Octavio J.A.,Institute of Tropical Medicine |
Octavio J.A.,Hospital Of Clinicas Caracas |
Contreras J.,Hospital Of Clinicas Caracas |
Amair P.,Hospital Of Clinicas Caracas |
And 10 more authors.
Journal of Hypertension | Year: 2010
Background: Conventional calculation of mean 24-h ambulatory blood pressure (BP), SBP and DBP based on the average of all BP readings disregards the fact that a larger number of measurements is usually scheduled during the daytime than at night, an imbalance possibly leading to an overestimation of 24-h average BP. The aim of our study was to quantify this possible bias and to explore its determinants. Methods: Four hundred and fifty untreated individuals were subdivided into three groups (150 individuals each) with three different ambulatory blood pressure measurement schedules for day/night: group I, four (day)/two (night) readings/h; group II, four (day)/three (night) readings/h; and group III, with BP readings every 30 min throughout 24 h. Hourly and 24-h averages were computed. The conventional 24-h averages of all SBP and DBP values were compared with the averages of hourly SBP and DBP mean values (time-weighted quantification). The difference between 24-h conventional and 24-h time-weighted BP was computed in each group and related to the degree of nocturnal BP dip and to the ratio between the number of readings of day and night. Result: In the three groups, 24-h conventional and 24-h time-weighted BP values were highly correlated (r > 0.99), 24-h conventional SBP and DBP being significantly higher (P < 0.01) than the corresponding 24-h time-weighted values in groups I and II but not in group III (Bland-Altman analysis). The bias magnitude was related to the day/night ratio in number of readings and to nocturnal BP dip in groups I and II (P < 0.01) but not in group III. Conclusion: The higher number of readings/h during daytime leads to an overestimation of conventional 24-h average BP, particularly in individuals with preserved nocturnal BP dipping. This can be avoided either by scheduling the same number of readings/h throughout 24 h or by performing a time-weighted quantification of 24-h BP. The clinical implications of these different approaches deserve further investigation.© 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.
Parati G.,University of Milan Bicocca |
Parati G.,IRCCS San Luca Hospital |
Schumacher H.,Boehringer Ingelheim |
Bilo G.,IRCCS San Luca Hospital |
Mancia G.,University of Milan Bicocca
Journal of Hypertension | Year: 2010
Objective: The aim of this meta-analysis was to compare the 24-h antihypertensive efficacy of different treatments using the smoothness index. Methods: Data were taken from the telmisartan ambulatory blood pressure monitoring (ABPM) clinical programme. Eleven clinical trials that randomized mild-to-moderate hypertensive patients to treatment with telmisartan 40/80 mg, losartan 50 mg, valsartan 80/160 mg, ramipril 10 mg, amlodipine 5 mg monotherapy, or with an angiotensin receptor blocker (ARB) and hydrochlorothiazide (HCTZ) 12.5/25 mg, were included. Treatment duration ranged from 4 to 14 weeks. The smoothness index was calculated according to the published formula. Results: Altogether, 5188 patients were included (65% men; 52% were using telmisartan as monotherapy or in combination with HCTZ). Telmisartan 80 mg had a higher smoothness index than losartan, valsartan or ramipril (P < 0.05), and was comparable with amlodipine. All combination therapies had a higher smoothness index than monotherapy; the largest value was observed with telmisartan 80 mg and HCTZ 12.5 mg. Overall, the smoothness index was lower in men, older patients, black patients, smokers and in those with lower baseline blood pressure (P < 0.05). Conclusion: The smoothness index was affected by age, race, sex, behavioural and haemodynamic factors. It was also able to differentiate the 24-h blood pressure effects of antihypertensive drugs, with telmisartan and amlodipine achieving the highest values, possibly because of their long plasma half-lives. All combination therapies had a higher smoothness index than monotherapy. An understanding of the relative effects of different antihypertensives on the smoothness index may help to differentiate their effectiveness in reducing blood pressure-related cardiovascular risk. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.