|Year : 2017 | Volume
| Issue : 2 | Page : 36-44
Determinants of hypertension among adults in Tigray, Northern Ethiopia: A matched case–control study
Alemayehu Bekele Mengesha1, Susan Benedict2, Eva Kantelhardt3
1 Department of Research and Programs, n Public Health Association, Addis Ababa, Ethiopia
2 Global Health Program, University of Texas Health Science Center at Houston, Houston, Texas, USA
3 Department of Public Health, Martin-Luther University, Halle (Saale), Germany
|Date of Web Publication||18-Jul-2017|
Alemayehu Bekele Mengesha
Ethiopian Public Health Association, P. O. Box: 7117, Addis Ababa
Source of Support: None, Conflict of Interest: None
Background: Hypertension has become an epidemic and a global public health challenge resulting in considerable morbidity, mortality, and disability in human beings. There are reports indicating increasing magnitude of hypertension in Ethiopia. Despite this fact, less is known as for the determinants of hypertension.
Objective: To assess the determinants of hypertension among adults in Tigray, Northern Ethiopia.
Methods: A matched case–control study design was employed to identify the determinants of hypertension. A total of 117 cases and 235 controls were included in the study. Conditional logistic regression analysis was conducted to identify the determinants of hypertension.
Results: Low-income status, moderate work-related physical activity, shorter duration of alcohol use, and normal waist circumference were found to reduce the odds of hypertension. Poor perception on body size and mental stress was found to increase the odds of hypertension.
Conclusions: Multifaceted interventions including raising awareness and attitudinal changes on lifestyle modifications have to be intervened to prevent the risky behaviors by different actors.
Keywords: Behavioral, biological, determinants, hypertension, mental stress, perception, physical inactivity
|How to cite this article:|
Mengesha AB, Benedict S, Kantelhardt E. Determinants of hypertension among adults in Tigray, Northern Ethiopia: A matched case–control study. Int J Non-Commun Dis 2017;2:36-44
|How to cite this URL:|
Mengesha AB, Benedict S, Kantelhardt E. Determinants of hypertension among adults in Tigray, Northern Ethiopia: A matched case–control study. Int J Non-Commun Dis [serial online] 2017 [cited 2018 Jul 19];2:36-44. Available from: http://www.ijncd.org/text.asp?2017/2/2/36/211076
| Introduction|| |
Hypertension, also known as high or raised blood pressure, has become an epidemic affecting the health of many individuals and caused death toll globally.,,, Facts substantiating this are as follows: About 40% of adults over the age of 25 have hypertension; close to 20% of the population in the same age group were reported to have prehypertension; nine out of ten adults living to 80 years of age are expected to develop hypertension; and about 50% of these individuals may develop hypertension-related diseases and complications.,, Hypertension is reported to result in array of cardiovascular diseases (CVDs), namely, heart disease and stroke and kidney failure, premature mortality, and disability. The CVDs are responsible for about 17 million deaths every year accounting for nearly one-third of the total deaths globally. Of these deaths, complications of hypertension account for 9.4 million deaths every year. More specifically, hypertension is contributing for over 45% and 51% of deaths as the result of heart disease and stroke, respectively.
Hypertension disproportionately affects populations in low- and middle-income countries where health systems are weak to respond to noncommunicable diseases (NCDs). Two-thirds of people with hypertension are reported from low- and middle-income countries. More specifically, younger people are affected by heart disease and stroke in developing countries of the world than developed ones. High blood pressure was almost nonexistent in African societies in the first half of the twentieth century; however, the trend has totally been changed currently, and in some settings in Africa, >40% of adults have the problem. The magnitude of hypertension has raised significantly over the past two to three decades. Adults with hypertension were estimated to be 80 million in Sub-Saharan Africa in 2000 and projected to rise to 150 million by 2025 based on the available epidemiological data. Furthermore, evidence indicates that complications secondary to hypertension such as stroke and heart failure are also becoming pervasive in this region. Lifestyle changes such as increase in tobacco use, excessive alcohol consumption, reduced physical activity, and consuming diets that are high in salt, refined sugar, and unhealthy fats/oils were found to impact the trend of hypertension and related complications.
Overweight and/or obesity increase the risk of coronary cardiovascular disorders, including hypertension. As it has been reflected before, the number of hypertension cases is on increasing trend in Africa. Most of these cases could be managed with low-cost medications that would significantly reduce the risk of death and disability from heart disease and stroke.
In Ethiopia, hypertension was found to have greater prevalence compared to other risk factors for NCDs.,, A systematic review conducted based on the population-based studies in Ethiopia disclosed that the prevalence of hypertension varied widely, with the highest rate of 31.5% in males and the lowest rate of 0.8% in females, partly because of the differences in participants' mean ages, source population, and study settings. The review disclosed a high prevalence of hypertension in urban residents, and different associated factors including overweight, family history of hypertension, age, sex, sleeping for <5 h a day, oral contraceptive use, alcohol intake, physical inactivity, eating vegetables three or fewer days per week, salt use, obesity, higher education, and vigorous recreational activities were identified to be related with being hypertensive. Similar findings have been observed by a case–control study in India. Moreover, it was found factors such as cigarette smoking (including frequency and duration), alcohol misuse, physical activity level, restless sleep, increased body mass index (BMI), mental stress, mixed diet (animal and plant products), and salt intake were found to influence the odds of hypertension. In this study, the odds of developing hypertension was 3.23 times more likely among people who smoked 10 or more cigarettes than those who smoked fewer. Similarly, another hospital-based, case–control study conducted in India showed that study participants with family history of hypertension were 2.6 times more likely to have hypertension than those who reported to have no family history. The same study showed that obese study participants were 1.8 times more likely to develop hypertension than those with normal BMI. Another case–control study conducted in India showed that high and intermediate level and educational level and high socioeconomic status were found to increase the risk of hypertension (adjusted odds ratio [AOR]: 6.79, confidence interval [CI], 2.22–20.75) and (AOR: 14.04, CI, 4.25–46.33), respectively. Increased anxiety level in the study participants was found to increase the odds of being a case of hypertension, and consuming low-calorie diet was found to have protective effect for being a case of hypertension.
Based on the evidence to date in Ethiopia, hypertension is the leading risk factor for NCDs. If this risk factor is not prevented, it could result in morbidity, mortality, and disability of many people due to CVDs. To date, there is no established evidence on the risk factors for hypertension particularly in the study setting. To successfully tackle such a risk factor and its cardiovascular consequences, it is imperative to identify the determinants of hypertension so that sound public health preventive measures could be in place. Hence, this study aimed at unraveling the determinants of hypertension in the study settings.
| Methods|| |
The design of this study was a matched case–control. The matching variables were age and gender.
The study population consisted of all hypertensive cases (whose systolic blood pressure is ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg or those who were taking antihypertensive drugs during the study period) aged 25–64 years in Kilte Awlaelo Health and Demographic Surveillance Survey (HDSS) site and Mekelle city, Tigray, Northern Ethiopia. Controls were those residents in the study settings aged 25–64 years whose systolic blood pressure is <140 mmHg and/or diastolic blood pressure <90 mmHg during the study period and those who did not report a history of hypertension before and during the study period.
Before this study, a community-based, descriptive cross-sectional study was conducted and cases of hypertension/raised blood pressure were identified through measuring their blood pressure and interviewing for a history of hypertension. Hypertensive cases to be included in this study were selected randomly from those already identified cases during the cross-sectional study aforementioned. Controls were correspondingly selected randomly from residents in the same study settings who were found to be nonhypertensive both by history and/or physical measurement. Two controls were selected for each case after matching by age (within 2-year interval) and gender.
Sample size and characteristics
The desired sample size was calculated by standard sample size formula for unmatched case–control studies. Using 95% confidence level, 80% power, case to control ratio 1:2, expected frequency of hypertension among the control was 30.2% (16) and considered odds ratio (OR) closest to 1 is 2. Accordingly, 117 cases and 235 controls for 339 study participants were included in the study.
Data collection instruments, methods, and process
A questionnaire was developed to examine risk factors for hypertension after consulting the literature on risk factors associated with NCDs. Accordingly, 23 questions were developed to address the sociodemographic characteristics. For the behavioral and biological risk factors assessment, a total of 71 questions (using interviews and physical measurements) were used. The data collection methods were face-to-face interviews and physical measurements including weight (in bare feet without heavy clothing using Seca 767 digital scales), height (in bare feet without headwear using digital scales), waist circumference (WC) (at the narrowest point between the lower costal border and the iliac crest with a constant tension tape), hip circumference (at the greatest posterior protuberance of the buttocks with a constant tension tape), and blood pressure (at the midpoint of the left arm after participants rested for at least 5 min using an Omron T9P digital automatic blood pressure monitor). Two blood pressure readings were taken on all participants. A third reading was taken if there is a difference of >25 mmHg for systolic blood pressure or 15 mmHg for diastolic blood pressure between the first two readings. The mean of all measures was used to declare the presence or absence of hypertension. The data collectors were health professionals. Three days long training was provided to the data collectors and supervisors to equip them with basic knowledge and skills of data collection and related procedures for obtaining the physical measurements. Health professionals demonstrating adequate competency to the principal investigator were engaged in the main data collection process.
Quality control measures
The quality control measures employed in this study were training of data collectors and supervisors, conducting pretest of the study instrument to check for its clarity and appropriateness, and implementing close supervision during the field work.
Data management and analysis
EpiData statistical software (Epidata Inc. CDC) was used in this study for entry and cleaning. The cleaned data were then exported to SPSS version 20 (IBM® SPSS Statistics®) for data management and analysis. Descriptive statistical analyses including frequency distribution, measures of central tendency, and dispersion were computed. Results are presented in tables. Bivariate and multivariate analyses were employed to identify the independent predictors of the outcome variables. These analytical steps were done to outline the independent predictors of hypertension. To assess the presence of associations between dependent and independent variables, OR with 95% CI was computed.
The Ethical Review Board of the University of South Africa, Department of Health Studies, reviewed the proposal and provided ethical clearance. The proposal was submitted to the Ethiopian National Research and Ethics Committee, and ethical clearance certificate was obtained. A formal letter was sent to local institutions including the Tigray Region Health Bureau, Mekelle University, and other local administrative bodies including the Mekelle City and Kilte Awlaelo HDSS were consequently contacted to obtain permission to conduct this research in the setting.
The purpose of the study was explained to the members of the households and to the selected individual from each household to take part in the study. The interviews continued with the selected individuals after obtaining written consent. Confidentiality of the information given by the study participants was secured. Privacy of the study participants was maintained by interviewing the participants and taking their physical measurements in a private setting. In addition to these means of protection, unit identifiers were used to maintain anonymity of respondents' information.
| Results|| |
Sociodemographic characteristics of cases and controls
The sociodemographic characteristics of the participants for the matched case–control study have been indicated in [Table 1]. Thirty-four (32.7%) of the cases and 70 (67.3%) of the controls were from Kilte Awlaelo HDSS site. Eighty-three (33.5%) of the cases and 165 (66.5%) of the controls were from Mekelle city. Forty-seven (31.8%) of the cases and 101 (68.2%) of the controls were male. Seventy (34.3%) of the cases and 134 (65.7%) of the controls were female. Sixty-six (31.9%) of cases and 141 (68.1%) of controls were in the age group 25–44 years and the remaining 51 (35.2%) of cases and 94 (64.8%) of controls were in the age group 45–64 years. The median age of both cases and controls was 40 years (with interquartile range 33–50 years). By ethnicity, 111 (32.3%) of the cases and 233 (67.7%) of the controls were Tigre. The marital status of most cases 62 (30.5%) and controls 141 (69.5%) was married or cohabiting. Most cases 50 (37%) and controls 85 (63%) were in the first and second cycle education. The majority of the cases 51 (40.2%) reported their income to be > quintile 1 and ≤ quintile 2 and most controls 91 (74.6%) reported to have monthly income of ≤quintile 1. Most of the cases 49 (40.5%) and controls 73 (76.8%) were self-employed and formally employed, respectively. The predominant religion for both cases 111 (33.1%) and controls 224 (66.9%) was orthodox Christianity.
|Table 1: Sociodemographic characteristics of the study participants on determinants of hypertension in Kilte Awlaelo Health and Demographic Surveillance Survey site and Mekelle city, Tigray, Ethiopia, January 2014|
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Sociodemographic determinants of raised blood pressure or hypertension
The sociodemographic determinants of hypertension were assessed using binary logistic regression analysis for hypertension as indicated in [Table 2]. Sociodemographic variables having a P ≤ 0.25 on crude analysis were fitted into the final model to identify the independent predictors after adjustment. Accordingly, only four variables “ marital status, occupation, income, and religion “ were found to be eligible. Income of ≤ quintile 1 had 90% reduced risk of being a case of hypertension as compared to those whose income was greater than quintile 4, AOR and 95% CI, 0.1 (0.004–0.84). The remaining variables did not have statistically significant association with being a case of hypertension.
|Table 2: Sociodemographic determinants of hypertension among the study participants in Kilte Awlaelo Health and Demographic Surveillance Survey site and Mekelle city, Tigray, Ethiopia, January 2014|
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Behavioral determinants of raised blood pressure or hypertension
The behavioral determinants of hypertension have been indicated in [Table 3]. Variables having a P ≤ 0.25 with being a case of hypertension on crude or bivariate analysis and those believed to have a biological relationship were fit into the final model after adjusting for potential confounders. Accordingly, participants engaged in vigorous work-related physical activity were 2.5 times more likely to be a case of hypertension than those who did not engage in such physical activity, OR and 95% CI, 2.5 (1.11–5.61). In contrast, there was 50% reduced risk of being hypertensive among participants who were engaged in moderate work-related physical activity as compared to those who did not engage in such activities, OR and 95% CI, 0.50 (0.25–0.99). Drinking alcohol for <10 years duration had 70% reduced risk of being hypertensive as compared to those who drank alcohol for ≥10 years duration, OR and 95%, CI, 0.30 (0.15–0.59). The remaining explanatory variables were not found to be statistically associated with being hypertensive.
|Table 3: Behavioural determinants of hypertension among the study participants in Kilte Awlaelo Health and Demographic Surveillance Survey site and Mekelle city, Tigray, Ethiopia January, 2014|
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Physical measurement determinants of raised blood pressure or hypertension
The physical measurement determinants of hypertension have been indicated in [Table 4]. Variables having a P ≤ 0.25 with being a case of hypertension on crude or bivariate analysis and those believed to have a biological relationship were fit to the final model after adjusting for potential confounders as it has been done for other determinants. Three variables “ BMI, WC, and waist to hip ratio (WHR) “ were fit into the final model of binary logistic regression. Having normal WC had 42% reduced risk of being hypertensive compared to those whose WC was raised, OR and 95% CI, 0.58 (0.34–0.98). BMI and WHR did not have statistically significant associations with hypertension when fitted to the final model although they had statistically significant differences on crude or bivariate analysis.
|Table 4: Physical measurement determinants of hypertension among the study participants in Kilte Awlaelo Health and Demographic Surveillance Survey site and Mekelle City, Tigray, Ethiopia, January 2014|
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Perception-related determinants of raised blood pressure or hypertension
The perception-related determinants of hypertension have been indicated in [Table 5]. Variables having a P ≤ 0.25 with being a case of hypertension on crude or bivariate analysis and those believed to have a biological relationship were fit to the final model after adjusting for potential confounders. The study participants who reported that they did not lose weight after perceiving or being told that they were overweight or obese were 6.72 times more likely to be hypertensive compared to those wanted to lose weight, OR and 95% CI, 6.72 (3.14–14.4). The participants who responded that being overweight or obese has an adverse health consequence were 6.63 times more likely to be hypertensive compared to those who did not know anything, OR and 95% CI, 6.63 (1.1–40.80).
|Table 5: Perception.related determinants of hypertension among the study participants in Kilte Awlaelo Health and Demographic Surveillance Survey site and Mekelle City, Tigray, Ethiopia, January 2014|
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Mental stress-related determinants of raised blood pressure or hypertension
The mental stress-related determinants of hypertension have been indicated in [Table 6]. Variables having a P ≤ 0.25 with being a case of hypertension on crude or bivariate analysis and those believed to have a biological relationship were fit to the final model after adjusting for potential confounders. The study participants who thought they had have poor digestion had 61% reduced risk of being hypertensive compared to those who did not feel so, OR and 95% CI, 0.39 (0.20–0.75). The participants who felt nervous, tense, or worried were 1.63 times more likely be hypertensive compared to those who did not feel nervous, OR and 95% CI, 1.63 (1.0–2.75). The participants who lost interest in things in their immediate environment were 5.46 times more likely to be hypertensive than those who did not have similar feelings, OR and 95% CI, 5.46 (1.47–20.2). The other variables did not have statistically significant difference when fitted into the final model.
|Table 6: Mental stress determinants of hypertension among the study participants in Kilte Awlaelo Health and Demographic Surveillance Survey site and Mekelle City, Tigray, Ethiopia, January 2014|
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| Discussion|| |
This particular study identifies various determinants of hypertension among Ethiopian adults 24–64 years. These determinants include sociodemographic characteristics, behavioral factors, physical measurements or biological factors, perception-related factors, and variables for measuring mental stress.
The study participants with low income were found to have reduced risk of being a case of hypertension compared to those with the higher income. This is consistent with the study findings observed between hypertension and income status in Bangladesh and India.
Although a sedentary lifestyle is frequently associated with hypertension, in this study, participants who were engaged in vigorous work-related physical activities were more likely to be hypertensive compared to those who did not engage in such physical activities. The vigorous work-related physical activity could be related to a stressful situation which might have precipitated a raised blood pressure. However, there was reduced risk of being hypertensive among participants who were engaged in moderate work-related physical activity as compared to those who did not engage in such activities. Drinking alcohol for shorter duration of time was found to reduce the risk of acquiring hypertension. Except the finding on work-related vigorous physical exercise, the above findings are consistent with the findings of two studies in India.
The sole physical measurement found to be statistically associated with being a case of hypertension was WC. The study participants with WC in the normal range had a lower risk of being hypertensive than those whose WC was elevated. This finding is also consistent with studies in India, and other evidence observed and reported in Africa.
Perception-related factors were also assessed. The study participants reported that they would maintain their body weight even if they perceived or were informed that they were overweight or obese were more likely to be a case of hypertension compared to those who reported that they would plan to reduce their body weight. This indicates that wrong perception on body weight may have increased the odds of acquiring hypertension. The study participants who responded 'Being overweight or obese had adverse health consequences' were more likely to be hypertensive than those who did not know the adverse consequences of being obese or overweight. This could be explained by exposure to prior information on the adverse consequences of overweight or obesity among the hypertensive cases than controls.
Mental stress-related factors were assessed to identify their relationship with hypertension. The study participants who had a feeling of having poor digestion had reduced risk of being a case of hypertension compared to those who did not feel so. The study participants who felt nervous, tense, or worried were more likely to be a case of hypertension than those who did not feel nervous. The study participants who lost interest in things in their immediate environment were more likely to be hypertensive than those who did not have similar feelings. This is consistent with the findings in different studies India., In general, in this study, we learned that there is a range of factors which could underlie hypertension.
This study has its own strengths and limitations. The fact that large sample size was used and matching by age and gender was employed among the cases and controls enabled to maintain its validity and minimize confounding factors. The limitation could be recall and social desirability biases (might mask the association between the risk factors identified and being a case of hypertension) among the study participants when reporting some behavioral risk factors.
| Conclusions|| |
Based on the result of this study, different predictors of hypertension were outlined. Higher income, being engaged in vigorous work-related physical activities, drinking alcohol for 10 years or more, raised WC, having poor perception on the consequences of overweight and obesity, and having mental stress including feeling of nervousness and loss of interest in things were found to increase the odds of being a case of hypertension. On the other hand, being engaged in moderate work-related physical activity and having poor digestion were found to decrease the odds of being a hypertensive case. Furthermore, both moderate and vigorous sport-related activities were negatively associated with hypertension on bivariate analysis but did not show a statistically significant association on multivariable analysis. Hence, recommendations are highly warranted based on the findings revealed by this study. Alcohol misuse and longtime consumption should be avoided, and drinkers should be supported to eliminate such behaviors. Central obesity has to be prevented to minimize the risk of hypertension and people with increased WC have to be advised to start on healthy lifestyle measures such as leisure time physical activities, avoiding harmful use of alcohol, and other behavioral risk factors. The relevance of managing and preventing mental stress and its underlying causes has paramount importance in reducing the occurrence of hypertension and its cardiovascular consequences. Awareness raising interventions in the general community with special emphasis on people in the higher social class should be given due attention in preventing hypertension. Leisure time physical activities should be practiced by the general public, and all partners should create conducive environment for its implementation. Further research should be conducted to provide further evidence to identify additional factors underlying hypertension.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]