This is the first study to examine the changes in prevalence of hypertension and its risk factors among the adults in Bangladesh. A separate analysis was performed for two groups, 18–34 years as young adults and 35 years and above as older adults, using two waves (i. e. 2011 and 2018) of nationally representative survey data. The major findings are as follows: 1) in general, the prevalence of age-specific hypertension has increased and there is no subgroup in which it has decreased; 2) the prevalence has become almost double in some geographic locations, e.g. Chittagong, Sylhet; 3) among each wealth index category, there has been over 50% significant increase in the prevalence of hypertension ; 4) regression models reveals that age and BMI were the independent risk factors of hypertension; 5) the adjusted effects of working status and wealth index are no longer significant in predicting the hypertension status in 2018; 6) trends are more favorable in women than in men, and in unmarried adults than in married adults; and 7) as expected, there are no differences in hypertension among younger adults (18–34 years) by sex, marital status, place of residence, and working status in 2018.
Our study in line with previous studies identified that hypertension prevalence among adults in Bangladesh is increasing steadily.[13, 15–18] Comparing 2011 and 2018 data sets, it is evident that hypertension prevalence is increasing in almost all subgroups of adults in Bangladesh. From 2011 to 2018, the overall prevalence of hypertension among young adults aged 35 years or older significantly increased from 25.84–39.40%. The prevalence reached nearly double in 2018 among three of the seven geographic regions compared to 2011. The largest relative increase in prevalence of hypertension is in Chittagong and Sylhet followed by Barisal, Rajshahi, and Rangpur. Moreover, geographic location was found as a significant factor of hypertension even after controlling for other factors in the logistic regression models.
The prevalence of hypertension was high among females in both survey years; however, the relative increase among men was significantly higher (75%) than women (39%) from 2011 to 2018. Our findings of significant positive associations between adult hypertension status and established risk factors, such as age and BMI, are similar to other studies.[12, 13, 26, 27] The odds of having hypertension among overweight and obese adults are 94% and 126% higher than normal-weight adults, respectively in 2018 and these results are also consistent with studies in Bangladesh and in other developing countries.[12, 18, 27, 28] The prevalence of hypertension increased by more than 50% among non-diabetic individuals in Bangladesh. Diabetic status was significantly associated with hypertension in both the 2011 and 2018 surveys.
Higher education and higher socio-economic status were significantly associated with hypertension only in 2011. The adjusted odds ratio for the richest individuals dropped from 1.84 in 2011 to 1.11 in 2018. The adjusted odds of having hypertension were not significantly different among adults having no education, primary education, and secondary education in 2011. However, the reverse situation is prevalent in 2018. Individuals having secondary education have higher odds of having hypertension than individuals with no education. The likelihoods of having hypertension among the poorest, poorer and middle-income groups were not found significant in both periods. However, richer, and richest adults had 37% and 84% more odds of having hypertension than the poorest adults in 2011.
Another unique aspect of this study in Bangladesh is the identification of contributing factors associated with hypertension among younger adults (18–34 years). Hypertension prevalence in this age group was 12.75% with a slightly higher prevalence in urban adults than rural adults. Like older adults (≥ 35 years), age, overweight and obesity and being diabetic are significant risk factors for hypertension among young adults. Younger adults’ greater likelihood of having hypertension being living in other than Dhaka regions, particularly in Rangpur and Chittagong, are plausibly associated with their lower access to the socioeconomic development opportunities, poverty and geographical remoteness. The risk of hypertension among adults aged 25–29 and 30–34 years are 1.5 and 2.28 times, respectively than adults aged 18–24 years. Interestingly, the odds of having hypertension is 1.5 times higher [AOR: 1.50, 95% CI: 1.15, 1.94] among diabetic younger adults. Hypertension prevalence among active age population is a concern considering its economic and health burden in Bangladesh. [30–33].
In the subgroup analysis by sex, we found that education level was not significantly associated with the hypertension among women in 2011 and 2018. This is expected as men and women have equal opportunities for access to education over the last two-three decades. Overtime, the likelihood of having hypertension among obese females have increased more than five times compared to normal-weight female after adjusting other covariates. To better understand the relationship between obesity and hypertension among Bangladeshi women further studies are required. Marital status among men was found insignificant in 2011 though, the odds of having hypertension is 52% lower among married men in 2018 and, the situation is reversed among female overtime.
In the subgroup analysis by place of residence (i.e. urban vs rural), the odds of hypertension between male and female were significantly different in rural areas in 2011 whereas this difference is only significant among urban areas in 2018. Urban females had 1.64 times higher odds of having hypertension than urban males in 2011 whereas sex is not a significant factor for hypertension among urban adults in 2018. In contrast, there was no significant difference in having hypertension among rural male and female in 2011 while female in rural areas have 1.54 times higher likelihood of hypertension than male in rural areas in 2018.This may be related to the socio-economic development in rural areas where people are getting facilities like urban areas.
Strengths and limitations
One of the greatest strengths of this study is the use of large sample which represents adults 18 years and older population in Bangladesh. To our knowledge, this study for the first time estimated the national hypertension prevalence and its risk factors among general adults of Bangladesh. The second important strength is that we compared changes in estimates of hypertension predictors between 2011 and 2018 surveys along with subgroups analyses: such as 18–34 years, by sex, and by place of residence. Thirdly, we considered complex survey data analysis methodology in our study which produces variance estimation accounting for post-stratification adjustments to the sampling weights. However, some of the important factors such as physical activity, dietary behavior, drinking habits are not included as those variables are not collected by BDHS. Moreover, considering the nature of the cross-sectional survey design, we are unable to comment on the causal relationships between the outcome and the predictors.
Despite these limitations, this large-scale population-based study may help us to conclude that almost 4 in 10 adults (35 + years) have high blood pressure and the relative increment in prevalence over time is alarming among men (74%) than women (39%). Age and overweight/obesity are the two most important risk factors of hypertension for all adult population irrespective of sex, residence, educational attainment, and wealth index. The risk of hypertension varies from one geographic location to other, with higher risks in Rangpur and Barisal division and relatively lower risk in Chittagong division as compared to Dhaka division suggested the importance of further study to examine higher increase overtime in these regions. Rapid increase in obesity, less physical activity, unplanned urbanization may be the driving forces for the extensive burden of hypertension in Bangladesh. In light of our study findings and increasing rates of mobile phone users, social media campaign and mobile phone text message may be directed for informing young and middle-age adults about the importance of healthy lifestyle and physical activity to avoid the saddle of hypertension and other non-communicable diseases.