Comorbidities of diabetes and hypertension in Vietnam: current burden, trends over time, and correlated factors – BMC … – BMC Public Health

Data sources and survey populations

This analysis combined data from 3 STEPs surveys in Vietnam. The sample size, sampling method, and study subjects (i.e., aged from 18 to 69 years old) were similar for the STEPs 2015 and 2021. The two recent rounds applied two stage-random systematic sampling methods (i.e., the primary sampling unit was Enumeration Areas) with a sampling frame consisting of 15% of the population of Vietnam and representing all 63 provinces and cities. In STEPs 2015, the final sample size for STEPs 1, 2, and 3 was 3,758 (response rate 97.4%), 3,036 (response rate 78.7%), and 2,816 (response rate 73.0%), respectively. In STEPs 2021, the sample size included 4,738 subjects in STEP1 (response rate of 94,76%) and 3,712 subjects in STEPs 2 and 3 (response rate of 74.2%). The 2010 survey applied a three-stage sampling method and only collected data from 8 provinces, representing 8 ecological regions of Vietnam.

The random sampling method was conducted as follows. In the first stage, utilizing the master sample frame of the General Statistics Office of Vietnam, two stratifications were created: (1=urban; 2=rural, and within each group divided into 3 sub-groupscoastal, lowland, and mountainous, resulting in 6 strata). In each stratum, the sampling of Primary Sampling Units (PSUs) applied the probability proportional to size (PPS) sampling method to select the required number of Enumeration Areas (EAs) in that stratum. During the second stage of sampling, households in each selected EA were chosen randomly from the sampling frame of the EAs. Subsequently, one eligible person was randomly selected from each chosen household for the STEPS 1 interview. The selection of this individual is automatically executed by the Android tablet program after eligible household members are entered into the Android tablet.

The study subjects in this round only include people aged 2564 years old. The survey sample size in STEPS 2010 was 14,706 people. Panel data for 3 waves of STEPs were constructed in this study. As the subjects age-selected criteria differed across the three STEPs, we selected data for the population aged 2564. Figure1 shows the derivation of study samples from datasets. After applying the exclusion criteria, the study samples comprised 19,380 observations for the analyses.

Derivation of the study sample

defined as an average of three measured systolic blood pressures (SBP)140 mmHg, and/or an average of three measured diastolic blood pressure (DBP)90 mmHg, and/or self-reported previous diagnoses of hypertension by a health professional, and/or self-reported current treatment for hypertension with antihypertensive medications in the previous 2 weeks [13].

defined as measured blood sugar (plasma venous value) 7mmol and/or who were currently on medication for diabetes [13].

a person having both hypertension and diabetes.

A categorical variable with 4 classes, 2534 years old, 3544 years old, 4554 years old, and 5564 years old.

a binary variable (1 for urban and 2 for rural).

BMI was calculated as weight (kg)/height2 (m). High BMI was defined as subjects with a BMI score equal to or greater than 25.

A categorical variable (ranging from 0 to 4) combining 4 NCD behavioral risk factors (i.e., current smoking, current drinking, not meeting levels of physical activity recommended by The World Health Organization (WHO), and not consuming enough vegetables/fruit per day). The 4 NCD risk factors were defined as follows: (1) Current smoking: Respondents were asked the question, Do you currently smoke tobacco on a daily basis, less than daily, or not at all? and were defined as current smokers if the participants chose currently smoke tobacco daily or less than daily; (2) Current drinker: respondents were defined as current drinker if they consumed at least one standard drink of alcohol thin the past 30 days; (3) Not enough physical activities (PA): WHO recommendation on PA for health was throughout a week, including activity for work, during transport and leisure time, adults should do at least an equivalent combination of moderate- and vigorous-intensity physical activity achieving at least 600 Metabolic Equivalent of Task (MET)-minutes, so a person with total PA score in METs less than 600 MET-minutes in this study was defined as not meeting WHO recommendation; (4) Not eating enough fruit/vegetable: consuming less than 5 serving of fruit/vegetable per typical day.

The SVY procedure in STATA 18 was used to estimate the overall prevalence of hypertension, diabetes, comorbidity, and their 95%CI for the years 2010, 2015, and 2021. Survey weights were used for all calculations. The trends of T2DM-HTN comorbidity across subgroups of age, gender, and geographic area were also estimated. Multiple logistics regression was applied to examine correlated factors for the outcome of T2DM-HTN comorbidity. Independent variables examined in the model included survey year, age group, gender, location, BMI score, and the number of NCD behavioral risk factors. The variables for inclusion in the multivariate model were chosen using two criteria: either a p-value of the bivariate association with the outcomes<0.2 or the variables were deemed of biological importance (e.g., gender). Two modeling strategiesenter (i.e., including all variables in the model simultaneously) and stepwise (i.e., iteratively adding or removing potential explanatory variables and testing for statistical significance after each iteration)were assessed. Both models produced identical results; therefore, the findings from the model employing the enter method were reported. A p-value<0.05 was considered statistically significant.

As the outcome focused on the comorbidity of T2DM-HTN, the inclusion of individuals with a single disease (i.e., either T2DM or HTN) in the comparison group could potentially impact the strength of the association between NCD behavioral risk factors and the outcome. Therefore, a sensitivity analysis was conducted, comparing two models:

Model (1) utilized the entire dataset, where the outcome was comorbidity, and all individuals with only one status (either diabetes or hypertension) were placed in the group with no outcome (sample size=19,380 subjects).

Model (2) used data exclusively from individuals with comorbidity and those with neither hypertension nor diabetes (individuals with either disease were excluded from the analysis, sample size=14,941 subjects).

Both models revealed the same significant predictors, with the odds ratios (ORs) in the second model slightly higher. However, given that the study objective was to identify correlated factors of comorbidity, the results of the first model were reported. We also checked the autocorrelation in a final regression models output with the Durbin-Watson (DW) test, the DW statistic was equal to 1.79, indicating zero autocorrelation.

The paper was based on secondary data from the STEPS 2010, 2015, and 2021, with all identifying information removed. All procedures performed in STEPs involving human participants were in accordance with the ethical standards of The Ethical Review Board for Biomedical Research. The original STEPS surveys were approved by the Ethics Committee of the Vietnam Ministry of Health and the Tasmanian Health and Medical Human Research Ethics Committee in 2010 and the Hanoi School of Public Health in 2015 and 2020. All information on the original dataset was collected confidentially.

Excerpt from:
Comorbidities of diabetes and hypertension in Vietnam: current burden, trends over time, and correlated factors - BMC ... - BMC Public Health