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REVIEW ARTICLE
PREHYPERTENSION: WHAT IS THE CURRENT STATUS?
YC Chia, MBBS (Mal), FRCP (Eng), FAFPM (Hon), University of Malaya, Kuala Lumpur, Malaysia
Address for correspondence: Professor Dr Chia Yook Chin, Department of Primary Care Medicine, Faculty of Medicine
University of Malaya, 50603 Kuala Lumpur, Malaysia. Tel: 603-79492620, HP: 6012-2739366, Fax: 603-79577941. Email: chiayc@um.edu.my
ABSTRACT
Cardiovascular disease (CVD) risk is a continuum across blood pressure. The term prehypertension was introduced because it is now recognized that blood pressure readings between what is deemed optimal and hypertension is associated with increased CVD risk. The prevalence of prehypertension is high and the progression to hypertension is also high. Prehypertension is also commonly associated with other CVD risk factors namely dyslipidaemia, dysgylcaemia and overweight/obesity. Eighty-five percent of prehypertensives have one other or more CVD risk factor compared to normotensives. A recent study has shown a reduction in the development of hypertension from prehypertension with the use of an angiotensin receptor blocker. Unfortunately to date, the impact of treatment of prehypertension on CVD outcome is still unknown except in those with high CVD risk like diabetes or established CVD. However this does not mean nothing can be done for those with prehypertension. The aim of managing prehypertension is to lower the BP, prevent progression to hypertension and to prevent BP related CVD deaths. Lifestyle changes can reduce BP and this by itself can lower CVD risk. Until more evidence about other modalities of treatment become available this is a sensible and cost-effective way to manage prehypertension.
Keywords: Prehypertension, treatment, cardiovascular disease risk, optimal blood pressure, hypertension
Chia YC. Prehypertension: What is the current status? Malaysian Family Physician. 2008;3(2):72-76BACKGROUND
The term “prehypertension” was first introduced when the JNC 71,2 was launched at the American Society of Hypertension annual scientific conference in 2003. It caused tremendous discussions, amongst which were many objections to this new terminology. It was argued that this new definition of “illness” would impact an individual’s employability, his life as well as medical insurance coverage and perhaps even converting what was an otherwise well person into a sick one.
Nevertheless, this term was introduced as part of the categorization of hypertension because it was recognized that there is still an excess cardiovascular disease (CVD) risk at levels of blood pressure (BP) deemed previously to be “normal” or “high-normal”. The rationale for this new term was to bring to the attention of doctors and public health the need for more strenuous efforts at prevention of hypertension.
DEFINITION AND EPIDEMIOLOGY
Prehypertension is defined as systolic BP (SBP) of ≥120-139 mmHg and/or diastolic BP (DBP) ≥ 80-89 mmHg.1,2 This is a change from the definition in JNC-63 for the reasons outlined above. The Malaysian Clinical Practice Guidelines Management of Hypertension 20084 has also adopted this definition. However the 2007 European Society of Hypertension (ESH) and European Society of Cardiology (ESC)5 maintains the previous definitions of optimal, normal and high normal (Table 1).
Table 1. Definition and classification of hypertension| JNC-6 and 2007 | ESH and ESC | definition | JNC-7 and Malaysian | CPG definition | Prevalence in Malaysia,% | |
| Category | Systolic | Diastolic | Definition | |||
| Optimal | <120 | and | <80 | Normal | 32% | |
| Normal | <130 | and | <85 | Pre-hypertension | 120-139/80-89 |
37% |
| High Normal | 130-139 | and/or | 85-89 | |||
| Hypertension | Hypertension | |||||
| Stage 1 | 140-159 | and/or | 90-99 | Stage 1 | 20% | |
| Stage 2 | 160-179 | and/or | 100-109 | Stage 2 | ≥160/100 | 12% |
| Stage 3 | >180 | and/or | >110 |
Whichever definition one adopts there are a few common epidemiological observations namely;
- The prevalence of prehypertension is high. In the US, it is estimated to be around 31%6 and in Malaysia it is around 37%.7,8 This prevalence is even higher than the prevalence of hypertension itself.6,7
- Women are less likely to have prehypertension (23% in women versus 40% in men) This is a surprising finding.6,9
- Prehypertension is associated with overweight/obesity.6,9 With the epidemic of obesity, the prevalence of prehypertension will rise and also reach epidemic proportions.
- Those age 60 and above are less likely to have prehypertension than younger individuals (24% in older versus 34% in younger individuals).6 However this is not because raised BP is not as common in older individuals but because the majority (65%) of older individuals would already have hypertension.
- Prehypertension is commonly associated with other CVD risk factors namely dyslipidemia, dysgylcemia and overweight/obesity. Eighty-five percent of prehypertensives have one other or more CVD risk factor compared to normotensives.9,10
- Prehypertension progresses to hypertension at a high rate of 19% over 4 years.11 One study showed an even higher progression of 40% over 2 years.12
- The rate of progression also depends on the level of BP and age of the individual. Those with “high normal” (BP 130-139/85-89 mm Hg) progresses to hypertension at the rate of 43% over 4 years while those with lower BP (120-129/80-84 mmHg) does so at 20%.11
- BP rises with age and the lifetime risk from age 65 of getting hypertension is nearly 100% over the next 20 years. Hence it is not surprising that those 65 years and older with prehypertension progresses at the rate of 42% versus a lower rate of 27% in the 35-64 age group.11
- In other words, older individuals and those with higher BP levels are at greater risk to progress to hypertension.11
- Prehypertensives have an increased risk of CVD (relative risk RR 1.32; 95% confidence interval 1.05-1.65) compared to normotensives.13
