Elsevier

The Lancet

Volume 349, Issue 9050, 15 February 1997, Pages 454-457
The Lancet

Articles
Blood-pressure control in the hypertensive population

https://doi.org/10.1016/S0140-6736(96)07099-7Get rights and content

Summary

Background

In large-scale surveys of individuals with hypertension those whose clinic blood pressure is reduced to 140/ 90 mmHg or less have been found to represent only a small fraction of the hypertensive population. We assessed whether these results arise because of a white-coat effect elevating clinic blood pressure.

Methods

We randomly selected 2400 individuals from the town of Monza, Italy, and invited them to take part in our study. We measured clinic blood pressure as well as home (morning and evening measurements), and 24 h ambulatory blood pressure—ie, blood pressures largely devoid of a white-coat effect. Based on clinic blood pressure participants were then classified as normotensive, untreated hypertensive (clinic blood pressure >140 mm Hg systolic and/ or >90 mm Hg diastolic), or treated hypertensive (having antihypertensive treatment). The mean blood pressures for each group were calculated.

Findings

1651 people took part in the study. The clinic blood pressure of treated hypertensives (n=207; 146·9 [SD 18] mm Hg/ 90·2 [8·6] mm Hg) was only slightly less than in untreated hypertensives (n=402; 148 [15·2] mm Hg/ 93·3 [8] mm Hg) and in both groups the blood pressure values were much greater than those of normotensive individuals (n=1042; 119·5 [10·3] mm Hg/78·1 [6·6] mm Hg) p<0·001. Averaged home and 24 h blood pressures were lower than clinic blood pressures but similarly higher in untreated and treated hypertensive individuals when compared with normotensive individuals. This was also the case for day and night average blood pressures. The number of treated hypertensive patients found to have blood pressures within the normal limits was small not only when based on clinic blood pressure values but also when based on ambulatory blood-pressure values.

Interpretation

In the hypertensive population the number of patients with inadequate blood-pressure control is high not only when assessed in the clinic but also when assessed by ambulatory-blood-pressure monitoring or at home. The high blood-pressure values commonly found in treated hypertensive individuals cannot be accounted for by a white-coat effect but by a true lack of daily-life blood-pressure control.

Introduction

Epidemic logical studies in the USA and Europe show that patients with well-controlled blood pressure represent a small fraction of the hypertensive population.1, 2, 3, 4, 5, 6 Such findings are believed to be due to poor compliance with long-term antihypertensive therapy.1, 7 However, there is the possibility that the blood-pressure measurements used in these studies cause a stress reaction and a pressor response known as the white-coat effect,8, 9 which lead to a distorted view of blood-pressure control.

We tested this hypothesis on a large number of people by measuring clinic blood pressure as well as blood pressures known to be largely free of the white-coat effect10, 11—ie, home and 24 h ambulatory blood pressure.12

Section snippets

Methods

The data reported in this paper come from the Pressioni Arteriose Monitorate E Loro Association (PAMELA) study, which was done to gather information on normal values of ambulatory and home blood pressures. The methodological aspects of the PAMELA study have been reported in detail elsewhere.10 Briefly, 2400 individuals aged 25 to 64 years were selected from the population of Monza, Italy. The sample was chosen to be representative of the Monza residents according to the criteria of the WHO

Results

Of the 1651 of individuals who took part in the study (participation rate 69%) 821 were men and 830 were women. The average age was 46·4 (SD 11·2) years. 1042 participants were classified as normotensive, 402 as untreated hypertensives (96 with only a systolic blood pressure rise), and 207 as treated hypertensives. 19% of the treated group were on diuretics, 30% on β-blockers, 9% on calcium antagonists, 14% on angiotensin-converting-enzyme inhibitors, and 28% on other drugs or drug

Discussion

Our study shows that 28% of the overall sample surveyed in Monza were hypertensive.5 The study also shows that clinic systolic and diastolic blood pressures were raised to similar extents in untreated as in treated hypertensive participants. This finding is consistent with poor blood-pressure control observed in treated hypertensive patients in both American and European populations.1, 2, 3, 4, 5, 6 The important new findings, are that compared with the normotensive population, untreated and

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