Hypertension is a major risk factor for stroke and heart disease and is therefore one of the most important preventable causes of premature morbidity and mortality in developed and developing countries.
In the UK, hypertension is the third biggest risk factor for premature death and disability, after smoking and diet. In 2010, 1.4 billion people globally had hypertension which contributes to 18 million cardiovascular deaths annually.
Over a quarter of adults in the UK have hypertension. Prevalence is rising as the population ages. The 2018 UK health survey for England reported a prevalence of 30% in men and 26% in women. The proportion of adults in the population with untreated hypertension decreased from 2003 to 2018 for both men (20% to 13%) and women (16% to 10%).
The population average blood pressure in England has fallen over the last decade by almost 3 mm Hg systolic. The proportion of adults with untreated high blood pressure has reduced from 2003 to 2015 for both sexes (from 20% to 15% among men and from 16% to 10% among women). However, other countries are making much speedier progress. In Canada, 65% of adults with high blood pressure are identified and treated to recommended targets, as opposed to only 35% in England.
Essential hypertension (primary, cause unknown) accounts for the majority of cases, particularly in the older patient.
Secondary hypertension is commonly caused by renal disease, endocrine conditions or pregnancy:
- Renal disease is the most common cause of secondary hypertension. This may be intrinsic renal disease (glomerulonephritis, polyarteritis nodosa, systemic sclerosis, chronic pyelonephritis, or polycystic kidneys) or renovascular disease (atheromatous or fibromuscular dysplasia).
- Endocrine disease:
- Cushing's syndrome
- Conn's syndrome
- Thyroid dysfunction
- Coarctation of the aorta.
- Obstructive sleep apnoea.
- Pre-eclampsia and hypertension in pregnancy.
- Pharmacological substances and toxins - eg, alcohol, cocaine, amfetamines, antidepressants, the combined oral contraceptive (COC) pill, ciclosporin, tacrolimus, erythropoietin, adrenergic medications, decongestants containing ephedrine and herbal remedies containing licorice or ginseng.
Modifiable risk factors include:
- Excess weight.
- Excess dietary salt intake.
- Lack of physical activity.
- Excessive alcohol intake.
Non-modifiable risk factors include:
- Older age.
- Family history.
- Gender (blood pressure tends to be higher in men than in women up to the age of 65 years, whereas the opposite tends to be true over the age of 65 years).
Blood pressure (BP) has a skewed normal distribution within the population and the currently accepted model assumes risk is continuously related to BP. The National Institute for Health and Care Excellence (NICE) recommends the following definitions:
- Stage 1 hypertension - BP in surgery/clinic is ≥140/90 mm Hg and ambulatory blood pressure monitoring (ABPM) or home blood pressure monitoring (HBPM) ranges from 135/85 mm Hg to 149/94 mm Hg.
- Stage 2 hypertension - BP in surgery/clinic is ≥160/100 mm Hg but less than 180/120 mm Hg and ABPM or HBPM is ≥150/95 mm Hg.
- Stage 3 or severe hypertension - systolic BP in surgery/clinic is 180 mm Hg or higher or diastolic BP is 120 mm Hg or higher.
- Masked hypertension - BP in surgery/clinic is less than 140/90 mm Hg but average ABPM or HBPM readings are higher.
- White coat effect - a discrepancy of more than 20/10 mm Hg between clinic and average daytime ABPM or average HBPM blood pressure measurements at the time of diagnosis.
Screening for hypertension
Hypertension is often symptomless, so screening is vital - before damage is done. All adults should have their BP measured, at least every five years up to the age of 80 years, and at least annually thereafter.
Measuring blood pressure
- Use a correctly calibrated and maintained machine (manual or automatic).
- Seated BP is adequate except in elderly patients or those with diabetes who may have orthostatic hypotension (standing BP is needed as well - after at least one minute's standing). If standing systolic blood pressure (SBP) is 20 mm Hg or lower than when seated, review medication, and measure all subsequent blood pressures with the person standing (consider specialist referral if postural hypotension symptoms persist).
- The person should be quiet and relaxed. Remove tight clothing and support the arm with the hand relaxed and the cuff (of appropriate size) at heart level.
- Initially, measure BP in both arms; if there is a persistent difference of >15 mm Hg between arms then ensure subsequent blood pressures are taken in the arm with the higher reading.
Use an automated machine or the following manual method (if the pulse is irregular (eg, in atrial fibrillation), always use the manual method):
- Inflate the cuff whilst palpating the brachial artery, until the pulse disappears. This provides an estimate of systolic pressure.
- Inflate the cuff until 30 mm Hg above systolic pressure, then place a stethoscope over the brachial artery. Deflate the cuff at 2 mm Hg per second.
- Systolic pressure: the appearance of sustained repetitive tapping sounds (Korotkov I). Diastolic pressure: usually the disappearance of sounds (Korotkov V). However, in some individuals (eg, pregnant women) sounds are present until the zero point. In this case the muffling of sounds (Korotkov IV) should be used.
- Record to the nearest 2 mm Hg.
- If initial BP is ≥140/90 mm Hg, take a second or even a third reading and record the two lowest as the clinic BP.
If BP in the GP surgery is between 140/90 mm Hg and 180/120 mm Hg then offer ABPM to confirm the suspected hypertension, or HBPM if ABPM is not available or not tolerated.
- If using ABPM - take ≥2 readings every waking hour, and average at least 14 measurements when deciding whether hypertension is present.
- If using HBPM - on each occasion take two consecutive BP measurements (<1 minute apart), with the person seated. Take readings twice daily (morning and evening) over ≥4 days (ideally 7 days) - disregard the first day and then average the rest.
Diagnosis of hypertension is confirmed if a person has:
A clinic blood pressure of 140/90 mm Hg or higher; and
ABPM daytime average or HBPM average of 135/85 mm Hg or higher.
Those with high normal clinic values (130-139/85-89 mm Hg) subsequently should be checked annually.
While waiting for further BP readings to confirm diagnosis of hypertension, look for target organ damage - look for hypertensive retinopathy, left ventricular hypertrophy on ECG; perform blood tests (serum electrolytes, creatinine, eGFR, fasting glucose and lipids) and urinalysis for albuminuria, proteinuria or haematuria ± albumin:creatinine ratio. Carry out a cardiovascular risk assessment with a suitable assessment tool.
- Hypertensive crisis - there are two types:
- Accelerated (also known as malignant) hypertension: this is a syndrome characterised by severe hypertension (eg, systolic >200 mm Hg, diastolic >130 mm Hg) accompanied by end-organ damage - eg, encephalopathy, dissection, pulmonary oedema, nephropathy, eclampsia, papilloedema and/or angiopathic haemolytic anaemia. Accelerated hypertension needs urgent (same-day) assessment and immediate treatment to reduce the BP within minutes to hours. This is also termed hypertensive emergency.
- Hypertensive urgency: a systolic blood pressure (SBP) ≥180 mm Hg or a diastolic blood pressure (DBP) ≥120 mm Hg without impending end-organ damage. Treatment should safely reduce BP over a few days. Repeat BP measurement within 7 days.
- Suspected phaeochromocytoma: consider this diagnosis if there is labile or postural hypotension, headache, palpitations, pallor and profuse sweating - refer for urgent (same-day) assessment[6, 8].
- Systolic or diastolic pressure: for many years diastolic pressure was considered to be more important than systolic pressure. They are both important determinants of cardiovascular risk.
- Hypertension in the elderly: although age-related rise in systolic pressure can be considered part of the 'normal' ageing process, isolated systolic hypertension (ISH) in the elderly should not be ignored as it is associated with significant morbidity and mortality[8, 9]. Uncertainties remain regarding treatment of hypertension in the elderly; however, NICE guidelines in the UK recommend the same treatment in those aged over 80 years as in those aged 55-80 years, taking into account comorbidity[6, 10].
High BP is usually asymptomatic, except where there is accelerated hypertension.
All patients need a full history and physical examination. Look for a cause (renal, endocrine, etc, as above), particularly in the young, the severely hypertensive and those with resistant hypertension.
- Take a full medication history (non-steroidal anti-inflammatory drugs (NSAIDs), oral contraceptives, steroids, licorice, sympathomimetics, ie cold cures).
- Ask if they are aware of the hypertension. Episodic feelings 'as if about to die' or headaches, or paroxysmal sweats or palpitations, suggest phaeochromocytoma.
- Consider renal causes: whether there is a present, past or family history of renal disease; whether the kidneys are palpable, or there is an abdominal or loin bruit (renovascular disease) or delayed or weak femoral pulses (coarctation).
- Consider whether the patient looks Cushingoid or whether he or she might have Conn's syndrome (tetany, weak muscles, polyuria, hypokalaemia).
- Look for signs of thyroid disease.
- Consider contributory factors: obesity, excess alcohol, salt intakeand lack of exercise, environmental stress, and cardiovascular risk factors (smoking, diabetes, cholesterol and family history) ready for your management plan.
Assess the degree of end-organ damage or complications of hypertension - eg, previous stroke or transient ischaemic attack (TIA), dementia, known left ventricular hypertrophy (LVH)/left ventricular (LV) strain, coronary heart disease (CHD), peripheral arterial disease, or renal impairment. Perform ophthalmoscopy to assess for retinopathy; ideally, dilate the pupils to do so.
- Looking for target-organ damage:
- Urine dipstick test for protein and blood.
- Serum creatinine and electrolytes and eGFR.
- Renal ultrasound scan.
- 12-lead ECG (looking for LVH or signs of CHD).
- Cardiovascular disease prevention:
- Fasting blood glucose.
- Fasting serum total and high-density lipoprotein (HDL) cholesterol.
- Specific investigations for a suspected secondary cause:
- 24-hour urinary metanephrines.
- Urinary free cortisol and/or dexamethasone suppression test.
- Renin/aldosterone levels.
- Plasma calcium.
- Magnetic resonance imaging of the renal arteries.
Referral to a specialist may be necessary for some of these tests where they seem appropriate.
Indications for referral to a specialist
- Urgent treatment is needed: accelerated hypertension, severe hypertension (>220/>120 mm Hg), suspected phaeochromocytoma with severe hypertension, or impending complications (eg, TIA, new-onset confusion, chest pain, signs of heart failure, or acute kidney injury).
- Possible underlying cause: low K+, Na+ elevated (possible Conn's syndrome); elevated creatinine, proteinuria or haematuria; sudden-onset or rapidly worsening or resistant hypertension (ie needs >4 therapeutic agents); young age (consider specialist assessment for those under the age of 40 years).
- Therapeutic problems: unusual BP variability, intolerance to multiple medications or contra-indications, persistent non-adherence or treatment refusal.
- Hypertension in pregnancy.
For a full discussion on cardiovascular disease risk assessment, treatment thresholds and their modification dependent on target organ damage and concurrent diseases, see the separate Hypertension Treatment article. See also the separate articles Hypertension in Pregnancy and Hypertension in Childhood.
Further reading and references
Hypertension; NICE Quality Standards, March 2013
Zhou D, Xi B, Zhao M, et al; Uncontrolled hypertension increases risk of all-cause and cardiovascular disease mortality in US adults: the NHANES III Linked Mortality Study. Sci Rep. 2018 Jun 208(1):9418. doi: 10.1038/s41598-018-27377-2.
Ansah JP, Inn RLH, Ahmad S; An evaluation of the impact of aggressive hypertension, diabetes and smoking cessation management on CVD outcomes at the population level: a dynamic simulation analysis. BMC Public Health. 2019 Aug 1419(1):1105. doi: 10.1186/s12889-019-7429-2.
Egan BM, Kjeldsen SE, Grassi G, et al; The global burden of hypertension exceeds 1.4 billion people: should a systolic blood pressure target below 130 become the universal standard? J Hypertens. 2019 Jun37(6):1148-1153. doi: 10.1097/HJH.0000000000002021.
Kennard L, O'Shaughnessy KM; Treating hypertension in patients with medical comorbidities. BMJ. 2016 Feb 16352:i101. doi: 10.1136/bmj.i101.
Viera AJ, Neutze DM; Diagnosis of secondary hypertension: an age-based approach. Am Fam Physician. 2010 Dec 1582(12):1471-8.
Hypertension in adults: diagnosis and management; NICE (August 2019)
Tackling high blood pressure - from evidence to action; Public Health England (PHE), November 2014
Williams B, Mancia G, Spiering W, et al; 2018 ESC/ESH Guidelines for the management of arterial hypertension: The Task Force for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension: The Task Force for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension. J Hypertens. 2018 Oct36(10):1953-2041. doi: 10.1097/HJH.0000000000001940.
Bavishi C, Goel S, Messerli FH; Isolated Systolic Hypertension: An Update After SPRINT. Am J Med. 2016 Dec129(12):1251-1258. doi: 10.1016/j.amjmed.2016.08.032. Epub 2016 Sep 14.
Tadic M, Cuspidi C, Hering D; Hypertension and cognitive dysfunction in elderly: blood pressure management for this global burden. BMC Cardiovasc Disord. 2016 Nov 316(1):208.
He FJ, Li J, Macgregor GA; Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials. BMJ. 2013 Apr 3346:f1325. doi: 10.1136/bmj.f1325.
Hypertension in pregnancy: diagnosis and management; NICE Guidance (June 2019)