This was a population-based cross-sectional study involving adult population randomly selected. The City Bandundu is distant 400 km from Kinshasa is accessible by road via Mbakana or Mongata on the national 2. The Congo river being navigable in this part located upstream from Kinshasa, also allows access to the city tans by going up the river Kasai to the confluence of Kwilu and Kwango. By plane, the 230 km which separate the city of Bandundu from Kinshasa are covered in 45 minutes of flight.Study population and sampling
A multistage probability sampling method was used to estimate the sample size which was calculated using the formula: n ≥ (Z ^ 2 x (p) (1-p) ) / d ^ 2 where n = Sample size, z = 1.96 (confidence coefficient), p = previous prevalence, d = 0.05 (margin of error or range of imprecision reflecting the degree of precision absolute wanted). Because of the probable non-responding subjects, 10% of the number calculated at the height should be added. We estimated that hypertension reached 50% of households in the city of Bandundu, as prescribed in the literature, in the absence of a documented prevalence of such disease in the city. The sample size thus calculated was n≥ (1.96) 2x0.5x0.5 / (0.05) 2 = 384. By adding 10% of non-respondents, we obtained a size of 422. We multiplied the sample by 3 because of a population made up of different characteristics. This is what gave a height of 1266 housewives to interview. After questionnaire verification, a total of 1000 eligible people were successfully interviewed among households that gave their informed consent, resulting in a response rate of 79%.
Participants were included in the study if they were aged 18 years and above, living in Bandundu's city more than a year. Non-inclusion criteria included pregnancy.
Data for demographic and behavioral characteristics were obtained by self-reporting during face-to-face interviews. Demographic variables included items on gender, age, and marital status, level of education, employment status, hypertension duration and average monthly income.
The anthropometric measurements (such as body weight, waist circumference, height) blood pressure, and pulse rate were collected by well-trained Medical students. Blood pressure was measured using digital blood pressure measurement devices (OMRON MIT5 Connect, Kyoto, Japan) and recorded during household visits following the STEPS methods at the left arm at heart level after a period of 5 minutes of rest). The average of the two measurements were used in the analysis.
Height was measured, while the participants were in an upright position without shoes, by using a flexible tape meter (Hemostyl, Sulzbach, Germany). Body weight was also measured with individuals wearing light clothing or standing without shoes using adigital weighing scale (Deluxe GBS-721; Seca Deutschland, Hamburg, Germany). Body mass index (BMI) was computed as weight in kilograms divided by height in meters squared (Kg/m2). A flexible tape meter was used to measure the waist at the level directly above the iliac crest.
During the household visits, questionnaires on tobacco smoking and chewing, intake of fruit and vegetable and patterns of physical activities were administered. Participants were asked about their fruits and vegetables consumption in a typical week, number of days and the number of servings on those days was collected. Fruits and vegetable consumption was analyzed as number of times per week. The Global Physical Activity Questionnaire Version 2 was used to collect the information on physical activities [11].
Operational definitions
Hypertension was defined as either having a BP ≥ 140/90 mmHg and/or self-report of previous diagnosis of hypertension by a health care provider and/or if currently taking antihypertensive drug. Awareness as self-report of prior diagnosis by a health care provider among the participants with hypertension. Treatment of hypertension as using pharmacologic blood lowering medicines at the time of the interview among those aware of their hypertensive status. BP control BP < 140 mmHg while on treatment among those on treatment; isolated systolic, isolated and systolic-diastolic uncontrolled BP in treated patients were defined as SBP ≥ 140 mmHg and DBP < 90 mmHg, SBP < 140 mmHg and DBP ≥ 90 mmHg and SBP ≥ 140 mmHg and DBP ≥ 90 mmHg, respectively [12].
Diabetes was defined as fasting capillary blood glucose, 110 mg/ dl or history of antidiabetic treatment [13].
Low fruit/vegetable consumption of less than 5 portions of fresh and/or cooked fruits/vegetables a day [14]. The Global Physical Activity Questionnaire was used to collect information on physical activity. Insufficient physical activity was defined as self-reported less than 150 min of moderate intensive activity or less than 75 min vigorous intensive physical activity per week, including walking and cycling [11].
Body Mass Index (BMI): computed from the height and weight of the respondent - weight divided by height squared (Kg/m2). The BMI was further classified into four categories; underweight (BMI < 18.5 Kg/m2), normal (BMI 18.5-24.99 Kg/m2), overweight (BMI 25 -29.99 Kg/m2) and obese (BMI ≥ 30 Kg/m2 [15]. Waist circumference (WC) was used as surrogate for abdominal obesity, defined as a WC value > 94 cm in men and > 80 cm in women [16]. High cardiometabolic risk (CMR) as the waist-to -height ratio ≥ 0.5 [17].
Harmful use of alcohol was defined as consumption of more than 1 standard drink (which is the amount of alcohol you find in a small beer, one glass of wine, or one tot of spirits per day for females and more than 2 standard drinks for males [18]. Smoking was defined as current use of smoked or smokeless tobacco [19]. According to 2013–2014 DRC Demographic and Health Survey (DHS), low, middle and high socioeconomic status (SES) scores were defined as 0–3, 4–8 and > 9 respectively [20].
Statistical analyzes
Data were presented as the mean and standard deviation for the normally distributed continuous variables. the absolute and relative frequencies were used to illustrate the qualitative variables. The student's t test was used to compare group means. However, we used Pearson's chi-square or Fischer's exact test to compare the proportions. The factors associated with arterial hypertension were sought using a logistic regression test with calculation of the odds ratio and their confidence intervals finally to estimate the degree of association. p < 0.05 was the significance level statistical. Analyzes were performed using SPSS for Windows version 21 software.
Ethical approval
This research was conducted in strict compliance with the recommendations of the Helsinki Declaration III. The three principles of research ethics were respected, namely: respect for the human person, beneficence and justice. Respect for the human person was ensured by the anonymity system enshrined in the data collection sheets where the name was replaced by a code known only to the investigator (confidentiality required); beneficence was assured by the absence of morbidity associated with this study. Respect for justice was guaranteed by the free consent of the respondents to participate in the study and the right of the latter to withdraw from it at any time. All participants were informed of the objectives of the study, the conditions for participation and the procedure for clinical and para-clinical examinations. The research protocol for this study was submitted and presented to the medical ethics committee of the School of Public Health of University of Kinshasa and whose approval number is referenced ESP / CE / 054/2018.