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| ORIGINAL ARTICLE |
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| Year : 2013 | Volume
: 1
| Issue : 2 | Page : 104-109 |
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Prehypertension and its correlation with cardiovascular risk factors – A study among health sciences students in Malaysia
Mohit Shahi1, Chow Wen Li2
1 Senior Lecturer, Department of Pathology, School of Medicine, Taylor’s University, Subang Jaya, Malaysia
2 Student, Department of Pathology, School of Medicine, Taylor’s University, Subang Jaya, Malaysia
| Date of Web Publication | 21-Aug-2018 |
Correspondence Address:
Mohit Shahi
Senior Lecturer, Department of Pathology, School of Medicine, Taylor’s University, Subang Jaya
Malaysia
 Source of Support: None, Conflict of Interest: None  | 2 |
DOI: 10.4103/2347-6486.239491
Introduction: The levels of blood pressure (BP) are important as it is a potential risk factor that predisposes towards cardiovascular disease (CVD) when the levels are high. After the introduction of the term prehypertension by Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7) (2004), there are heightened interests on the correlation between high-normal levels of BP with CVD risk factors.
Methodology: A questionnaire containing information about eating habits, family history and social habits was given out. Other than that, anthropometric measurements were taken according to the protocol provided by the United States Institutes of Health.
Results: There were a total of 87 respondents that participated in the study. The overall prevalence of prehypertension and hypertension was 40.2% (46.9% - males; 32.7% - females) and 2.3% (male) respectively. Also, it was found that 57.1% of male and 40% of female with increased WC and 75% of male and 33.3% of female with increased WHR have prehypertension. It was also found that subjects with a positive family history of hypertension, diabetes and stroke have a higher tendency towards prehypertension.
Conclusion: There is a high prevalence of prehypertension among males compared to female and that there are positive correlations between the CVD risk factors with prehypertension.
Keywords: Prehypertension, hypertension, risk factors, cardiovascular
How to cite this article:
Shahi M, Li CW. Prehypertension and its correlation with cardiovascular risk factors – A study among health sciences students in Malaysia. J Integr Health Sci 2013;1:104-9 |
How to cite this URL:
Shahi M, Li CW. Prehypertension and its correlation with cardiovascular risk factors – A study among health sciences students in Malaysia. J Integr Health Sci [serial online] 2013 [cited 2023 Jun 9];1:104-9. Available from: https://www.jihs.in/text.asp?2013/1/2/104/239491 |
| Introduction | |  |
People having a systolic blood pressure (SBP) ranging from 120mmHg - 130mmHg and/or diastolic blood pressure (DBP) ranging from 80mmHg - 89mmHg fit into the criteria of prehypertension.[1],[2] As reported by the Seventh Report of the Joint National Committee (JNC7) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, identification of prehypertension would be facilitatory in the prevention of hypertension or slow the rate of progression of BP to hypertensive levels in adolescence through interventions via adoption of healthy lifestyle.[2]
The measurements that are needed to assess the risks involved are body mass index (BMI), waist-hip ratio (WHR) and waist circumference (WC).[3],[4] Also, random blood glucose test is done as an important step in assessing the risk of CVD in a primary health care setting.[5]
The National High Blood Pressure Education Program’s (NHBPEP) Working Group on Hypertension Control in Children and Adolescents had categorised BP between the 90th and 95th percentile in childhood as “prehypertensive” and is an indication for lifestyle modifications.[6] Moreover, prehypertension also predisposes to hypertension.[6],[7] Framingham Heart Study showed that 90% of subjects aged ≥ 55 years had previously been prehypertensive before developing hypertension.[1] This is important as adolescents may have target organ damage when they are diagnosed with prehypertension.[8] Also, prehypertensives have twice the risk of developing hypertension and subsequently CVD, as compared to normotensives.[9]
In the South East Asia region, around 152,000 people die each year from hypertension.[10] Cannon & Vierck stated that “When high BP exists with few or none of the other risk factors, the overall risk is relatively less. But if other risk factors are present the CVD risk increases several folds”.[11] It therefore becomes necessary to acknowledge the role of other risk factors too. These include obesity, cigarette smoking and type2 diabetes with obesity being the most predominant risk factor for CVD among adolescents.
[4],[10],[13],[14]
Recently, various data has shown that essential hypertension can be detected during childhood and adolescent stage and there is a strong link between BMI and BP.[3] The risk of CVD is linked with central obesity (high-risk WC), which can be measured by anthropometric indices such as WC, hip- circumference and WHR.[12],[15] Obesity can also easily be determined through measuring BMI. However, BMI could not accurately assess whether the BMI measured is due to adipose obesity or lean muscle mass as compared to WHR which could be an independent predictor of CVD.[16]
Diabetes, is diagnosed as fasting blood glucose level of ≥ 7.0mmol/L and glucose tolerance level of ≥ 1 l.lmmol/L.[17] A recent survey showed that more than 65% of diabetics do not consider CVD as a severe complication as a consequence of diabetes and only 18% believe that it is indeed a risk factor for CVD.[11]
The prevalence of hypertension amongst the diabetic population is 1.5-3 times greater than that of the non-diabetic population. It was estimated that around 73% of diabetic patients have BP ≥ 130/80mm Hg which is considered as prehypertension based on JNC7 classification of BP .[11]
Risk factors such as smoking, alcohol consumption, obesity, hypertension, a high lipid profile and diet accounts for up to 90% of CVDs worldwide.[18] As compared to normotensives, prehypertensive people are 1.32 times as likely to develop a major cardiovascular event.[7] This correlation is important as results from the Prospective Studies Collaboration (2002) have found that by reducing the SBP by 20mmHg and DBP by 10mmHg would greatly reduce the mortality of CVD by one-half in the middle-aged population.[7],[19]
Smokers and people who drink alcohol often have a higher progression rate towards hypertension from prehypertension.[9] Furthermore the prevalence of diabetics who are prehypertensive is 59.4% as compared to non-diabetic people. High BMI and abnormal WHR were found to have an odds ratio (OR) of 4. and 2.7 in developing prehypertension and hypertension respectively.[20]
| Methods | | |
This study was a cross-sectional survey on the correlation between prehypertension and cardiovascular risk factors carried out in Taylor ' s University Lakeside Campus from 29th June 2012 to 13 th July 2012 among the health science students in Taylor ' s University. A total of 194 sample size was obtained with a 45% response rate.An institutional ethical clearance and informed consent were obtained.
A questionnaire containing items asking about family history, social history such as smoking and drinking alcohol and eating habits were included. The last section was on eating habits with 23 items which was developed by Johnson, Wardle and Griffith .[21]
Furthermore; measurements were obtained from the subjects including BP, random blood glucose, fasting blood glucose, WC, HC, WHR and BMI.
The individuals were classified as normal, prehypertensive and hypertensive based on the classification given by JNC 7.[2] The BMI was measured and subjects were classified as underweight, normal, overweight and obese by using the BMI cut-off point.[22]
Also, the waist and hip circumference was obtained and WHR calculated by using the waist circumference divided by the hip circumference. The WC is measured by placing the measuring tape on top of the iliac crest.[22] The HC was obtained by placing the measuring tape around the widest part of the gluteal region. The cut-off point for classifying the risk they carry based on their WHR calculated is obtained from the WHO report on the WC and WHR.[22] The WC cut-off point was designated into two categories namely increased risk and substantially increased risk. For males, WC of >94cm was considered as increased risk and >104cm as substantially increased risk. For females, WC of >80cm was deemed as increased risk and >88cm as substantially increased risk for developing metabolic disorders.[22]
Furthermore, the random and fasting blood glucose was obtained via finger prick by using the lancet pen and glucometer. The data collected was analysed using the Microsoft Excel. The prevalence of prehypertension was measured and compared with their WHR, waist circumference, BMI status, family history, alcohol intake and diet.
| Result | | |
Out of 195 subjects, 87 responded to the survey with response rate at approximately 45 %. There were 32 males and 55 females. Most of the respondents were of Chinese ethnic group followed by Malay, Indian and others.
The overall prevalence of prehypertension and hypertension is 40.2% and 2.3% respectively. Also, 46.9% of males and 32.7% of female are prehypertensive; 6.25% of males and none of the females were hypertensive.
There is a substantially higher number of prehypertensives among the normal range of BMI compared to the others as shown in [Table 1]. Other than that, it was found that among the 87 subjects there were 2 subjects (normal BMI and overweight respectively) whose blood pressure is classified under hypertension. The prevalence of people under each category is also shown in [Table 1].
Based on the measurement of waist-circumference, 72 subjects were normal whereas a total of 15 subjects were at an increased risk and substantially increased risk.
A total of 9 subjects were prehypertensives with the proportion of female higher than male. Also, only females were found to be under the category of substantially increased risk for CVD as shown in [Figure 1].
As shown in [Figure 2], a small proportion of them have an increased risk of developing disease based on the measurement of WHR. From the data collected, 6 males were found to be prehypertensive and 2 males were hypertensive. Also, for females there were 3 who were classified as prehypertensive.
Most have a family history of high blood pressure followed by diabetes and stroke as compared to the other diseases. From the data, it is also observed that a large proportion of the subjects do not have a positive family history of heart attack followed by stroke and obesity.
Comparison between the associations of family history with blood pressure levels is as shown in [Figure 3] and [Figure 4]. It is seen from [Figure 3] that people with prehypertension tend to have a positive family history of high blood pressure, heart attack and obesity compared to other diseases. Whereas [Figure 5] shows people who do not have a positive family history of those listed showed a steady number of prehypertensives with no inclination towards any family history. {Figure 5}
The mean value for fasting blood glucose and random blood glucose is as shown in [Table 2]. The mean for both males and females were calculated and the mean random blood glucose of male is much higher than female whereas the mean for fasting blood glucose showed that females have a marginally higher mean than males. | Table 2: Glucose measurement and mean of fasting and random blood glucose
Click here to view |
In terms of diet, the effect of diet on those who are prehypertensive is as shown in [Table 3]. It is observed a slightly higher proportion of them have answered yes to questions involving increased fat and sugar intake.
None of the subjects had smoked and 24.1% of them consume alcohol out of which, 38.1% of the subjects are prehypertensive.
| Discussion | | |
The results of this study have indicated that males (46.9%) have a higher prevalence rate of prehypertension than females (32.7%). It also showed that males have a higher tendency to have hypertension compared to females as 6.25% of male were found to have BP levels categorised as hypertension. This is consistent with Cannon & Vierck’s[11] statement that males generally have a higher predisposition towards CVD. However, the results do not agree with those by Ganguly et al[20] which states that the prevalence of females is marginally higher than males. On the other hand, this result is also significant based on Vasan et al’s[23] findings that elevated BP in both genders has an increased predisposition towards a CVD on follow-up.
17.1% of prehypertensive subjects have high BMI as a risk factor. In contrast, 71.4% of subjects under the category of normal BMI are prehypertensive. This does not coincide with Ganguly et al’s[20] report that people with higher BMI have a higher odd’s ratio of developing prehypertension. However, it is said that Asians have a higher percentage of body fat even with low BMI.[22] Therefore, the measurement of WC and WHR is more accurate in predicting CVD risk factors as it gives a more accurate estimate of visceral body. It was found that there are more males under the ‘increased risk’ category whereas only females fall under ‘substantially increased risk’ category which places female under a higher risk in terms of WC measurement. When it is correlated with the state of their BP status, 57.1% of males under the ‘increased risk’ category have prehypertension whereas 40% of females have prehypertension under the same category; all the females who were under the ‘substantially increased risk’ category were classified as prehypertensive. On the other hand, the measurement of WHR and its correlation with BP shows that 75% of males and 33.3% of females who are categorised as having increased risk have prehypertension and 25% of male have hypertension under the same category. This finding would be consistent with the data provided by WHO22 whereby the positive correlation between higher WC and WHR with the end-result of elevated BP is convincing.
Based on the data obtained, those with a positive family history of hypertension had the highest number of prehypertensives followed by diabetes, stroke, obesity and lastly heart attack. This corresponds to the study by Cannon & Vierck[10] that heart disease tends to run in families and that it is positively correlated with increased risk of CVD. Although many that are prehypertensive do not have a family history of aforementioned diseases, it may be due to a background risk that may be due to other risk factors attributed to their rise in BP.
The fasting blood glucose was obtained from 31 subjects whereas random blood glucose was obtained from 56 subjects. The mean value is obtained for both male and female from both categories. Under fasting blood glucose, females have a higher mean value than males with mean values of 4.30mmol/L and 4.29mmol/L respectively. Besides that, the mean value of random blood glucose for male is much higher than that of female with a mean value of 5.21mmol/L and 4.86mmol/L respectively. Since both mean values for each category does not meet the criteria of prediabetes or diabetes, there is no positive correlation found between the levels of blood glucose with prehypertension. Therefore, this finding would be consistent with the finding from Zhang et al[17] that a high proportion of non-diabetics have prehypertension.
Based on the data collected about the diet of the subjects, 42.8% who have increased fat intake and 45.7% of them who have increased sugar intake are prehypertensives. Similarly, 40% and 34.2% who did not have increased fat and sugar intake respectively, have prehypertension. Regarding the intake of vegetable and fibre in their daily diet, 42.8% of them had indeed increased their intake and 51.4% of them who did not are prehypertensive. As increased fat and sugar intake is associated with the development of obesity and diabetes, this finding would indirectly correlate with the statement that diabetes and obesity does play a role in the elevation of BP.[15],[24]
Since none of the subjects who participated in this study smoked, there are no data available to compare with. In contrast, it is found that 24.1% of the subjects do drink alcohol from time to time. Among those who drink alcohol, 38.1% of them are considered as having prehypertension and 61.9% of them are within the optimal BP range. This finding agrees with the finding stated by Cannon & Vierck[11] that drinking alcohol in moderate amount have a protective effect as those in the normal BP range drinks only minimal amount of alcohol infrequently. Although those in the 38.1% who are prehypertensive do not drink much alcohol as well, there may be other factors that are influencing the BP levels at the same time.
| Conclusion | | |
The conclusion drawn from this study is that the prevalence of prehypertension among the students is high with the overall prevalence at 40.2%. This finding is significant as prehypertension is seen as a factor that would increase the predisposition towards hypertension upon reaching adulthood. High BMI is not associated with prehypertension. WHR and positive family history are effective tool to predict a positive correlation with CVD and hypertension. Diet has a great influence blood pressure regulation.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]
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