommended by Zhang Lei as the classification standard, the total score is greater than 117, indicating that the research object is in good condition; and the total score is in the range from 72 to 117, indicating that the research object is in moderate condition; and the total score below 72 indicates that the research subjects are in poor condition [22]. The Cronbach’s α coefficient of SF-36 scale in this study was 0.882, and the Cronbach’s α coefficient of Physical health and Mental health aspects of SF-36 scale were 0.826 and 0.869, respectively.
Other variables
Other variables in this survey included the self-designed social-demographics questions, such as age group, gender, educational background, course of hypertension, complications, family history of hypertension, and types of antihypertensive drugs. The Bai ethnic elders were divided into five age groups (60–64, 65–69, 70–74, 75–79, and 80 years and older) based on our past meaningful findings. Education background was classified into four categories: illiterate, primary school, junior high school, and senior high school and above. There were three categories of course of hypertension, including less than five, five to ten, and ten and above. There were three categories of types of antihypertensive drugs, including one, two, three, and above. “Yes” or “no” choices were given to the participants to answer whether they had complications and a family history of hypertension.
Statistical analysis
Epidata 3.1 was used to establish the database and Statistical Package for Social Sciences (SPSS) version 22.0 was used to analyze the collected data. Descriptive statistics such as means and standard deviations were utilized to express the statistical results of continuous variables, while proportions and frequencies were applied to show categorical variables. ANOVA was used to examine the statistical differences of variables among different age groups. Pearson correlation analysis was used to analyze the associations among SF-36 and HPLP-II, ESCA in the sampling population. Multiple linear regression analysis was utilized to assess the associations of HPLP-II, ESCA, and other socio-demographic variables on SF-36, by utilizing the total score of SF-36 as a dependent variable. A P value of less than 0.05 was considered statistical significance.