Why is the Chinese hypertension guideline necessary?

The new Chinese hypertension guideline was eventually published.[1] It has been more than seven years since the previous Chinese hypertension guideline was published in 2011.[2] The guideline committee should also be congratulated that this new Chinese hypertension guideline was for the first time published in full length in the English language in this issue of the Journal of Geriatric Cardiology.[3]

This is the fourth Chinese hypertension guideline,[3] after the first, second[4] and third[2] in 1999, 2005 and 2011, respectively. The first Chinese hypertension guideline was printed in a booklet. The document was not so sophisticated, but nevertheless played a role in improving management of hypertension at that time in China. The treatment rate of hypertension increased substantially from 45.5% in 1991[5] to 81.8% in 2002[6] in patients who were aware of the disease (Table 1). The 2005[4] and 2011 [2] Chinese hypertension guidelines were both comprehensive, and dealt with all issues of hypertension including various secondary forms of hypertension and special populations. For the choice of antihypertensive drugs, the guideline recommended five classes of antihypertensive drugs, namely, angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, β-blockers, dihydropyridine calcium-channel blockers (CCBs) and thiazide diuretics.[2]^,[4] Because the dihydropyridine CCBs have been best-evidenced from randomized controlled trials in China,[7]^–[10] and are more efficacious in lowering blood pressure in the Chinese population,[11] this class of drugs was listed in the first place among the recommended drugs.[2]^,[4]

Table 1. Prevalence, awareness, treatment and control rates of hypertension in the recent nationwide blood pressure surveys in China.[5]^,[6]^,[17].

Year of the survey (age)	Number of subjects	Prevalence, %	Awareness, %	Treatment, %	Aware and treated, %	Control, %	Treated and controlled, %
1991 (≥15 yrs)[5]	950,356	11.3	26.6	12.1	45.5	2.8	23.1
2002 (≥ 18 yrs)[6]	141,892	18.8	30.2	24.7	81.8	6.1	25.0
2015 (≥ 18 yrs)[17]	451,755	27.9	46.9	40.7	86.8	15.3	37.6

The new Chinese hypertension guideline was published in a critical time, shortly after the American[12] and European[13] and before the Japanese hypertension guidelines.[14] As we previously explained in a commentary on the 2017 American hypertension guidelines,[15] we did not change the definition of hypertension from the current diagnostic threshold of 140/90 mmHg to 130/80 mmHg of systolic/diastolic blood pressure.[1]^,[3] The committee by and large agrees that blood pressure in the range of 130–139/80–89 mmHg confers significant cardiovascular risk, and should be seriously considered in cardiovascular prevention.[16] However, the current status of blood pressure control in China does not encourage such a change now.

According to the most recent China nationwide hypertension survey in 2012 to 2015, the prevalence of hypertension in 451,755 adults (≥18 years) was 27.9%, and the awareness, treatment and control rates of hypertension were 46.9%, 40.7% and 15.3%, respectively (Table 1).[17] If this survey would be compared with the preceding one in 2002 in 141,892 people of at least 18 years,[6] the prevalence, treatment and control rates of hypertension increased substantially from 18.8%, 24.7% and 6.1%, respectively,[6] and relatively by 48.4%, 64.8% and 150.8%, respectively.[6]^,[17] However, the awareness rate in hypertensive patients and control rate in treated hypertensive patients remained intolerably low, though also with a relative increase of 55.3% and 50.4% from 2002 to 2012, respectively.[6]^,[17] China is fast growing in economy and ageing in population. The prevalence of hypertension is doomed to increase in the next few decades, because of increasing longevity and lifestyle changes. At present, we might have to focus on those with higher blood pressures (≥140/90 mm Hg) and higher cardiovascular risks.

In addition to the huge tasks in controlling hypertension in China, what makes the Chinese hypertension guideline necessary and unique are the characteristics of hypertension in the Chinese population.[18] First, the major risk factors of hypertension are different. Dietary sodium intakes are high in all populations, but extremely high in the Chinese population. In addition, dietary potassium intakes are extremely low in Chinese. In the International Study of Macro/Micro-nutrients and Blood Pressure (INTERMAP), Chinese, compared with American, British, and Japanese populations, had highest dietary sodium intakes and lowest potassium intakes, leading to a 2 to 3 times higher sodium/potassium ratio in Chinese.[19] Second, the pathophysiology of hypertension is different. Probably because of the high dietary sodium intakes, the circadian rhythm of 24-h blood pressure in the Chinese population is characterized of a higher night-time blood pressure. The prevalence of isolated night-time hypertension, defined as a night-time blood pressure of at least 120 mm Hg systolic or 70 mm Hg diastolic and a daytime systolic/diastolic blood pressure less than 135/85 mm Hg, was 82% higher in Chinese than Europeans (10.9% vs. 6.0%).[20]^,[21] Third, the complications of hypertension are also different across ethnicities, being mainly stroke instead of myocardial infarction in Chinese.[22] Fourth, because of the low dietary potassium intakes and high incidence of hypokalemia, and because of the superior stroke protection provided by CCBs than other classes of antihypertensive drugs,[23] CCBs, but not thiazide diuretics, have a high profile in the management of hypertension in Chinese.

To implement the principles and recommendations of the new Chinese hypertension guidelines, a series of strategic actions are being undertaken, with a goal of 50% control rate by 2030.[24] In collaboration with the International Society of Hypertension May Measurement Month project, a blood pressure measurement programme has been running since 2017 every year in May and June.[25]^,[26] Blood pressure was measured in tens of thousands of people who did not measure their blood pressure for more than a year. With this and several other blood pressure measurement actions, it is hoped that the awareness and treatment rates of hypertension will increase to 70% or higher. In the meantime, we are building hypertension excellence centres in regional hospitals throughout China.[24] Hopefully, tens of thousands of hypertension specialists can be nurtured in the next decade. The control rate of hypertension in treated hypertensive patients can then be increased also to 70% or higher.

If a 50% control (<140/90 mmHg systolic/diastolic blood pressure) rate of hypertension would be achieved in the next 10 years, those with a high normal blood pressure or an elevated blood pressure, whatever the term is used for the blood pressure range of 130–139/80–89 mmHg, might require more consideration in the next Chinese hypertension guidelines. Action on this group of people really means earlier and better care.[27]