Prevalence and associated risk factors of hypertension among adults in Akure-South local government area, Akure, Ondo State, South-West Nigeria

¹Department of Family Medicine, University of Medical Sciences Teaching Hospital Complex, Ondo State, Nigeria, ²Department of Nursing Sciences, Afe Babalola University Hospital, Ado-Ekiti, Ekiti State, Nigeria, ³Department of Ophthalmology, University of Medical Sciences Teaching Hospital Complex, Ondo State, Nigeria, ⁴Department of Radiation and Clinical Oncology, University of Medical Sciences, Ondo State, Nigeria, ⁵Department of Medical Microbiology, Federal Medical Centre, Owo, Ondo State, Nigeria, ⁶Pharmaceutical Department, Ilesha, Osun State, Nigeria, ⁷Ministry of Health, Ondo State, Nigeria

^&Corresponding author
Adewale Oluwafemi Ayadi, Department of Family Medicine, University of Medical Sciences Teaching Hospital Complex, Ondo State, Nigeria

Introduction    

Globally, high blood pressure is the major cause of cardiovascular diseases and its related mortalities [1,2]. In addition to rising in economic crises, social insecurity, and financial challenges, hypertension has been on the increase and constantly resulting in high cardiovascular morbidity and mortality [3]. The cause of most primary hypertension is quite uncertain, however, the majority of the risk factors have been linked. These risk factors are basically divided into modifiable and non-modifiable factors [3-5]. The modifiable risk factors are as follows; unhealthy diets, high intake of salt, obesity, smoking, poor physical activity, high intake of alcohol, and poor stress control. The non-modifiable factors are; age, race, gender, and hereditary or family history of hypertension [3]. The rate of exposure to some of these risk factors especially in the urban cities has led to the high prevalence of hypertension. As a result of this, the study aims to determine the prevalence of hypertension and its related risk factors among the adults residing in Akure South Local Government Area (LGA), Akure, Ondo State. This shows the need to have early screening, management, and prompt decision-making, especially in the community of the country in order to reverse the burden of hypertension.

Research questions

This study sought answers to the following research questions: 1) What is the prevalence of hypertension among adults living in Akure South local government area? 2) What are the associated risk factors related to hypertension among adults living in Akure South local government area? 3) What is the association between the risk factors and hypertension among adults living in Akure South local government area? 4) What are the predictors of hypertension among adults living in Akure South local government area?

Methods     

Study design and setting: this study was a descriptive cross-sectional community-based study. It was carried out to determine the prevalence of hypertension and associated risk factors among adults (18 years and above) in Akure-South local government area. Akure South Local Government Area (LGA) is the most populated LGA in the state with different socio-demographic variations. Akure South local government area is one of the six (6) local government areas under Ondo Central Senatorial District, and one of the eighteen (18) LGAs in Ondo State. Akure South LGA has an area of 331 km² and a population of 360,268 (10.41%) as of the 2006 census [6]. Akure South LGA is bounded by Akure North LGA on the North-East and by Ifedore LGA on the North-West, while on the Southern part by Idanre LGA. The aboriginal people are of the Yoruba tribe, although there are other tribes like Igbo, Hausa, Edo, Igbira, among others. Major economic activities include farming, trading, and civil service. Akure South LGA has eleven (11) wards which are Aponmu, Gbogi/Isikan l, Gbogi/Isikan ll, Ijomu/Obanla, llisa, lrowo, Oda, Odopetu, Oke-Aro, Oshodi/Isolo, and Owode/Imuagun.

Study population: the study population comprised of consented adults aged 18 and above who reside in Akure South Local Government Area, Akure, Ondo State, who satisfied the inclusion criteria while others such as individuals below 18 years of age, physically or mentally sick adults and pregnant women participants were excluded. The data collection was within 3 months from December 2022 to February 2023, using a multi-stage random sampling technique. There were three stages and for each stage, different sampling design was used. In the first stage, out of the 11 wards, 6 wards were selected by using simple random sampling. In the second stage, from each selected ward, 50% of the streets were selected, and in the third stage, the households in the streets were further selected by using systematic random sampling.

Inclusion criteria: adults of age 18 years and above; consented voluntarily to partake in the study by signing a consent form. He or she must be living in Akure-South local government for at least six months and should be healthy.

Exclusion criteria: the pregnant or breastfeeding women; critically sick; visitors temporarily staying in Akure-South local government.

Sample size estimation: the sample size of the study was 420 calculated using Leslie Kish´s formula for determining minimum sample size for health studies used by Fisher (Singh AS et al.) [7].

Where n = desired sample size, z = standard normal deviation, d = degree of accuracy, p = estimated prevalence, and q is 1-p. The study used was by Odili et al. on the prevalence, awareness, treatment, and control of hypertension in Nigeria: data from a nationwide survey 2017 [8]. Thus, a sample size of 420 adults was used for this study.

Variables and instruments: variables were assessed using semi-structured and structured questionnaires. The semi-structured questionnaire was done by the authors while obtaining the data on socio-demographic features. The data was collected by asking respondents to fill out the questionnaires and assisted by trained research assistants where necessary using only two WHO STEPS instruments (socio-demographics and the risk factors and the Physical measurements of height, weight, Body Mass Index (BMI), and blood pressure) [9]. Additionally, participants´ weight, height, and Blood Pressure (BP) were measured according to standard procedures.

Blood pressure: to estimate the prevalence of hypertension among adults living in the Akure South local government area, we assessed the mean value of the first and second blood pressure measurements were considered as the participant´s blood pressure. The mean of the first and second measurements was considered as the subject´s blood pressure. Two consecutive measurements were taken on the left arm of the respondent. The average blood pressure of each patient was classified as follows: normal value as 120/80 mmHg, pre-hypertension as 120-139/80-89 mmHg, hypertension as 140/90 mmHg and above, stage 1 hypertension as 140-159/90-99 mmHg and stage 2 hypertension as 160/100 mmHg and above. Blood pressure measurement: blood pressure was measured using a standard digital sphygmomanometer (andon Digital Blood Pressure Monitor Sphygmomanometer, KD-595); iHealthLabs, made in China; recommended for clinical use in adults [10] on the upper arm with back support after the study respondent rested for at least 5 minutes.

Weight: to identify the risk factors of high blood pressure among adults living in the Akure South local government area, we measured the weight of the subjects to the nearest 0.1 kilogram (kg) with light clothes on and without foot wears and accessories using Hana´s bathroom weighing scale. The weighing scale was used after calibration with known standard weight; and adjusted for zero error before each weighing. They were then asked to step onto the scale with one foot on each side of the scale as indicated, without covering the scale calibration. The participant then stood still, faced forward, placed arms on the side, and waited until asked to step down. The scale was externally recalibrated daily.

Height: the height of the patients was measured to the nearest 0.01 m using a portable roll-up meter rule, which consisted of a simple triangular headboard. The participant stood with the head looking straight without wearing any footwear, scarf, or cap. The subject stood against the meter rule while its horizontal bar was put lightly on the upper part subject´s head and the reading was taken.

Body mass index: the Body Mass Index (BMI): BMI (kg/m²) was assessed by dividing the subject´s weight in kilograms by the square of the height in meters. The BMI was categorized as BMI of less than 18.5 kg/m² = underweight; 18.5 - 24.9 kg/m² = normal weight; 25.0 - 29.9 kg/m² = overweight; 30 kg/m² and above = obesity. BMI between 30 and 34.9 kg/m² - obesity grade I; between 35 and 39.9 kg/m² - obesity grade II; over 40 kg/m² - obesity grade III.

Global physical activity questionnaire: the physical activity was assessed by the Global Physical Activity Questionnaire (GPAQ) of WHO STEPs. The total physical activity was presented in MET (metabolic equivalent) minutes per week. The GPAQ was developed by the World Health Organization (WHO) in 2002 as chronic disease risk factor surveillance for physical activity observation. The GPAQ consists of 16 questions designed to estimate an individual´s level of PA in 3 domains (work, transport, and leisure time) and time spent in sedentary behavior. Insufficient physical activity or physical inactivity was defined as engaging in less than 600 minutes of moderate-intensity physical activity per week, or equivalent, as recommended by the World Health Organization (WHO). Sufficient physical activity was moderate and/or vigorous physical activity equivalent to > or = 600 MET minutes/week [11,12].

Alcohol consumption: the alcohol consumption was assessed by referring participants who had consumed alcoholic beverages in the previous 30-day period to be current drinkers; nondrinkers or lifetime abstainers were referred to participants who had never consumed alcohol while past drinkers had previously consumed alcohol but had not done so in the previous 12-month period before the survey [13].

Cigarette smoking: the participants who smoked in the last 30 days were referred to as current smokers; those who had not smoked cigarettes before were considered as non-smokers while those who stopped smoking more than one month before the study were considered as past smokers.

Fruit and vegetable intake: insufficient intake was considered as consumption of fruits and vegetables less than five servings per day [14].

Dietary salt intake: the consumption of salt was evaluated by asking about the frequency of adding salt or salty sauce into the food while preparing or cooking, either before or during eating; and/or the frequency of consuming high-salt processed foods. Participants who frequently (always or often) add salt or salty sauce to food during preparation/cooking, or before or while eating; and/or consumed high-salt processed foods were classified as “at risk”. Frequency of dietary salt intake was categorized as “always” or “often,” “sometimes” and “rare” or “never” [14].

Data collection: data was collected by the researcher and two trained research assistants. This study used a multistage sampling (three stages) and each stage used a different sampling design. In the first stage, six (6) wards were selected from eleven (11) wards in the LGA through a simple random sampling technique. During the second stage: 50% of streets were selected from each selected ward using systematic random sampling. In the third stage, the households in the streets were further selected by using systematic random sampling. The questionnaire was pretested among adults living outside the study area. There was a modification made to the questionnaire from the findings obtained. Data was collected through a face-to-face interview using the trained research assistants who had been trained by the principal investigator.

Data analysis: the data was entered into the computer for analysis using the version 21 software of the Statistical Package for Social Sciences (SPSS 21). Descriptive statistics were done to show the basic features of the study population. The results were presented using frequency tables. Frequency distribution was generated to reveal proportions of the different variables, mean or median with respective standard deviations. Prevalence of hypertension was estimated as a proportion of adults with blood pressure < 140/90 mm/Hg. The chi-square test was used to find out the level of significance of association between categorical variables. The level of significance of this study was set at 5% (p<0.05). Multiple logistic regressions were used and odds ratios with 95% confidence intervals (95% CI) were also calculated to identify associated factors. Adjusted Odds Ratio (AOR) was derived by backward multivariate logistic regression of factors in which p-values were <0.05 which indicates the independent risk factors for hypertension.

Ethical consideration: approval for the study was received from the Ethical Review Committee of the Ministry of Health, Ondo State (reference number of the approval: NHREC/18/08/2016). The study was introduced to prospective subjects (adults 18 years and above) at presentation. The participants were adequately counseled, notified about the study, and with a written informed consent prior to their recruitment. They were informed that participation was voluntary and they could decide to participate or withdraw from the study at any time. Cases of various grades of hypertension and its risk-associated factors were adequately counseled and referred appropriately for expert management according to the national treatment guidelines.

Results     

Of 420 participants in this study, close to half (47.1%) were aged 26 to 44 years category with a mean age of 39.1 ± 13.6 years. The majority of the participants 256 (61.0%) were female while a large proportion (63.8%) among the participants were married. An equal proportion of the participants 128 (30.5%) and 127 (30.20%) were self-employed and government workers respectively; while 20.2% were unemployed. Largely, 83.60% were Yorubas while more than half (59.0%) were university graduates. A large number of the respondents were Christians (91.7%), the majority of the households (64.6%) had less than five members living together and slightly above half of the respondents (56.2%) earned above the national minimum wage of #30,000. Most respondents (64.8%) fell within the middle economic status (Table 1). The overall prevalence of hypertension was therefore 27.9% (95% CI = 23.6% - 32.1%) with stage 1 hypertension at 23.1% (most common) and stage 2 hypertension at 4.8%.

A quarter (20.4%) of the participants were pre-hypertensive, while a small proportion (4.8%) were newly diagnosed during the study (Table 2). Regarding the associated risk factors of hypertension among the participants, close to a quarter (22.7%) were obese (grade 1: 15.5%, grade 2: 6.0, grade 3: 1.2% respectively); 6.2% had smoked cigarettes; and 24.8% had taken alcohol. Medical histories of diabetes and lipids among the participants were 8.8% and 7.4% respectively while 24.5% were as a result of their family history of hypertension. The sufficient servings of fruits and vegetables were 28.1% and 31.0% respectively. Finally, 40.5% of the respondents have never added extra salts to foods right before they ate while slightly above half (52.9%) were adjudged to be physically active (Table 3).

A statistically significant association was established in this study between hypertension and age (p<0.001), gender (p = 0.005), occupation (p<0.001), marital status (p<0.001), educational status (p = 0.025) and monthly income (p = 0.002), family history of hypertension (p = 0.036), personal medical histories of diabetes and lipids (p<0.001), obesity (p = 0.003) and physical activity (p = 0.032). The retirees (83.3%) and widows (67.9%) were more hypertensive among their categories (Table 4). Using multivariate binary logistic regression, the significant predictors identified to be independently associated with the presence of hypertension in the study were age, economic status, marital status, educational level, history of diabetes, and history of lipids.

The elderlies were about four times more likely to be hypertensive than the younger adults (AOR = 3.820, 95%CI = 0.701 - 20.828). Also, respondents who fell within the high and middle economic class were about four (AOR = 3.805, 95%CI = 1169 - 12.385) and three times (AOR = 3.140, 95%CI = 1.421 - 6.938) more likely to develop hypertension respectively. The widows were about four times more likely to be hypertensive than others (AOR = 3.752, 95%CI = 0.749 - 18.783). Looking at the educational level, respondents with primary or no formal education had about twice the likelihood of having hypertension compared to their counterparts with at least a tertiary education (AOR=2.397, 95%CI = 0.937 - 6.589). In the same vein, respondents who had a history of diabetes were ten times more likely to be hypertensive (AOR = 9.602, 95%CI = 3.562 - 25.879). Finally, those with lipids had five times more likelihood (AOR = 5.475, 95%CI = 1.936 - 15.484) (Table 5).

Discussion     

The age range in this study is similar to the study of Zekewos A et al. which showed a median age of 40 years [15]. In contrast, studies by Asemu et al. (18 - 29 years), Kasshun et al. (41 - 60 years), Oladeji et al. (51 years and above), Babatunde et al. (45 - 54 years) and Destaw Damtie et al. (41 to 50 years) had various age groups [16-20]. The age found in this study could be due to the migration of young adults into this community which has the major economic activities in the state. Most of the households were below five, which is similar to the study by Oladeji et al. [18], but in contrast to Zekewos et al. [15]. The small family size recorded in this study could be as a result of the inability of the people to bear the high cost of living since most could be in the middle or lower economic class. The majority in the community were either self-employed or a public servant which is similar to Asemu et al. [16], but in variance to the finding by Rahman et al. [21].

The prevalence of hypertension in this study is similar to the findings of Zekewos et al. Destaw Damtie et al. and Okello et al. [15,20,22]. The proportion of prehypertension in this study was found to be similar to the study done by Adeloye et al. [2]. In contrast, Mirzaei et al. (37.3%), Odili et al. (42.1%) and Babatunde et al. (40.4%) were higher [4,8,19] compare to this current study. The percentage of hypertension and pre-hypertension found in this study could be as a result of the willingness, high level of education, and proximity of the screening tools to the people in the community. This buttressed the need for the provision of affordable, accessible, and available healthcare services close to the community by promoting primary healthcare services. The rate of prehypertension among these people is on the increase; and proper screening and monitoring should be done to avoid it.

The proportion of overweight (22.4%) and obesity (22.7%) is alarming and this could be attributed to a high percentage of physical inactivity (47.1%) among the participants in this study. This value could increase the cardiovascular risk in the community. However, the variations from some studies across the globe could be due to different study areas, population and demographic characteristics [16,22,23]. The medical histories of diabetes and elevated lipids in this study were similar to the study by Dosoo et al. with 10% being diabetic, and with hypercholesterolemia [24]. The proportion of family history of hypertension (24.5%) in this study is notable and could serve as a major risk factor of hypertension. Additionally, self-reported diabetes mellitus, and family history of hypertension are equally similar to the finding in Destaw Damtie in Ethiopia and among Sri Lankan adults [20,25]. Udaya et al. showed that hypertension increases with advancing age (55 years and above) who are likely to be 9 times more likely to develop hypertension as compared to those aged 25-34 years old [23]. In respect to the predictors of hypertension, hypertension is more among prominent among the elderly, retirees, widows, uneducated people, history of hypertension in the family, history of diabetes and lipids, obesity, inactivity, smokers, and those who added extra-salt to food. Previous studies found similar risk factors in the development of hypertension among adults [22,25-27].

Limitations: this study is a community-based cross-sectional study with various significant associations between the variables tested which were not necessarily causal. The research questionnaires used could be prone to self-report bias. Respondents could have over or underestimated their responses. The instruments used have been validated for use in local and international research and this research could serve as a basis for more studies to be carried out by other community researchers in order to buttress and confirm some of the findings above and reduce the limitations of the study.

Conclusion     

The overall prevalence of hypertension and prehypertension is becoming alarming and it can be said that hypertension is becoming a silent epidemic in Akure South local government. Majority of the associated risk factors especially those with history of diabetes, history of elevated lipids, elderlies, family history of hypertension, illiteracy and widows were linked and more at risk to hypertension which can increase morbidity and mortality among the adults living in the community. It is advisable for the government to promote primary healthcare in this community for affordable, available, and accessible healthcare services. Also, people living in this community should be encouraged to use the national health insurance scheme. The proximity of healthcare services to the community especially in developing countries is the key to early diagnosis, prevention, and treatment of hypertension.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Conception and study design: Adewale Oluwafemi Ayadi, Cecilia Bukola Bello, and Abimbola Ayobola Ayadi; data collection: Adewale Oluwafemi Ayadi, Cecilia Bukola Bello, Abimbola Ayobola Ayadi, and Oluyomi Adeyemi; data analysis and interpretation: Adewale Oluwafemi Ayadi, Cecilia Bukola Bello, Abimbola Ayobola Ayadi, Ndidi Okunnuga, Akinola Nelson Adedosu, Oladipo Ogunleye, Dolani Zacharia Gbelela, Ndidi Okunnuga, and Adedeji Ogedengbe; manuscript drafting: Adewale Oluwafemi Ayadi, Cecilia Bukola Bello, Abimbola Ayobola Ayadi, and Ndidi Okunnuga; manuscript revision: Adewale Oluwafemi Ayadi, Cecilia Bukola Bello, Abimbola Ayobola Ayadi, Ndidi Okunnuga, Akinola Nelson Adedosu, Oladipo Ogunleye, Dolani Zacharia Gbelela, Oluyomi Adeyemi, and Adedeji Ogedengbe. All the authors read and approved the final version of this manuscript.

Acknowledgments     

I acknowledge the resident doctors of the Department of Family Medicine, University of Medical Sciences Teaching Hospital, Ondo state (UNIMEDTHC) for the support they gave me while conducting this study. I thank my MPH colleagues, staff and supervisor in the Faculty of Health Sciences, National Open University of Nigeria (NOUN), Akure chapter. I thank my wife, Dr. Ayadi Abimbola, my children (Oluwalonimi, Oluwatofunmi, Diekolayomi), and family and friends who supported me.

Tables     

Table 1: socio-demographic characteristics of adults aged 18 years and above recruited from Akure South local government area, Akure, Ondo state (Nigeria), from December 2022 to February 2023

Table 2: prevalence of hypertension and the categories of blood pressure among adults aged 18 years and above, recruited from the Akure South local government area, Akure, Ondo State (Nigeria), from December 2022 to February 2023

Table 3: associated risk factors related to hypertension among adults aged 18 years and above from the Akure South local government area, Akure, Ondo State (Nigeria), from December 2022 to February 2023

Table 4: association between some risk factors and hypertension among adults aged 18 years and above from the Akure South local government area, Akure, Ondo State (Nigeria), from December 2022 to February 2023

Table 5: multivariate binary logistic regression for the predictors of hypertension in this study from the Akure South local government area, Akure, Ondo state (Nigeria), from December 2022 to February 2023

References