OBJECTIVETo explore the circadian blood pressure (BP) profile and its influencing factors in essential hypertensive patients after treatment.

METHODSCross-sectional surveillance was carried out in essential hypertensive subjects after treatment whose clinic blood pressure had been under control as 140/90 mm Hg (1 mm Hg = 0.133 kPa) for at least one month. All patients underwent a twenty-four-hour ambulatory blood pressure monitoring device (spacelabs 90207). The nocturnal fall of blood pressure (BP) was calculated from (daytime mean BP-night-time mean BP)/daytime BP, while 'daytime' values were recorded between 6 h and 22 h and 'night-time' values between 22 h and 6 h. Non-dippers were defined as those whose nocturnal decrease in mean systolic BP and/or mean diastolic BP was < 10% of the daytime BP. Binary logistic regression analysis was used to evaluate the correlation between circadian blood pressure profile and factors as gender, age, height, body mass index (BMI), family history of premature cardiovascular disease, women under age 65 or men under age 55, smoking habits, grade of hypertension, and strategy of antihypertensive drugs.

RESULTS208 treated essential hypertensive patients were enrolled in the study. 79 individuals were dippers and 129 were non-dippers. Data from logistic regression analysis showed that four factors as age, premature family history of cardiovascular disease, overweight or obesity, and strategy of antihypertensive drugs were significantly influencing the circadian blood pressure profile in treated hypertensive patients. The incidence of non-dippers in patients of 70 years of age or older and those between 60 and 69 were 3.3 and 2.3 times of those with less than 60 (P = 0.009 and 0.031, respectively). The prevalence of non-dippers in patients with a premature family history of cardiovascular disease was 3.7 times greater than those in subjects without a premature history of cardiovascular disease (P = 0.029). Similarly, the incidence of non-dippers in patients of overweight (24 /= 28) were 3.0 and 4.8 times of those in subjects of normal weight (P = 0.003 and 0.009, respectively). Compared with patients treated with long-acting calcium channel blockers (CCBs), patients treated with angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) alone had less prevalence of nondippers (OR = 0.139, P = 0.010). Patients treated with joint antihypertensive scheme including ACE inhibitors or ARBs(but not including diuretics) had the tendency of lower incidence of abnormal circadian blood pressure rhythm (OR = 0.453, P = 0.118). Patients treated with joint antihypertensive scheme including diuretics (not including ACE inhibitors or ARBs) and with joint antihypertensive strategy including diuretics and ACE inhibitors or ARBs had lower incidence of nondippers (OR = 0.378 and 0.273, respectively; P = 0.030 and 0.011, respectively).

CONCLUSIONSApproximately 2/3 treated essential hypertensive patients had a non-dipper blood pressure profile. Age, premature family history of cardiovascular disease, overweight/obesity, and antihypertensive drugs strategy were correlated with circadian blood pressure profile. Compared with long-acting CCBs, diuretics, ACE inhibitors or ARBs might be helpful in keeping the circadian blood pressure rhythm at normal range.