Association between blood pressure, body mass index, and age: A data analytic approach

INTRODUCTION

Blood pressure (BP) develops as a result of the heart pumping blood up against blood vessel walls (arteries). Pumping blood at a higher pressure requires the heart to work harder. High BP is defined as a persistent systolic BP (SBP) or diastolic BP (DBP) of at least 130 mmHg or 90 mmHg, respectively. One’s risk of dying increases along with their risk of acquiring heart, brain, kidney, and other illnesses.^[1] Over nine million people worldwide lose their lives to hypertension each year, according to the World Health Organization (WHO), making it one of the top global causes of disease and mortality.^[2-4] Two-thirds of instances of hypertension are found in low- and middle-income nations, where the disease is more prevalent. This is partly because risk factors have risen in these populations over the past few decades. Body mass index (BMI) is a value derived from the mass and height of a person. The BMI is defined as the body mass divided by the square of the body height and is expressed in units of kg/m², resulting from mass in kilograms and height in meters.^[5] According to the WHO, BMI is divided into three categories: Normal (18.5–25 kg/m²), overweight (26–30 kg/m²), and obese (>30 kg/m²).^[6] BMI is frequently used to gauge an individual’s level of obesity (extra body fat), and studies have shown that it correlates favorably with BP.^[7-9] Disorders such as hypertension, diabetes mellitus, and dyslipidemia, which are risk factors for cardiovascular illnesses, are greatly influenced by excess body fat.^[10] High BMI levels during adolescence have been linked to adult mortality, stroke, and coronary heart disease.^[11,12] High pulse wave velocity, thick carotid intima-media, left ventricular hypertrophy, cardiovascular illness, and adult mortality are also linked to high BP in children and adolescents.^[13-16]

A person’s mass (weight) and height are used to calculate their BMI. The BMI is determined by multiplying a person’s weight (in kilograms) by their height (in square meters).^[3] In an effort to determine if a person is “underweight, normal weight, or obese,” the amount of tissue mass (muscles, fat, and bone) the person possesses is measured.^[4] Determining the trends in BMI-BP connection in teenagers is crucial for formulating a national health policy and forecasting the future burden of cardiovascular illnesses.

According to several types of research,^[17,18] high BP is linked to aging as well as the modernization process. Rapid changes in the economy, epidemiology, and diet have increased the prevalence of overweight and obesity in developing nations.^[19] The WHO claims that since overweight and obesity are now so widespread, they are taking the place of more conventional public health issues like undernourishment and infectious diseases. There are now equal numbers of overfed and underfed persons worldwide.^[20] Although there are several variables that contribute to becoming overweight or obese, one of them is excessive energy consumption, especially when it is combined with a reduction in physical activity.^[21]

One of the factors that affect the occurrence of high BP is aging.^[22] According to a study by Vuvor, the prevalence of high BP increased with age, with the oldest age group (46–50 years old) showing the highest prevalence of high BP.^[3] Age-related increases in the prevalence of hypertension are brought on by deteriorating kidney metabolic processes for salt excretion, hardening of the arteries, and rising obesity.^[23] The general pathophysiological factors that affect the development of hypertension, however, include altered renal and sodium metabolism, altered renin-aldosterone relationships, impaired sodium excretion by the kidney, reset baroreflexes, reset local autoregulation responses, and increased responsiveness to sympathetic nervous system stimuli.^[24,25]

Over time, adjustments have been made to dietary habits, eating patterns, and levels of physical activity as a result of socioeconomic progress. Alterations in diet, body composition, physiological processes, and health are only a few of the effects of these changes. In addition, it contributed to the issue of the rise in cardiovascular diseases and overweight/obesity across age groups. Worrisome is the fact that a limited study has been carried out to investigate the combined influence of age, BMI, and BPs on cardiovascular diseases. Hence, the purpose of the present study was to look into the connection between age, BMI, and BP.

MATERIAL AND METHODS

RESULTS

DISCUSSION

From the oldest age group to the youngest and the middle age group, the rising trend in mean stature was visible. This demonstrates that the middle-aged participants had the highest mean height value. The weakening of intervertebral discs and muscle sag that causes postural alterations may be the cause of the reduction in stature with advancing age. The spine has been known to bow and its height to decrease due to the loss of collagen between spinal vertebrae.^[28] Both Kapoor and Tyagi^[29] and Bhardwaj and Kapoor^[30] have reported similar findings.

With age, body weight grew. The build-up of fat with aging may be the cause of the rise in body weight. Age-related weight gain may be brought on by sedentary lifestyles, loss of muscle mass, and the emergence of potential medical issues. Older persons usually report having lost weight and strength in their final years of life because, in general, aging is typically associated with declines in total and lean mass.^[31-33] In general, muscular mass decreases with age, and even in older people who maintain a steady weight, muscle gradually gives way to fat.^[34] Muscular strength declines as fatty infiltration of the muscle tissue increases.^[33] The typical trend of weight fluctuation over the course of a lifetime is an increase in weight up until the age of 60 or so, followed by a decline.^[35] Increases in both fat and muscle mass are associated with weight growth from early adulthood to midlife.^[36,37] This finding is consistent with those of Kyle et al.,^[38] and Schall^[18] which found no significant positive relationships between BMI and either SBP or DBP or with age. However, it runs counter to earlier research findings that age, BP, and BMI are strongly correlated in Asian populations.^[39,40]

In the black non-Hispanic population, age had a somewhat negative connection with both SBP and DBP and BMI. This demonstrates a reduction in BP and BMI with aging. This observation might be explained by the fact that the study population included people who were being treated for diseases including hypertension and other ailments.

Age had a strong positive correlation with weight and a modest negative correlation with height among Asians. Age and BMI and SBP showed a sluggishly positive connection. Age revealed a marginally negative connection with DBP. SBP and DBP both rose from the youngest to the middle-aged age group and then fell in the oldest age group, demonstrating that BP is not dependent on age. The limited association between age and BMI in this study may be due to the weak link between age and height. Age and high BP are related, according to earlier studies.^[41,42] BMI with SBP and DBP had inverse and inverse correlations, respectively. Both DBP and SBP displayed a slender positive connection with BMI. This pattern is in line with a prior study’s result^[7,43] that non-Hispanic blacks had a positive connection between BMI and both SBP and DBP. Age had a negligible negative link with DBP and a substantial positive correlation with BMI and SBP among non-Hispanic white populations. This demonstrates that whereas BMI and SBP are expected to rise with age, DBP is likely to fall with advancing years. Although not significant, BMI and DBP showed a favorable correlation. This demonstrates that BMI tends to rise with BP. This trend is in line with the findings of Kan et al.,^[44] who found a link between BMI and BP among non-Hispanic blacks and whites. A strong positive association between BMI and BP was discovered in a study done among Delhi-based Punjabi girls.^[45] Similar results in other Indian populations have also been found.^[46,47] BP and BMI are more strongly correlated than race, according to research by Kumanyika et al.,^[48] and this relationship holds true throughout surveys conducted in the United States and among different racial and sex groups. The BMI is one of the most significant predictors of BP, among many other pertinent factors, according to a number of researchers. Although it has long been known that genetics and ethnicity have an impact on the distribution of BP levels within a population, these factors appear to have less of an impact on the variation in BP levels between populations.^[49] BMI, however, was not demonstrated to be a reliable predictor of BP in the current investigation.

According to odds ratios, a high SBP and DBP are significantly predicted by BMI. All three stages of prehypertension, Stage I hypertension, and Stage II hypertension were more likely to occur in obese patients than in persons with normal BMI. Obesity was found to be a significant factor in hypertension in the current investigation.

CONCLUSION

The study found no evidence of an association between BMI and age, SBP, or DBP. In addition, rising age and BP are related. There was a positive and substantial link between BMI, age, SBP and DBP, weight, and height, despite the size of the correlation varying within each population. In comparing various ethnic groups, the study findings suggest that age has different associations with BP, BMI, and other factors. In the black non-Hispanic population, age showed a negative connection with BP and BMI. Among Asians, age had a positive correlation with weight and a negative correlation with height. BP increased from the youngest to the middle-aged group and then decreased in the oldest group, indicating it is not solely dependent on age. BMI showed positive associations with BP across different ethnic groups. Obesity was found to be a significant factor in hypertension. Subjects with greater BMI had higher mean SBP and DBP readings. Obese demographic groups have an increased chance of developing hypertension. Pre-hypertensive and hypertensive individuals were present in significant numbers, particularly in Stage I.