Hypertension was diagnosed if systolic blood pressure was ≥140 mmHg and/or diastolic blood pressure was ≥90 mmHg when blood pressure was measured once daily for three days respectively without anti-hypertensive medication. Patients with a previous history of hypertension, who have 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; the criteria for hypertension are defined based on clinical and epidemiological data. Normal ideal blood pressure is systolic blood pressure <120 mmHg and diastolic blood pressure <80 mmHg; normal high blood pressure is systolic blood pressure 120-139 mmHg and diastolic blood pressure 80-89 mmHg. between normal blood pressure and elevated blood pressure is defined as normal high value. When the blood pressure level is at normal high, it predicts that the cardiovascular risk will be elevated. Hypertension is further classified into three classes according to the level of elevated blood pressure. Class I hypertension (mild) is 140-159 mmHg systolic and 90-99 mmHg diastolic; Class II hypertension (moderate) is 160-179 mmHg systolic and 100-109 mmHg diastolic; Class III hypertension (severe) is ≥180 mmHg systolic and ≥110 mmHg diastolic. 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.