Although high BP (hyper-tension) is seen to be one of the most common health risks we face as we get older, the standard method for measuring it is so seriously flawed that many millions of people believe their health is in jeopardy when it isn't, and are willingly taking antihypertensives they don't need, new research is discovering.
Worse, the antihypertensives increase their chances of suffering the heart attack they think the drugs will help them to avoid-and one study suggests that one type of antihypertensive, the calcium-channel blockers, triples the risk.
High BP can be a precursor to heart attack, heart failure, stroke and kidney disease, say doctors, and it is estimated that around one in three adults is hypertensive.
Medicine often describes hypertension as a 'silent killer'. Because there are no symptoms, BP readings are the most common-and frequent-tests performed in medicine, often using a portable device called a 'sphygmomanometer', which includes a cuff that attaches around the patient's arm.
BP levels are determined by two readings: the systolic, which measures the pressure in milli-metres of mercury (mmHg) when the heart beats; and the diastolic, which shows the pressure on the arteries when the heart is at rest. Today, a 'healthy' or 'normal' BP reading is considered to be 120/80 mmHg (the systolic reading is the first number). A raised systolic or diastolic reading-or both-is considered to be a sign of hypertension.
However, the so-called normal or healthy seems to change with the times. Traditionally, doctors used to gauge a healthy systolic BP level as 100 plus the age of the patient, and so an acceptable reading for a 60-year-old would have been 160 mmHg. The goalposts were changed in 2003 to create the current, and more exacting, definition of hypertension. At the same time, the US National Institutes of Health (NIH) also set the 'prehypertensive state'-which can be treated by lifestyle and dietary changes-at anything from 120/80 to 139/89 mmHg. Drug therapy now begins for any reading from 140/90 to 159/99 mmHg. Before 2003, the normal BP was 128/80 mmHg.
However, the current low BP levels are not universally welcomed. As Dr Paul J. Rosch, former clinical professor of medicine at New York Medical College, said: "All that these new guidelines essentially accomplish is to convert 45 million healthy Americans into new patients."
Nevertheless, the new lower threshold was good news for the manufacturers of antihyper-tensive drugs, such as the ACE (angiotensin-converting enz-yme) inhibitors, calcium-channel blockers and diuretic 'water tablets'. Now, more than $26 billion of antihypertensives are prescribed every year throughout the developed world, making it one of the most successful drug groups.
But new research is showing that the majority of these prescriptions is unnecessary. The systolic pressure is the only figure that matters in the over-50s, according to the theory of isolated systolic hypertension (ISH), while the diastolic level is all but irrelevant as we get older, and especially among men.
According to ISH researchers, only a level above 160 mmHg is a cause for concern-20 mmHg above today's 'danger' level. The World Health Organization (WHO) and America's influen-tial Sixth Report of the Joint National Committee on Prevention, Detection, Evalua-tion, and Treatment of High Blood Pressure (JNC VI)-which sets out the 'best practice' recommendations for the diagnosis and treatment of high BP in the US-have fallen in line with the new guidelines. They, too, have set a systolic level of 140 mmHg for the start of drug therapy (J Hum Hypertens, 1998; 12: 621-6), even though the prestigious Framingham Heart Study says there is no evidence to support the start of treatment at such a low reading.
The Framingham researchers estimate that 65 per cent of all hypertension cases in the elderly are caused by raised systolic pressure alone, together with an increase in pulse press-ure (the difference between the systolic and diastolic pressures). However, the researchers note that "evidence incriminating systolic pressure as the dominant BP determinant of cardiovascular disease (CVD) has not been translated into clinical practice" (Drugs Aging, 2003; 20: 277-86).
Researchers from the University of Minneapolis estimate that 100 million Americans-and, by their reckoning, around 20 million Britons-have an 'abnormal' BP reading that poses no threat to either their health or longevity and, yet, makes them candi-dates for a drug.
In uncovering one of medicine's biggest mistakes, the researchers-led by Brent Taylor-studied the health and longevity of 13,792 Americans with different BP levels, and compared those who were given drugs with those who went untreated (J Gen Intern Med, 2011; doi: 10.1007/s11606-011-1660-6).
They discovered a complex picture. There was a stepped, and direct, link between the diastolic level and mortality among the over-50s. As the diastolic pressure increased, so did the risk of death, and especially at readings of more than 90 mmHg-but the risk completely disappeared when the systolic reading was factored in. A normal systolic reading neutralized a diastolic level that was considered life-threatening.
In fact, the researchers found that systolic pressure was a far more important gauge of health risk among the over-50s, whereas the diastolic pressure meant nothing. The reverse was true for the under-50s. This suggests a completely new way of measuring BP that is dependent on age and possibly gender.
The pressure mounts
The importance of the ISH theory has been growing over recent years as researchers discover how accurate a predictor it is, especially among older patients.
Researchers from the University of Leuven in Belgium concluded that doctors mis-judged health dangers-and prescribed antihypertensives inappropriately-when they looked at both the systolic and diastolic levels.
In a meta-analysis of eight studies, the Belgian researchers examined the health records of 15,693 people, who were aged 60 years and older, and who had average BP readings of 160/95.
They found that only the systolic pressure reading was an accurate predictor of fatal and non-fatal heart complications. Every 10-mmHg increase in systolic pressure equated to a near-10-per-cent increase in risk, whereas the diastolic reading provided no helpful indication of future health problems (Lancet, 2000; 355: 865-72).
Researchers in Japan found that systolic pressure alone was an accurate indicator of health problems in both the young and old. A 19-year study, involving 3779 men of all ages, discovered that raised systolic pressure was an independent risk factor for cardiovascular disease, whereas a raised diastolic reading was not significant, irrespective of age. A high systolic pressure increased the risk of CVD by 1.53 times in the 30- to 64-year-olds, by 1.7 times in the 64- to 74-year-olds and by 1.23 in those older than 75 years (J Hypertens, 2006: 24: 459-62).
A French study went further, and even suggested that a "normal" diastolic reading was more dangerous than a high one.
In a review of 77,023 men and 48,480 women-all of whom were healthy at the beginning of the eight-year study-researchers discovered a direct correlation between an increase in systolic readings and heart disease and death. The diastolic measure was irrelevant if the systolic reading was normal. Even a high diastolic reading-normally considered a sign of hypertension-had no bearing on future health, they found.
In fact, a normal diastolic reading was more dangerous in a man with a raised systolic level than was a mild-to-moderate increase in diastolic pressure (J Am Coll Cardiol, 2001; 37: 163-8).
We can't read
A failure to understand the significance of systolic pressure is only part of the problem, as doctors often don't get an accurate reading to begin with. This may be down to several factors-from faulty equip-ment to time of day and the patient's activities prior to the test.
One US study, which tracked the progress of 171 patients in a hospital emergency room, found that the BP readings were wrong in almost every case. Exploring further, the researchers discovered that the automated BP equipment was faulty, and failed to meet even the most basic criteria laid out by the British Hypertension Society (Acad Emerg Med, 2004; 11: 237-43).
In a study of men aged 65 and older, most were victims of 'pseudohypertension', caused by an incorrect or faulty reading. While the BP cuff was reading a level of 180/100, the true level-on average-was just 165/85 mmHg, which some doctors still consider to be normal for the age of the patients (N Engl J Med, 1985; 312: 1548-51).
Even when the equipment isn't faulty, it is still hopelessly inaccurate. Professor William White has described the sphygmomanometer as "medi-cine's crudest investigation".
As he points out, BP can vary as much as 30 mmHg over the course of one day (J Manag Care Pharm, 2007; 13 [suppl S-b]: S34-9). BP can increase with physical exertion, stress of any kind-including the stress of having a blood pressure test, known as 'white-coat hypertension'-the time of day, room temperature, a full bladder, or eating, drinking or smoking within an hour of undergoing the test. Even an animated conversation can raise BP temporarily by as much as 50 per cent.
As mentioned above, the time of day can have a bearing on BP values. People who have their test in the morning are likely to have a far higher level than when the test is carried out in the afternoon.
However, a night-time test is the one that obtains the most accurate reading of all, and some patients are encouraged to wear a blood pressure monitor for 24 hours in order to get an accurate reading. In one study of 7458 people who performed such "ambulatory monitoring" (in the home or out of the hospital), researchers discovered that the night-time readings most accurately predicted health problems (Lancet, 2007; 370: 1219-29).
BP can vary even between arms. The most accurate readings are taken from the left arm, and researchers found a difference of as much as 3 mmHg between the left- and right-arm readings from the same patient (Arch Intern Med, 2007; 167: 388-93). One of the most marked differences noted between the two arms was 20 mmHg, according to one test (JAMA, 1995; 274: 1343).
Bring on the drugs
Whether or not that reading was faulty or just wrong, any 'abnormal' result-and especially any pressure level above 140/90-will almost inevitably trigger a prescription for an antihypertensive drug.
European 'best-practice' guidelines recommend two antihypertensive drugs given at the same time and particularly to patients with a very high BP reading who might be at an increased risk of cardiovascular disease (J Hypertens, 2007; 25: 1105-87).
The three most common two-drug therapies combine a diuretic with either a calcium-channel blocker, a beta-blocker, or an ACE inhibitor or ARB (angiotensin-receptor blocker).
The first of these combination therapies-a diuretic with a calcium-channel blocker-has, in several studies, been proven to be a killer, as it dramatically increases the risk of heart attack. In one of the studies, involving 335 people taking antihypertensive therapy, the combination increased the risk of a heart attack by around 60 per cent with or without a diuretic, and by a similar level when the drug was taken with a beta-blocker (JAMA, 1995; 274: 620-5).
In another, more recent, study, researchers from the University of Washington in Seattle estimated that the risk is far higher: a patient taking a calcium-channel blocker with a diuretic is nearly up to three times more likely to suffer a heart attack, they concluded, after tracking 353 patients (BMJ, 2010; 340: c103).
Beta-blockers are little better. They increase the risk of stroke-although not heart attack-and yet they cannot reduce BP levels, a major review and meta-analysis of studies, including a total of 133,384 patients, discovered (Lancet, 2005; 366: 1545-53). In the UK, the British Hypertension Society was so concerned by these findings that it changed the 'best-practice' guidelines in 2006, removing beta-blockers as a first-line treatment for hypertension, even though these drugs are still regularly used elsewhere in the world.
ACE inhibitors are generally not well tolerated, and can cause a range of side-effects, from hypotension (low blood pressure), heart attack, hepatitis and jaundice to mental confusion, acute kidney failure and impotence.
The ARBs were designed to be safer alternatives, but studies suggest that they are every bit as dangerous as the ACE inhibitors. Valsartan can increase the risk of a heart attack by 19 per cent (Lancet, 2001; 358: 2130-1), while candesartan, another ARB, caused a 36-per-cent increase in heart attacks (Lancet, 2003; 362: 772-6).
And despite spending $26 billion a year on drugs with a dubious safety record-and which may not even work very well-doctors could instead prescribe the old-fashioned diuretics and get the same results-but without the risks.
In a pooled analysis of 42 clinical trials involving a total of 192,478 patients with high BP, low-dose diuretics were as effective at lowering blood pressure as any of the newer agents (JAMA, 2003; 289: 2534-44).
The final analysis
For a condition that affects so many of us, medicine's understanding of hypertension is lamentable.
To summarize, conventional medicine:
u fails to understand the significance of the systolic/ diastolic balance as we age;
u invariably misreads blood pressure levels;
u sets the threshold for hypertension at too low a level;
u does not appreciate that raised BP can be normal part of the ageing process; and
u provides drugs that are dangerous or ineffective, or both.
Despite these shortcomings, the American Heart Association says that hypertension is "easily detected and usually con-trollable", while also admitting that the death rate from hypertension rose 19.5 per cent between 1996 and 2006 in the US, a figure that suggests that the former statement is not true.
Because it has no real answers in its battle with hypertension, medicine is behaving like a policeman in a banana republic: it's too forceful, intrusive, interfering and aggressive.
A more conservative and thoughtful approach might serve them-and us-better.
Factfile: An old problem
Although doctors aren't entirely sure why hypertension happens, most accept that it's primarily caused by diet and lifestyle, in which case, it is known as 'essential hypertension'. Secondary hypertension can be caused by preeclampsia, congenital heart defects, and kidney and adrenal gland problems.
Nevertheless, whatever the cause, raised blood pressure (BP) is most closely associated with growing older. The Framingham Heart Study has fewer than one in 10 participants who are 80 years old or older and have 'normal' BP levels, according to the current thinking. In fact, three-quarters of the participants were hypertensive, and most were developing hypertension (J Hypertens Suppl, 1999; 17: S29-36).
Not surprisingly, perhaps, hypertension has been likened to prostate cancer: for most men, it is an inevitable consequence of ageing, and death is more likely with it than from it. This has been borne out by one study that surprisingly discovered that "although high BP can cause heart disease, it is not present in most people with heart disease" (J Med Screen, 2004; 11: 3-7).
Factfile: Possible causes
Although medicine doesn't know what causes hypertension in 95 per cent of cases, here are a few possible culprits beyond the usual suspects of poor diet, obesity, smoking and lack of exercise.
u Inflammation. Researchers from Harvard Medical School have found high levels of
C-reactive protein, a marker for inflammation, in the blood samples of 5365 women with hypertension (JAMA, 2003; 290: 2945-51).
u Renin. This is an enzyme produced by the body to regulate blood volume. Renin levels are believed to play a part in hypertension-hence the terms 'low-renin hypertension' and 'high-renin hypertension'-although it mainly affects older black people. However, aliskiren, one of the first antihypertensives to reduce renin levels, failed to reduce BP levels in half of patients with hypertension (Am J Hypertens, 2007; 20: 587-97).
u Drugs. Many prescription drugs can cause hypertension. One of the most common are the NSAID (non-steroidal, anti-inflammatory drug) painkillers, which can double the risk of hypertension (JAMA, 1994; 272: 781-6).
Ironically, antihypertensives can also increase BP. In one study of 945 hypertensive patients, 16 per cent saw their BP levels rise even higher while taking one of the four major BP-lowering therapies-namely, diuretics, calcium-channel blockers, beta-blockers and ACE inhibitors (Am J Hyptertens, 2010; 23: 1031-7).
u Stress. The stress of modern life can raise BP, as can an argument or a loud noise. Even the constant sounds of traffic can do it, researchers in Stockholm, Sweden, have found. Around half of the city's residents who suffer from hypertension live within a hundred metres of a busy road. On comparing them with people living in quieter neighbourhoods, the researchers reckoned that traffic noise can increase the risk of hypertension by 150 per cent (Occup Environ Med, 2007; 64: 122-6).
Factfile: A drug-free approach
There are many ways in which you can reduce your high blood pressure without resorting to drugs.
u Supplements. Magnesium levels are closely linked to hypertension and a healthy heart. A deficiency caused hypertension and heart problems (J Exp Med, 1957; 106: 767-76)-at least in male rats-while men who suffered from heart disease were generally ingesting around 12-per-cent less magnesium a day than those who were healthy (Br Heart J, 1988; 59: 201-6). Patients who were given intravenous magnesium soon after a heart attack fared as well as those given conventional treatments (Lancet, 1992; 339: 1553-8).
Vitamin C is also an effective antihypertensive. It was tested against a placebo in a group of hypertensive patients who had similar BP levels. However, after a month, those given 500 mg/day of the vitamin saw a drop in their systolic pressure from an average of 155 to 142 mmHg and a diastolic reduction from 85 to 80 mmHg (Lancet, 1999; 354: 2048-9).
Watermelon extract is another supplement worth considering. In one small preliminary study, a watermelon extract (l-citrulline/l-arginine, 2.7/1.3 g/day) taken every day for six weeks normalized BP levels in a group of nine hypertensive patients (Am J Hypertens, 2011; 24: 40-4).
u Diet. A small piece of dark chocolate every day can reduce a raised BP, especially in the early stages of the problem. In a trial of 44 people, aged between 56 and 73 years, who had early-stage hypertension, half were given 6.3 g of dark chocolate, containing 30 mg of polyphenols, every day for 18 weeks, while the rest had polyphenol-free white chocolate. By the end of the trial, the dark-chocolate group saw their systolic pressure fall by 2.9 mmHg and their diastolic by 1.9 mmHg, while the white-chocolate group reported no changes (JAMA, 2007; 298: 49-60).
Hypertensives who increased their dietary fibre and protein intakes achieved an even more impressive fall in BP. Fruits and vegetables were the main sources of fibre. In all, the 41 participants followed a diet with protein intakes making up 25 per cent of energy and a fibre intake of 27 g every day. At the end of eight weeks, those who followed this diet saw their 24-hour systolic pressure fall by 5.9 mmHg compared with the controls (Hypertension, 2001; 38: 821-6).
Complementing that result, following a low-carbohydrate diet can also have a significant effect. In a study of 146 hypertensive patients, nearly half were able to stop or reduce their antihypertensive medication. In contrast, only 21 per cent of those who were taking a drug, but not following the diet, reported similar reductions (Arch Intern Med, 2010; 170: 136-45).
The DASH (Dietary Approaches to Stop Hypertension) eating plan can be as effective as a drug, one study has found. The diet, which is rich in fruits, vegetables and low-fat dairy foods, achieved an average drop in BP from 146/85 to 134/82 mmHg among the 72 participants who followed it for eight weeks (Hypertension, 2001; 38: 155-8).
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