How much blood pressure is considered hypertension is divided into two cases: unmedicated and medicated, with different criteria for the two cases. In the absence of anti-hypertensive medication, blood pressure was measured once a day for three days, and hypertension was diagnosed if the systolic blood pressure was ≥140 mmHg and/or, diastolic blood pressure was ≥90 mmHg. Patients with a previous history of hypertension, who had received regular blood pressure lowering treatment, were diagnosed with hypertension despite a blood pressure <140/90 mmHg. Blood pressure levels are continuously normally distributed in the population, and there is no clear boundary between normal blood pressure and elevated blood pressure, and the criteria for hypertension are defined based on clinical and epidemiological data. Chinese guidelines for the prevention and treatment of hypertension criteria: Currently, China uses normal blood pressure (systolic blood pressure <120 mmHg and diastolic blood pressure <80 mmHg,, normal high value [systolic blood pressure 120~139 mmHg and (or, diastolic blood pressure 80~89 mmHg] and hypertension [systolic blood pressure ≥140 mmHg and (or, diastolic blood pressure ≥90 mmHg] for blood pressure level classification. The blood pressure levels were defined as normal high values between normal blood pressure and elevated blood pressure. When blood pressure levels were at normal high values, it was predicted that cardiovascular risk would be elevated. Hypertension was further classified into three classes according to the level of elevated blood pressure. Class I hypertension (mild, for systolic blood pressure 140 to 159 mmHg and diastolic blood pressure 90 to 99 mmHg; Class II hypertension (moderate, for systolic blood pressure 160 to 179 mmHg and diastolic blood pressure 100 to 109 mmHg; Class III hypertension (severe, for systolic blood pressure ≥ 180 mmHg and diastolic blood pressure ≥ 110 mmHg. The above criteria apply to men and women over 18 years of age. For children, the 95% median of blood pressure values for different age groups, usually lower than adult levels, was used.