In this study, we report the latest prevalence statistics on hypertension among adults in the United States using NHANES. NHANES is a robust data source for studying disease prevalence because it uses a multistage, stratified survey methodology to obtain prevalence data representative of the general, non-institutionalized US population. The data collected via survey instruments included demographic, socioeconomic, dietary, and health related questions. The oversampling of Hispanic persons, non-Hispanic black persons, non-Hispanic Asian persons, and non-Hispanic white and other persons aged 80 years and older were over-sampled ensured enhanced accuracy in determining prevalence rates among underrepresented populations.
Using nationally representative data, we report the prevalence of hypertension in US adult during the years 2013–2018 as 39.5%. Age, sex, racial, and marital status were factors associated with presence of hypertension at 95% CI.
These risk factors have been reported by different studies7–9 in different areas. Studies done on risk factors of hypertension reported that as age increases, the risk of hypertension increases10. Similarly, in this study, the likelihood of hypertension increased with advancing age. As age category increased from 18–44 to 45–54, 55–64, 65–74 and > = 75years, the odds of having hypertension increased from 2.77 [ 95% CI 2.47–3.20], 5.63 [ 95% CI 5.01–6.33], 8.35 [ 95% CI 7.00-9.96], and 13.82 [95% CI 11.56–16.52] respectively. This could be due to the biological effect of increased arterial resistance because of arterial thickening at older age11.
Distinct gender differences in the incidence and severity of hypertension were well-established, and hypertension was more common in men than women12, 13. It is evident that hypertension increase with age in both sexes; however, men have higher blood pressure at a younger age than women14, 15. In our study, the prevalence and the number of hypertension are lower in women than in men until age 45years, but increase later in life. The increasing prevalence of hypertension in older women was often explained by hormonal changes after menopause. Estrogen causes endothelial vasodilation via upregulation of the nitric oxide pathway and inhibition or down regulation of sympathetic and renin angiotensin system activity, as well as endothelin production16, 17. In addition to hormonal changes, anatomical and physiological sex differences may contribute to sex differences in hypertension prevalence in old age18.
Our study supports prior research demonstrating that Black adults have higher hypertension prevalence than White, Hispanic, and other racial adults. Additionally, Black women have the highest prevalence of hypertension, when compared with White, Hispanic, and other racial Americans4. Although differences in diet and lifestyle may contribute to this, socioeconomic factors to accessing healthy food, exercise, and quality healthcare likely increase the burden of hypertension among Black Americans19, 20.
Marital status is also known to play an important role in hypertension6. This study found that married and separated were more likely to develop hypertension than never married, similar to studies in Ghana21. Physiological stress associated with playing important roles in marriage such as caring for children and spouses, increased pressures from making more money and psychological stress from marital discord could negatively impact married subjects health22. Thus these also might bring about a higher odd of hypertension for married people. The stresses associated with a marital breakdown (spousal death, separation or divorce) could precipitate unhealthy lifestyles such as smoking, drinking, less exercise and poor diet and cause unhealthy psychology, e.g., depression. These may, at least partly, explain why those with marital breakdown had a higher risk of hypertension. Allostasis and adaptation are strongly regarded as a determinant of hypertension in literature23.
Strengths of the present study include that the NHANES database comprises a large, nationally representative sample of the US population over many years. Blood pressure was measured using a standardized approach, minimizing bias by taking the average of 3 consecutive readings obtained under the same conditions. Medical histories were collected by trained examiners using established protocols. Prescription medications were also verified with drug containers, helping to eliminate known biases associated with self-report. Our study also has a few limitations. First, our findings are based on survey data and thus we cannot exclude response bias. Second, the cross-sectional design of NHANES precludes the evaluation of downstream clinical outcomes related to uncontrolled BP. Third, we were unable to evaluate differences in the hypertension cascade among Asian American or Hispanic subgroups, such as Filipino or Indian Americans.
The prevalence of hypertension among the adult population in U.S is high, individual's risk of hypertension rises with age. with men having a higher prevalence than women. Women have a lower prevalence and number of hypertension than men until they are 45 years old, but the number increases later in life. Adult blacks have higher hypertension prevalence than whites, Hispanics, and other racial, especially in black females. Separated and married or living with partner are more likely to develop hypertension than never married people. As prevalence of hypertension in the US are rising, with age, sex, marital status, and racial/ethnic minority individuals being disproportionately impacted by hypertension, targeted public health efforts may reduce health disparities and decrease the overall population burden of hypertension.