Prevalence, awareness, treatment, and control of hypertension in Bangladesh: Findings from National Demographic and Health Survey, 2017–2018

Abstract The purpose of this study was to estimate the age‐standardised prevalence, awareness, treatment, and control of hypertension and to identify their risk factors in Bangladeshi adults. Data from 12 904 adults aged 18–95 years, available from the most recent nationally representative 2017–2018 Bangladesh Demographic and Health Survey were used. Hypertension was defined as having systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg, and/or taking anti‐hypertensive drugs to control blood pressure. Age‐standardized prevalence of hypertension and management were estimated with direct standardisation. A multilevel mixed‐effects Poisson regression model with a robust variance was used to identify risk factors associated with hypertension and its awareness, treatment, and control. The overall age‐standardized prevalence of hypertension was 26.2% (95% CI, 25.5‐26.9); (men: 23.5%, women: 28.9%). Among those with hypertension (n = 3531), 36.7% were aware that they had the condition, and only 31.1% received anti‐hypertensive medication. The prevalence of controlled hypertension was 12.7% among those with hypertension and 43.6% among those treated for hypertension (n = 1306). Factors independently associated with hypertension were increasing age, higher body mass index, being women, having diabetes, and residing in selected administrative divisions. A declining trend of hypertension control was observed with increasing age and low education. Hypertension is highly prevalent (one in four) in Bangladeshi adults, while awareness, treatment, and control are low. Irrespective of the risks associated with hypertension and its management, programs to increase its awareness, treatment, and control should be given high priority in reducing hypertension prevalence and improving hypertension control in Bangladesh.


INTRODUCTION
Hypertension is one of the leading preventable causes of premature death and disability. 1 Globally, it accounted for ∼10.4 million deaths and 218 million disability-adjusted life-years in 2017. 2 Hypertension is also a strong predictor of cardiovascular disease (CVD) and stroke. 3 Each 10 mmHg rise in systolic blood pressure is associated with a 25% and 15% increased risk of CVD for women and men, respectively, 4 with similar risks for CVD mortality. 4 The lifetime risk of CVD at age 30 years is 63.3% in people with hypertension compared with 46.1% in people without hypertension. 5 People with hypertension develop CVD on average five years earlier than those without hypertension. 5 Economically, compared to those without hypertension, people with hypertension have substantially higher hospitalisation costs, outpatient care, and prescription medication. 6 In 2019, approximately 1.13 billion people had hypertension globally, 1 compared with 972 million in 2000. 7 Most people with hypertension are from low-and middle-income countries (LMICs) (1.04 billion). 8 Over the past four decades, trends analysis shows a shift in the burden of hypertension from high-income countries (HICs) to LMICs, mostly in South Asia and sub-Saharan Africa. 9 From 2000 to 2010, the prevalence of awareness, treatment, and control increased far more in HICs, than LMICs. 8 This shift is important as hypertension awareness, treatment, and control indicate hypertension management and the associated burden of cardiovascular complications. 10 Bangladesh has experienced a rapid increase in hypertension. 11 A recent meta-analysis of 53 studies found that the overall prevalence of hypertension in Bangladeshi adults was 20%, varying from 1.10% to 75%. 12 The reasons for the variation in prevalence estimates are small sample size, use of data that are not nationally representative, and/or reporting of unstandardised estimates. A nationally representative study included in this meta-analysis reported that the age-standardized prevalence of hypertension was 27.1% in 2011. 13 However, this study was limited to respondents aged 35 years and above; therefore, it cannot reflect the present situation where noncommunicable diseases and their risk factors, including hypertension, are increasingly concentrated in the younger people. 14 Like hypertension, the management of hypertension is also poorly understood due to the small sample size and lack of nationally representative data. 14,15 Hence, understanding the prevalence and factors associated with hypertension and its management is decisive for improving treatment and control in Bangladesh.
To our knowledge, the age-standardized hypertension prevalence, awareness, treatment, control, and factors associated with these,

Study design and sample
Data for this study were extracted from the most recent nationally rep-

Explanatory variables
We identified potential explanatory variables from previously pub-  20 Diabetes was defined as a fasting blood glucose level greater than or equal to 7.0 mmol/L or self-reported use of glucose-lowering medication. 21 Wealth quintile was the household level variable based on household wealth index, which was constructed using principal component analysis from household's durable and non-durable assets (e.g., televisions, bicycles, sources of drinking water, sanitation facilities, and construction materials of houses) 22 and expressed in five categories (poorest to richest).
Community-level factors included were the place of residence (urban vs. rural) and region of residence (administrative divisions).

Statistical analysis
We used descriptive statistics to describe the individual, household, and community-level characteristics of the respondents. The prevalences of hypertension, awareness, treatment, and control were reported as crude and age-standardized estimates. The crude estimates were adjusted using a sampling weight and complex survey design to account for the data structure. We used a multilevel mixed-effects Poisson regression model with a robust variance to identify factors associated with hypertension and its awareness, treatment, and control. The results were presented as a prevalence ratio (PR) with 95% confidence interval (95% CI).
We used Poisson regression because the odds ratio estimated using logistic regression is usually overestimated if the outcome of interest is common, and the study design is cross-sectional. 23    Hypertension is defined as having systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg, or taking any prescribed drugs to control blood pressure. Diabetes is defined as a fasting blood glucose level ≥7.0 mmol/L or self-reported diabetes medication use.

Prevalence of hypertension
The crude and age-standardised prevalence of hypertension by individual, household, and community-level factors are presented in Table 2.

Factors associated with hypertension, awareness, control, and treatment
Three multilevel mixed-effects Poisson regression models were run to identify factors associated with hypertension, awareness, treatment, and control. The results for Model 3 (final model), adjusted for individual, household, and community-level factors, are shown in Table 3.
The results for all other models are shown in Supplementary    Hypertension is defined as having systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg, or taking any prescribed drugs to control blood pressure. Awareness of hypertension was defined as a self-reported previous diagnosis of hypertension by a doctor or nurse in people with confirmed hypertension. Treatment of hypertension was defined as self-reported use of a prescription antihypertensive medication for management of hypertension.
Control of hypertension was defined as receiving antihypertensive medication and having an average systolic blood pressure below 140 mmHg and/or diastolic blood pressure below 90 mmHg. *p value < .05. ***p value < .01. Awareness of hypertension was positively associated with age, sex, BMI, and wealth quintile. People with diabetes were also more likely to be aware (PR 1. Our study showed that the overall age-standardised prevalence of hypertension (26.2%) was higher than the overall age-standardised prevalence of South Asian countries (20.1%), but lower than overall LMICs (31.5%), and HICs (28.5%). 8 The high prevalence of hypertension suggests that Bangladesh contributes significantly to the burden of hypertension in South-East Asia. 25 This is a challenge for the health system of Bangladesh, as the country has moved to the third phase of the epidemiological transition in terms of life expectancy at birth, with a double burden of disease. The rapid increment of hypertension in Bangladesh is most likely due to increasing prevalence and growth in the aging population, 8 urbanization, and Westernized lifestyle, including excess dietary sodium intake and physical inactivity. 8 We found that the prevalence estimates of awareness, treatment, and control of hypertension were low. Our data suggest that Bangladesh has lower awareness and treatment and higher control of hypertension to other LMICs. 8 These findings highlight that although some progress has been made, greater treatment coverage is required, as treating less than one-third of the hypertensive population is insufficient to achieve adequate BP control. The reasons for poor treatment could be explained by the lack of health literacy of hypertension and its consequenceses, care seeking behavior or financial difficulties, and/or no health insurance coverage that need to be considered in future policies and programs. 13 Reasons for poor BP control in those treated for hypertension also need to be considered, including that hypertension occurs comorbidly with other risk factors among older people, which exacerbate each other to make BP control difficult.
Factors associated with hypertension were age, sex, BMI, diabetes, and selected administrative divisions of the country. Women had a higher prevalence of hypertension across all age categories than men, and hypertension awareness was also higher in women, consistent with previous studies in Bangladesh 13,18 and other countries. 26 We confirm obesity was associated with hypertension in this analysis, consistent with global literature. 27,28 Awareness and treatment were also significantly higher in people with obesity compared with normal weight.
There was evidence in our study of more control of hypertension in people with overweight, not obesity, compared with normal weight.
These findings are important, as obesity is increasing in Bangladesh 29 due to the nutritional transition, characterized by the adoption of highenergy Westernized diets, and reduced physical activity. 30 In our study, the level of education and working status were not significantly associated with hypertension in the multivariate analysis, though they were significant in the bivariate analysis. We found that the power of education and employment in explaining hypertension was diminished with the effect of BMI, as over 50% of the sample population who had higher education, were obese. Also, the observation that "education is positively associated with working status" is not true in the Bangladesh context, including our data. Evidence in Bangladesh shows that 37% women are working in paid employment, especially in garment sectors with no or primary education, while many women are highly educated but not engaged in paid employment (involved in unpaid household activities). 31 Thus, the relationship between education and employment in Bangladesh is not linear, further explaining why hypertension was not associated with education or working status.
We also observed that awareness and treatment increased with ageing, whereas control decreased with age, in agreement with the current literature. 26 A possible explanation for the effects of advancing age is that individuals respond to health promotion (awareness) and have the financial resources to seek treatment as they grow older.
However, by then, control is more difficult due to concurrent comorbidities. In addition, poor medication adherence that arises due to the lack of health literacy, poor quality of drugs, or the use of traditional medicines, may also contribute to suboptimal BP control among those who are treated in Bangladesh. 32 Therefore, the educational and awareness-building interventions on the importance of monitoring and controlling BP should be considered in future policies and programmes.
We found that the likelihoods of hypertension awareness and treatment increased with increasing wealth quintiles for which there is inconclusive evidence in the literature 33,34 ; however, we did not find differences in hypertension and its control across wealth quintiles. It may suggest that a similar rising pattern of hypertension in all segments of population is observed regardless of their wealth quintiles; however, people with improved socio-economic status are more likely to be aware of their conditions and received treatment. However, people from higher socio-economic status are more likely to consume more energy, and involved in white-collar jobs and follow sedentary lifestyles, which may increase the risk of high BP. 34 In contrast, several studies, including meta-analyses, suggest a higher prevalence of hypertension in lower socioeconomic groups in HICs due to their higher smoking rates, elevated BMI, and lack of exercise than higher socioeconomic groups. 33,35,36 In line with existing literature, 37 41 These are important as even small reductions in BP may have clinically important effects on hypertension reduction at a population level and future CVD and associated mortality. 42 The policy implications of our findings are that the management of hypertension in Bangladesh will require concerted efforts in primary prevention to raise awareness, including interventions to increase physical activity, achieve a healthy weight, consume diets high in fruits, vegetables, and low in saturated fat. Our results also suggest that more investment, particularly in obesity management, is crucial to achieving better control at a population level. Delaying the onset of complications should be given priority through the aggressive clinical management of both hypertension and diabetes. In addition to interventions in high-risk individuals, more national population targeted approaches are needed in Bangladesh, similar to the national salt reduction programme planned for India, 43 the UK Food Standards Agency Salt Reduction Strategy, 44 and the WHO SHAKE intervention for salt reduction. 45 Finally, barriers to hypertension control within the health care system in Bangladesh need to be addressed at a policy level, such as access to health services, shortage of medicine supplies, long travel distances, long waiting times, and high costs. 46 The strengths of the study are that it used a large, nationally representative dataset suggesting the findings have external validity. A further strength is that clinical variables, including BP and body weight, and height, were measured using high-quality techniques. Our multilevel mixed-effects Poisson regression corrects the overestimation of effects size produced by conventional logistic regression employed in cross-sectional studies, and increased the precision of the findings.
However, this was a cross-sectional study, which limits our ability to infer causal relationships. Further limitations are that we define hypertension and BP control based on BP records at a single time point, and anti-hypertensive medication use was self-reported. Moreover, a significant proportion of people with hypertension were not asked about their treatment status as they were unaware of the condition. Besides, a significant portion of people uses non-prescription medicines to control BP; this data was not collected, therefore, not adjusted for in the analyses. Dietary, physical activity, and smoking data were not collected as such could not be controlled for in the analyses though they are important predictors of hypertension.

CONCLUSION
Hypertension is highly prevalent (one in four) in Bangladeshi adults, while awareness, treatment, and control are low. Therefore, irrespective of the risks associated with hypertension and its management, programs to increase its awareness, treatment, and control should be given high priority in reducing hypertension prevalence and improving hypertension control in Bangladesh.