Introduction
This paper focuses on the analysis of annual data of average blood pressure in the United States between 1975 and 2015. The purpose of this analysis is to determine the current trends in blood pressure among males and females, in terms of average systolic and diastolic blood pressure, as well as the prevalence of elevated blood pressure. According to Fisher and Curfman (2018), hypertension is one of the central concerns for healthcare systems around the world, as it affects more than 1 billion people. Raised blood pressure is one of the central contributors to heart disease, stroke, kidney problems, and coronary artery disease (Fisher & Curfman, 2018).
Thus, it is crucial to search for strategies to lower the average blood pressure to prevent hypertension (Rahimi et al., 2021). Therefore, the Centers for Disease Control and Prevention (CDC) (2020) identifies hypertension prevention as one of the primary concerns of U.S. healthcare and has implemented a series of prevention measures to improve the health of the U.S. population. This paper examines the effectiveness of measures implemented by the CDC and the U.S. government in reducing the average blood pressure of U.S. citizens.
Method
This paper employs a quantitative approach to examine trends in the average blood pressure of U.S. citizens, drawing on data from the NCD Risk Factor Collaboration (NCD Risk Factor Collaboration, n.d.). The dataset is comprehensive, containing 18 variables and 82 rows. It provides data points for the age-standardized mean systolic and diastolic pressure, the age-standardized prevalence of high blood pressure, the crude prevalence of high blood pressure, and the number of adults with high blood pressure—all broken down by year and gender. This wealth of information allowed for a thorough trend analysis of both average blood pressure and hypertension prevalence among U.S. adults.
The paper uses age-standardized values, as average blood pressure is highly dependent on age (Fisher & Curfman, 2018). Therefore, it is crucial to mitigate the effect of an aging population on blood pressure statistics to arrive at an unbiased conclusion (White et al., 2018). Two methods of statistical analysis were employed to identify trends in average blood pressure in the U.S.
First, descriptive statistics were used, which included the mean, median, standard deviation, maximum, minimum, skewness, and kurtosis. Second, scatterplots with regression lines were created to identify the trends in the variables against time. The conclusions about the effectiveness of the CDC’s hypertension prevention strategies were drawn from the analysis of these trendlines.
Descriptive Statistics
Descriptive statistics aim to describe two phenomena, including central tendency and variability of data (Hill, n.d.). The purpose of descriptive statistics may be two-fold. On the one hand, descriptive statistics is used to provide a summary of a large set of data in several numbers (Hill, n.d.). On the other hand, descriptive statistics can help identify relationships between multiple variables (Hill, n.d.). Table 1 provides a summary of three variables analyzed in this paper.
Table 1. Descriptive statistics.
The analysis demonstrates that the mean blood pressure of U.S. citizens decreased from 121.34 mmHg to 74.19 mmHg between 1975 and 2015. The standard deviation (SD) for the systolic blood pressure was 4.13, while the SD for the diastolic blood pressure was 2.74. Systolic blood pressure ranged between 116.01 mmHg in women in 1999 and 130.75 mmHg in males in 1975.
The maximum average diastolic pressure of 81.03 was also observed in males in 1975, while the minimum average diastolic pressure was recorded in women in 2004. At the same time, the rate of hypertension ranged between 0.11 and 0.3 with a mean value of 0.18 and an SD of 0.05. The absolute values of skewness and kurtosis for all variables were below 1, indicating that the values were close to the normal distribution curve (McClaive et al., 2018). This implies that the assumption of normality was not violated, which is crucial for regression analysis.
Trend Analysis
Systolic Blood Pressure
The trends are visualized in Figure 1 for males and Figure 2 for females below. Linear regression trendlines are added to the graphs to illustrate the overall trend in changes in systolic blood pressure.
In both graphs provided above, the linear trendline does not provide a good fit for the recent changes in the average systolic blood pressure. In particular, the datapoints show that the trend was clearly downward between 1975 and 2000. However, between 2000 and 2015, the mean systolic blood pressure increased steadily. Therefore, the linear trendline is not an appropriate fit for the dataset, as it does not provide a good fit for the data. However, the polynomial trendline provides a perfect fit for the data. The scatterplots with polynomial trendlines and formulas for systolic blood pressure in men and women are provided in Figures 3 and 4, respectively.
The analysis of the trendline indicates that the systolic blood pressure of both genders has been increasing since the early 2000s. It indicates that the average systolic pressure of U.S. residents is expected to continue increasing in the near future unless significant changes are implemented.
Diastolic Blood Pressure
The trends in diastolic pressure were similar to those in systolic pressure. Since the scatterplots were similar, Figures 5 and 6 below demonstrate the scatterplots with polynomial trendlines.
The analysis shows that trends for diastolic blood pressure generally followed a similar pattern across the population. However, when looking specifically at men, their diastolic blood pressure consistently decreased throughout the entire 41-year period studied. Although the rate of decrease for males slowed down around the early 2000s, the overall downward trend continued, even if the polynomial trendline doesn’t fully capture it. Meanwhile, the trend in women’s diastolic blood pressure resembled the systolic blood pressure trends observed in both men and women. Overall, the age-standardized mean blood pressure for U.S. citizens was falling rapidly between 1975 and the early 2000s.
As indicated by the analysis of gender-specific average blood pressure measurements, the average blood pressure has been increasing slowly between 2005 and 2015. The analysis of blood pressure trends suggests that the CDC’s and the U.S. government’s policies have been ineffective in combating hypertension in recent years. However, it is crucial to analyze the prevalence of high blood pressure among American citizens to draw such conclusions.
Prevalence
The prevalence in American males and females was analyzed using scatter plots and exponential trend lines. The linear trendlines appeared inappropriate for analysis, as they provided a poor fit for the data. Figures 7 and 8 demonstrate the trends in males and females, respectively.
The analysis confirms that the age-standardized percentage of U.S. residents with elevated blood pressure consistently decreased between 1975 and 2015. Although the speed of this reduction slowed over time, the downward trend remained steady for both men and women. This persistent drop suggests that Public health initiatives set by the CDC and the government to combat hypertension were successful during these forty years.
Discussion
Analysis of blood pressure trends in the U.S. has revealed contradictory results. While the average blood pressure showed a slight but consistent increase from the early 2000s to 2015, the prevalence of high blood pressure (hypertension) decreased steadily between 1975 and 2015. One potential explanation for this inconsistency is a decline in the number of people with low blood pressure (hypotension), which would naturally raise the overall average.
A second explanation is the expansion of blood pressure monitoring in the U.S. healthcare system to include a broader, healthier population to prevent hypertension. In contrast, testing was previously limited primarily to those who were already ill (Fisher & Curfman, 2018).
Conclusion
To conclude, analyzing three blood pressure variables in the U.S. from 1975 to 2015 revealed a complex picture. While both average systolic and diastolic pressures consistently dropped until the early 2000s before starting a slight increase, the percentage of the population with high blood pressure steadily decreased over the entire 41-year span. This sustained reduction in hypertension prevalence suggests that the anti-hypertension initiatives set by the CDC and the American government were ultimately successful, despite the conflicting trend in average pressures after 2000.
References
Centers for Disease Control and Prevention. (2020). Prevent High Blood Pressure. Web.
Fisher, N. D., & Curfman, G. (2018). Hypertension—a public health challenge of global proportions. Jama, 320(17), 1757-1759. Web.
Hill, J. (n.d.). Introduction to descriptive statistics. Web.
McClaive, J., Benson, G. & Sincich, D. (2018). Statistics for business and economics. Pearson.
NCD Risk Factor Collaboration. (n.d.). Blood pressure: Evolution of blood pressure over time (United States of America) [dataset]. Web.
Rahimi, K., Bidel, Z., Nazarzadeh, M., Copland, E., Canoy, D., Ramakrishnan, R.,… & Davis, B. R. (2021). Pharmacological blood pressure lowering for primary and secondary prevention of cardiovascular disease across different levels of blood pressure: an individual participant-level data meta-analysis. The Lancet, 397(10285), 1625-1636. Web.
White, M. S., Burns, C., & Conlon, H. A. (2018). The impact of an aging population in the workplace. Workplace Health & Safety, 66(10), 493-498. Web.