Blood pressure and age in cross-cultural perspective.

Studies in traditional, nonindustrialized countries have shown that blood pressure need not increase with age in adulthood, although incremental age-related increases in blood pressure throughout adulthood are common in industrialized countries. This observation has influenced a statement by the 1997 Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure that a major future challenge is to "prevent the rise of blood pressure with age." The methods of preventing age-related blood pressure increases are not specified in the report. Anthropological surveys of populations with little or no change in blood pressure with age are difficult to replicate and verify, leaving future researchers the task of developing prevention strategies primarily based on studies of populations in which blood pressure increases with age. Here, I review blood pressure surveys used from 1954 to 1998 that have been used in the literature as examples of blood pressure and age research. This review reveals some of the difficulties in clearly defining the exact relationship between blood pressure and age and some of the problems in the development of methods to prevent age-related blood pressure increases.     

Shift work is not associated with high blood pressure or prevalence of hypertension

Background

Working mostly at night has been suggested to be associated with upset of chronobiological rhythms and high blood pressure, but the evidence from epidemiological studies is weak.

Methods

In a cross-sectional survey, we evaluated the association between shift work and blood pressure, pre-hypertension and hypertension. In total, 493 nurses, nurse technicians and assistants, were selected at random in a large general hospital setting. Hypertension was diagnosed by the mean of four automatic blood pressure readings ≥140/90 mmHg or use of blood pressure lowering agents, and pre-hypertension by systolic blood pressure ≥120–139 or diastolic blood pressure ≥80–89 mmHg. Risk factors for hypertension were evaluated by a standardized questionnaire and anthropometric measurements. The association between the shift of work and blood pressure, pre-hypertension and hypertension was explored using univariate and multivariate analyses that controlled for risk factors for hypertension by covariance analysis and modified Poisson regression.

Results

The mean age of the participants was 34.3±9.4 years and 88.2% were women. Night shift workers were older, more frequently married or divorced, and less educated. The prevalence of hypertension in the whole sample was 16%, and 28% had pre-hypertension. Blood pressure (after adjustment for confounding) was not different in day and night shift workers. The prevalence of hypertension and pre-hypertension by shift work was not different in the univariate analysis and after adjustment for confounding (all risk ratios  = 1.0).

Conclusion

Night shift work did not increase blood pressure and was not associated with hypertension or pre-hypertension in nursing personnel working in a large general hospital.     

Size at birth,maternal nutritional status in pregnancy,and blood pressure at age 17: population based analysis.

OBJECTIVE: To assess the effect of size at birth, maternal nutrition, and body mass index on blood pressure in late adolescence. DESIGN: Population based analysis of birth weight corrected for gestational age, mother''s weight before pregnancy and weight gain in pregnancy, obtained from the Jerusalem perinatal study, and blood pressure and body mass index at age 17, available from military draft records. SETTING: Jerusalem, Israel. SUBJECTS: 10,883 subjects (6684 men and 4199 women) born in Jerusalem during 1974-6 and subsequently drafted to the army. MAIN OUTCOME MEASURES: Systolic and diastolic blood pressures measured at age 17 and their correlation with birth weight, size at birth, mother''s body mass index and weight gain during pregnancy, and height and weight at age 17. RESULTS: Systolic and diastolic blood pressures were significantly and positively correlated with body weight, height, body mass index at age 17, and with mother''s body weight and body mass index before pregnancy, but not with birth weight or mother''s weight gain in pregnancy. CONCLUSION: Variables reflecting poor intrauterine nutrition, including low maternal body mass index before pregnancy, poor maternal weight gain in pregnancy, and being born small for gestational age, were not associated with a higher blood pressure in late adolescence.     

Biological aortic age derived from the arterial pressure waveform

Indexes for arterial stiffness are, by their nature, influenced by the ambient blood pressure due to the curvilinear nature of arterial compliance. We developed a new concept of the "Modelflow aortic age," which is, theoretically, not influenced by the ambient blood pressure and provides an easily understood context (biological vs. chronological age) for measures of arterial stiffness. The purpose of the present study was to validate this pressure-independent index for aortic stiffness in humans. Twelve sedentary elderly (65-77 yr), 11 Masters athletes (65-73 yr), and 12 sedentary young individuals (20-42 yr) were studied. Modelflow aortic ages were comparable with chronological ages in both sedentary groups, indicating that healthy sedentary individuals have age-appropriate aortas. In contrast, Masters athletes showed younger Modelflow aortic ages than their chronological ages. The coefficient of variation of sedentary subjects was three times smaller with the Modelflow aortic age (21%) than with other indexes, such as static systemic arterial stiffness (61%), central pulse wave velocity (61%), or carotid β-stiffness index (58%). The typical error was very small and two times smaller in the Modelflow aortic age (<7%) than in static systemic arterial stiffness (>13%) during cardiac unloading by lower body negative pressure. The Modelflow aortic age can more precisely and reliably estimate aortic stiffening with aging and modifiers, such as life-long exercise training compared with the pressure-dependent index of static systemic arterial stiffness, and provides a physiologically relevant and clinically compelling context for such measurements.     

A comparison of blood pressure measurement over a sleeved arm versus a bare arm

Background

The measurement of blood pressure is a common clinical exam with important health consequences. We sought to determine whether the measurement of blood pressure over a sleeved arm varies from that taken on a bare arm.

Methods

We recruited 376 patients between 18 and 85 years of age from a family medicine clinic between September 2004 and November 2006. They all had their blood pressure recorded using the same automatic oscillometric device, with the cuff placed over their bare arms for the first reading. Each patient was then randomly assigned to either the bare-arm group, for which the second blood pressure reading was also taken on a bare arm, or the sleeved-arm group, for which the second reading was taken with the cuff placed over the patient''s sleeve.

Results

The mean age of the 376 participants was 61.6 years (standard deviation 15.0), 61% of the participants were male, 41% had hypertension and 11.7% had diabetes. We found no clinically important differences between the bare-arm group (n = 180) and the sleeved-arm group (n = 196) in age, sex or body mass index. The mean differences between the first and second readings for patients in the bare-arm group were 4.1 mm Hg (95% confidence interval [CI] 2.8 to 5.5) for systolic blood pressure and 0.1 mm Hg (95% CI –0.7 to 0.9) for diastolic blood pressure. The mean differences between the first and second readings for patients in the sleeved-arm group were 3.4 mm Hg (95% CI 2.1 to 4.7) for systolic blood pressure and 0.4 mm Hg (95% CI –0.4 to 1.3) for diastolic blood pressure. The between-group differences in these values was 0.76 mm Hg (95% CI –1.13 to 2.65) for systolic and –0.31 mm Hg (95% CI –1.48 to 0.86) for diastolic blood pressure; neither of these differences was clinically important or statistically significant.

Interpretation

We found that there was no significant difference in blood pressure recorded over a sleeve or on a bare arm. For practical purposes, the decision to measure blood pressure on a bare arm or over a sleeved arm should be left to the judgment of the health care professional taking the blood pressure.The measurement of blood pressure is one of the most common examinations undertaken in family practice and has important health and management consequences for the patient. Accurate assessment of blood pressure, therefore, is very important. Current guidelines outline standards for obtaining accurate and reproducible blood pressure measurements.¹ These standards include guidelines for the sizes of blood pressure cuffs and the position of the patient''s arm, as well as a recommendation that the patient be seated for 5 minutes before his or her blood pressure is taken. In addition, it has been recommended that blood pressure be measured over the patient''s bare arm.¹ However, the current recommended method to determine blood pressure² has several limitations (e.g., high variability of blood pressure at different times of day or if measured only once, loss of proper technique post-training).Three previous studies have assessed whether blood pressure varies significantly when taken over a sleeved arm compared with a bare arm. Details of the literature review are described in Appendix 1, available online at www.cmaj.ca/cgi/content/full/178/5/585/DC2. In one study, involving 36 patients, Holleman et al³ found no significant differences in systolic or diastolic blood pressure readings taken over the sleeved or bare arm of each patient. However, this study was limited because of its small sample and because blood pressure measurements were taken on both arms simultaneously. A study by Kahan et al,⁴ involving 201 patients, compared blood pressure measurements taken over a sleeved arm, a bare arm and below a rolled-up sleeve. They found that the degree of clothing under the sphygmomanometer cuff did not have a clinically important effect on the reading. Although they found no significant difference in the effect of clothing on blood pressure readings, the study was limited by their design of measuring blood pressure below a rolled-up sleeve. The third study, conducted by Liebl et al,⁵ was published while our study was in progress. Their study, which involved 201 patients, compared blood pressure measurements taken over a sleeved arm and a bare arm with both sphygmomanometric and oscillometric devices. They concluded no significant difference in readings between the sleeved and bare-arm groups. In contrast to previous studies, we sought to determine whether the measurement of blood pressure over a sleeved arm varies from that taken over a bare arm through the use of a control group in which patients'' blood pressure was taken only over a bare arm.     

Comparison of factors affecting daily variation of blood pressure in Filipino-American and Caucasian nurses in Hawaii

Although several studies have examined differences in daily blood pressure variability between African-American and Caucasian groups in the United States, little is known about the blood pressure variation of other ethnic groups. This study examined the effects of emotional state, setting, posture, and ethnicity on the ambulatory blood pressure of female health care workers (nurses and nurse's aides) from 2 ethnic groups: Filipino-Americans (N = 38) and Caucasians (N = 22). Ambulatory blood pressure measurements were obtained at 15-min intervals during a typical work day. Participants reported in a diary their setting (work or home), posture, mood, and specific activity at each measurement. The effects of these factors and ethnicity were examined using analysis of variance (ANOVA). The results show that for all subjects blood pressure was higher at work (P < 0.05), while standing (P < 0.05), during reports of negative moods (anxiety, anger, or sadness) (P < 0.05), and while engaging in activities such as interacting with fellow staff members at work and “washing up” at home. However, the Filipino-American women reported negative moods more frequently than their Caucasian counterparts (P < 0.05), had a greater proportion of readings taken while standing at work, and reacted differently than the Caucasian women to some specific activities; for instance, their blood pressure was not elevated when doing household chores. These results suggest that the extent of blood pressure variation in daily life may depend upon cognitive processes which are influenced by the cultural background and emotional state of the individual. They further suggest that ethnicity has an important impact on blood pressure variation. Am J Phys Anthropol 106:373–383, 1998. © 1998 Wiley-Liss, Inc.     

Three year follow up of patients with raised blood pressure identified at health checks in general practice.

OBJECTIVE--To assess the extent of three year follow up of blood pressure, weight, and smoking habit in patients with raised blood pressure identified at health checks. DESIGN--Retrospective audit of medical and nursing records. SETTING--Three general practices in Oxfordshire. PATIENTS--386 of 448 patients with raised blood pressure (diastolic greater than or equal to 90 or systolic greater than or equal to 160 mm Hg) identified from 2935 patients aged 35-64 attending health checks in 1982-4. MEASUREMENTS and MAIN RESULTS--All records of blood pressure, weight, and smoking habit in the medical record were abstracted for three years after the initial health check. All 42 patients with an initial diastolic blood pressure greater than or equal to 105 mm Hg and 316 of 344 patients with an initial pressure of 90-104 mm Hg had at least one further measurement of their blood pressure. Follow up of smoking habit and of weight was less complete with only half of the 100 smokers and 67 of the 87 obese patients (body mass index greater than or equal to 30) having any documented follow up of these risk factors. Annual follow up in the second and third years occurred in 228/297 (76.8%) and 232/320 (72.5%) in patients with blood pressure greater than 95 mm Hg at the beginning of each year. For patients who smoked annual follow up in these years occurred in fewer than a third and for those who were obese in just over half. On the assumption that those not followed up had not changed, at the end of three years the proportion of patients with diastolic blood pressure greater than or equal to 100 mm Hg had fallen from 61 patients (15.8%) to 31 (8.1%); the proportion of smokers had fallen from 103 (26.7%) to 94 (24.4%); and the proportion of obese patients had fallen from 87 (22.5%) to 79 (20.5%). CONCLUSIONS--These changes were modest and in the absence of a control group cannot be attributed necessarily to health checks. Although the standard of follow up was better than in previously reported studies of the management of hypertension, the results emphasise the need to develop formal protocols for dietary and antismoking interventions and to evaluate formally the effectiveness (and cost effectiveness) of health checks.     

Impact of gonadectomy on blood pressure regulation in ageing male and female rats

Background

Sexual dimorphism in blood pressure has been associated with differential expression of the angiotensin II (AII) receptors and with activity of the nervous system. It is generally accepted that ageing affects kidney function as well as autonomic nervous system and hormonal balance. Given that hypertension is more prevalent in men than women until women reach their seventh decade, we hypothesised that females would be relatively protected from adverse effects of ageing compared to males and that this would be mediated by the protective effect of ovarian steroids.

Methods

Intact and gonadectomised male and female normotensive Wistar rats aged 6, 12 and 18 months were used to study renal function, blood pressure, heart rate, and blood pressure variability.

Results

We observed that intact females had lower levels of proteinuria and higher (12.5%) creatinine clearance compared to intact males and that this difference was abolished by castration but not by ovariectomy. Ovariectomy resulted in a change by 9% in heart rate, resulting in similar cardiovascular parameters to those observed in males or gonadectomised males. Spectral analysis of systolic blood pressure revealed that high-frequency power spectra were significantly elevated in the females vs. males and were reduced by ovariectomy.

Conclusions

Taken altogether, the results show that females are protected from age-related declining renal function and to a lesser extent from rising blood pressure in comparison to males. Whilst ovariectomy had some deleterious effects in females, the strongest effects were associated with gonadectomy in males, suggesting a damaging effect of male hormones.

     

Blood pressure and contraceptive use

In a survey of 461 women routinely attending family planning clinics those taking oral contraceptives had significantly higher mean systolic and diastolic blood pressures than those using non-hormonal contraception. There appeared to be a dose-response relation of blood pressure to the progestogen component of two oral contraceptives with an identical 30 μg ethinyloestradiol component. This supports the idea that the progestogen as well as the oestrogen component has an aetiological role in the rise in blood pressure. There was a significant correlation of blood pressure with duration of current use of oral contraceptive but not with total duration of use. There was also a significant negative correlation of blood pressure with time since oral contraceptives were last taken, and women who had stopped using oral contraceptives over a month previously had similar blood pressures to those who had never taken them. In women taking oral contraceptives those who had either a history of hypertension in pregnancy or a family history of hypertension had significantly higher mean blood pressures than those who did not. Both systolic and diastolic blood pressures correlated independently with weight and body mass index, but controlling for the effect of this and age did not affect the above relations. No significant differences in mean blood pressures were found between different ethnic groups, and there was no relation of blood pressure to reported marital state, social class, parity, smoking, or alcohol use.Any oral contraceptive that has a less adverse effect on blood pressure has implications for general prescribing policy; thus even small differences in the progestogen contents of low-dose oestrogen pills may be important.     

Blood pressure in a national birth cohort at the age of 36 related to social and familial factors,smoking, and body mass.

Blood pressure was measured in a birth cohort of 5362 subjects at the age of 36. The prevalence of hypertension in men (blood pressure greater than 140/90 mm Hg) was almost twice that in women, although women received treatment more often. Deaths of fathers of subjects from hypertensive and ischaemic heart disease were associated with significantly higher mean systolic and diastolic pressures in both sexes. Cigarette smoking was not strongly associated with blood pressure in men and not associated at all in women. Of the social factors, low social class of family of origin was associated with high blood pressure in both sexes; but the strongest association was with current body mass, and birth weight also contributed. Differences in blood pressures between the sexes may have been related to protective biological factors, such as endogenous sex hormones, in women and also to differences in types of employment, smoking habits, and body mass. Differences in blood pressures related to the social class of family of origin may reflect long term influences of class differences on diet, exercise, and educational achievement. The importance of measuring secular trends in obesity and blood pressures is emphasised.     

Reproducibility and the influence of age on interspecimen determinations of blood pressure in the horse

1. The reproducibility of blood pressure determinations on 103 male horses gave an average coefficient of variation of 5.0%. 2. Different parameters affecting the methodology of blood pressure measurements were separately analysed; i.e. size of specimen, size of cuff in relationship to tail circumference and temperature of the environment. 3. A strong positive linear correlation between age and blood pressure in the horse was established for two breeds with widely varying genetic background--Swedish Warmbloods and Arabians.     

Association of sex and age with responses to lower-body negative pressure

Responses of 21 women and 29 men (29-56 yr of age) to -50 Torr lower body negative pressure (LBNP) were examined for differences due to sex or age. Responses to LBNP were normal, including fluid shift from thorax to lower body, increased heart rate and peripheral resistance, and decreased stroke volume, cardiac output, and Heather index of ventricular function. Mean arterial blood pressure did not change. Comparison of responses of the women to responses of an age-matched subset of the men (n = 26) indicated the men had larger relative increases in calf circumference and greater increases in peripheral resistance during LBNP than the women, whereas the women experienced greater increases in thoracic impedance and heart rate. Analyses of responses of the 29 men for age-related differences indicated older subjects had greater increases in peripheral resistance and less heart rate elevation in response to LBNP (P less than 0.05 for all differences, except sex-related heart rate difference, where P less than 0.10). Based on these data and the data of other investigators, we hypothesize the age-related circulatory differences in response to LBNP are due to a reduction in vagal response and a switch to predominant sympathetic nervous system influence in older men. We cannot exclude the possibility that diminished responsiveness in the afferent arm of the baroreceptor reflex also plays a role in the attenuated heart rate response of older men to LBNP.     

The pressure tolerance of deep sea amphipods collected at their ambient high pressure

• 1.1. Deep sea benthic amphipods were collected at their normal ambient pressure of 394–442 atm from depths of approximately 4000 m (Parulicella caperesca, Orchomene sp. and other species).
• 2.2. Their activity at their normal pressure and temperature was observed and the responses to a standard pressure test were noted.
• 3.3. Contrary to a prediction derived from the responses of similar animals from lesser depths, the 4000 m amphipods did not convulse at high pressure although they exhibited mild hyperexcitability above 400 atm followed by a progressive inhibition of activity starting at approximately 700 atm.
• 4.4. In failing to convulse at high pressure the amphipods from 4000 m differ radically in their pressure tolerance from those which live at depths down to 2700 m.

     

Retrograde coronary venous perfusion at low pressure

The effectiveness of localized retrograde coronary venous perfusion (RCVP) in preventing or reversing myocardial ischemia after acute ligation of a coronary artery is described. Ten domestic pigs (Group I) underwent aorto left anterior coronary vein grafting with RCVP at systemic pressure. In another set of ten pigs (Group II), the coronary vein was similarly grafted, but the proximal end of the graft was perfused with oxygenated blood by means of an external pump at reduced pressure and flow. In both groups, RCVP successfully reversed the mechanical or electrical effects produced by 2 to 5 minutes of acute arterial ligation. After several hours, Group I animals showed evidence of acute ischemia and developing infarction. Group II animals, however, were maintained for 7 hours or more with regional RCVP and no evidence of ischemia. Retrograde coronary venous perfusion at reduced pressure may be more effective than perfusion at systemic pressure in providing myocardial blood flow.     

Baroreflex sensitivity during operant blood pressure conditioning

Baroreflex sensitivity was measured in baboons operantly conditioned to increase their diastolic blood pressure in daily, 12-hr sessions, by using the extent of increases in interpulse interval per unit of increase in systolic pressure after intravenous phenylephrine injection as an index of baroreflex sensitivity. Following training, baroreflex sensitivity increases averaging 32% were observed before and after the 12-hr conditioning sessions. During the conditioning sessions, however, consistent diastolic blood pressure elevations averaging 17% (14 mmHg) were accompanied by significant decreases in baroreflex sensitivity averaging 44% relative to the increased before and after sensitivity levels. The results suggest that changes in baroreflex sensitivity participate in operantly conditioned blood pressure changes.     

Effects of an angiotensin-converting enzyme inhibitor (captopril) on blood pressure in anephric subjects.

Randomised, double-blind cross-over trials were performed in seven anephric patients to determine the effect of the orally active angiotensin-converting enzyme inhibitor captopril on blood pressure in fluid-depleted and fluid-replete patients. Patients were given captopril, 100 mg orally, or placebo one hour after haemodialysis, when they were fluid depleted. Their mean (+/- SEM) supine blood pressure fell from 127 +/- 12/71 +/- 6 mm Hg before captopril to 106 +/- 13/54 +/- 4 mm Hg 24 hours after the drug, while on placebo it rose from 123 +/- 11/73 +/- 5 mm Hg to 134 +/- 10/82 +/- 8 mm Hg. All patients developed orthostatic hypotension after captopril. In the fluid-replete state, two days after haemodialysis, captopril had no effect on blood pressure. The plasma concentration of active renin was extremely low and did not rise after fluid withdrawal or captopril. Thus the hypotensive effect of captopril did not appear to depend on circulating renin concentrations. The concept of "renin-dependent" hypertension, which is responsive to captopril, as opposed to "volume-dependent" hypertension, which is not responsive to captopril, may therefore be invalid.     

Home blood pressure monitoring with nurse-led telephone support among patients with hypertension and a history of stroke: a community-based randomized controlled trial

Background:

Adequate control of blood pressure reduces the risk of recurrent stroke. We conducted a randomized controlled study to determine whether home blood pressure monitoring with nurse-led telephone support would reduce blood pressure in patients with hypertension and a history of stroke.

Methods:

We recruited 381 participants (mean age 72 years) from outpatient and inpatient stroke clinics between Mar. 1, 2007, and Aug. 31, 2009. Nearly half (45%, 170) of the participants had some disability due to stroke. Participants were visited at home for a baseline assessment and randomly allocated to home blood pressure monitoring (n = 187) or usual care (n = 194). Those in the intervention group were given a monitor, brief training and telephone support. Participants who had home blood pressure readings consistently over target (target < 130/80 mm Hg) were advised to consult their family physician. The main outcome measure was a fall in systolic blood pressure after 12 months, measured by an independent researcher unaware of group allocation.

Results:

Despite more patients in the intervention group than in the control group having changes to antihypertensive treatment during the trial period (60.1% [98/163] v. 47.6% [78/164], p = 0.02), the fall in systolic blood pressure from baseline did not differ significantly between the groups (adjusted mean difference 0.3 mm Hg, 95% confidence interval –3.6 to 4.2 mm Hg). Subgroup analysis showed significant interaction with disability due to stroke (p = 0.03 at 6 months) and baseline blood pressure (p = 0.03 at 12 months).

Interpretation:

Overall, home monitoring did not improve blood pressure control in patients with hypertension and a history of stroke. It was associated with a fall in systolic pressure in patients who had uncontrolled blood pressure at baseline and those without disability due to stroke. Trial registration: ClinicalTrials.gov registration {"type":"clinical-trial","attrs":{"text":"NCT00514800","term_id":"NCT00514800"}}NCT00514800Worldwide about 15 million people have a stroke each year.¹ Adequate control of blood pressure reduces the risk of recurrent stroke by up to 40%.² However, about 1 in 3 adults have blood pressure readings above recommended targets.³ Systematic reviews suggest that home monitoring is associated with reduced blood pressure^4–7 and may improve compliance with treatment and encourage lifestyle changes.⁸ But the benefits tend to be modest.^4,5 Co-interventions, such as patient education and support from health professionals, are important and may lead to intensification of antihypertensive treatment.^8,9Despite the importance of good control of blood pressure in patients with a history of stroke, little is known about home monitoring in this group. Physical and cognitive impairments resulting from stroke may adversely affect patients’ compliance and ability to use the equipment successfully. We conducted a randomized controlled trial to determine whether home blood pressure monitoring with nurse-led telephone support was associated with reduced systolic blood pressure after 12 months in patients with hypertension and a history of stroke. Because PROGRESS (the Perindopril Protection Against Recurrent Stroke Study)² showed that antihypertensive medications reduced the risk of recurrent stroke among patients with or without hypertension who had a history of stroke, we aimed to assess home monitoring in unselected patients with hypertension and a history of stroke across the blood pressure range.     

Geographic distributions of within-population variability in blood pressure

Data on mean blood pressure with standard deviation were extracted from the medical and anthropologic literature for as many populations as possible. The populations were classified as traditional, transitional, or modern. Both mean and within-population variability were found to be higher in more modern populations, confirming the prediction that variability of a character of low heritability is higher in an adverse environment, where it is more difficult to maintain homeostasis. In addition, variability increases with age, indicating a breakdown in homeostasis with aging. On average, males had higher diastolic blood pressure than females, and on average, females had greater variability in systolic blood pressure than males. There was a highly significant negative relationship between latitude and within-population variability in blood pressure.     

The BpTRU automatic blood pressure monitor compared to 24 hour ambulatory blood pressure monitoring in the assessment of blood pressure in patients with hypertension

Background

Increasing evidence suggests that ABPM more closely predicts target organ damage than does clinic measurement. Future guidelines may suggest ABPM as routine in the diagnosis and monitoring of hypertension. This would create difficulties as this test is expensive and often difficult to obtain. The purpose of this study is to determine the degree to which the BpTRU automatic blood pressure monitor predicts results on 24 hour ambulatory blood pressure monitoring (ABPM).

Methods

A quantitative analysis comparing blood pressure measured by the BpTRU device with the mean daytime blood pressure on 24 hour ABPM. The study was conducted by the Centre for Studies in Primary Care, Queen's University, Kingston, Ontario, Canada on adult primary care patients who are enrolled in two randomized controlled trials on hypertension. The main outcomes were the mean of the blood pressures measured at the three most recent office visits, the initial measurement on the BpTRU-100, the mean of the five measurements on the BpTRU monitor, and the daytime average on 24 hour ABPM.

Results

The group mean of the three charted clinic measured blood pressures (150.8 (SD10.26) / 82.9 (SD 8.44)) was not statistically different from the group mean of the initial reading on BpTRU (150.0 (SD21.33) / 83.3 (SD12.00)). The group mean of the average of five BpTRU readings (140.0 (SD17.71) / 79.8 (SD 10.46)) was not statistically different from the 24 hour daytime mean on ABPM (141.5 (SD 13.25) / 79.7 (SD 7.79)). Within patients, BpTRU average correlated significantly better with daytime ambulatory pressure than did clinic averages (BpTRU r = 0.571, clinic r = 0.145). Based on assessment of sensitivity and specificity at different cut-points, it is suggested that the initial treatment target using the BpTRU be set at <135/85 mmHG, but achievement of target should be confirmed using 24 hour ABPM.

Conclusion

The BpTRU average better predicts ABPM than does the average of the blood pressures recorded on the patient chart from the three most recent visits. The BpTRU automatic clinic blood pressure monitor should be used as an adjunct to ABPM to effectively diagnose and monitor hypertension.     

Alcohol and blood pressure: the INTERSALT study.

OBJECTIVES--To assess the relation between alcohol intake and blood pressure in men and women and in men at younger and older ages; to examine the influence of amount and pattern of alcohol consumption, as well as of acute effects, taking into account body mass index, smoking, and urinary sodium and potassium excretion. DESIGN--Subjects reported alcohol consumption for each of seven days before standardised blood pressure measurement, and whether they had consumed any alcohol in the 24 hours before measurement. SETTING--50 centres worldwide. SUBJECTS--4844 men and 4837 women aged 20-59. MAIN OUTCOME MEASURES--Effect of alcohol on blood pressure estimated by taking a weighted average of regression coefficients from centres. Acute effect assessed by examining mean differences in blood pressure of non-drinkers and of heavy drinkers who had and had not consumed alcohol in the 24 hours before measurement. Effect of pattern of consumption assessed by examining mean differences in blood pressure of non-drinkers compared with drinkers (i) whose intake was concentrated in fewer days or who were drinking more frequently, and (ii) whose alcohol intake varied little over the seven days or varied more substantially, as indicated by the standard deviation of daily consumption. RESULTS--Of the 48 centres in which some people reported consuming at least 300 ml/week of alcohol, 35 had positive regression coefficients linking heavy alcohol consumption to blood pressure. Overall, alcohol consumption was associated with blood pressure, significantly at the highest intake. After account was taken of key confounders, men who drank 300-499 ml alcohol/week had systolic/diastolic blood pressure on average 2.7/1.6 mmHg higher than non-drinkers, and men who drank > or = 500 ml alcohol/week had pressures of 4.6/3.0 mmHg higher. For women, heavy drinkers (> or = 300 ml/week) had blood pressures higher by 3.9/3.1 mmHg than non-drinkers. Heavy drinking and blood pressure were strongly associated in both sexes, and in men at both younger (20-39 years) and older (40-59 years) ages. In men who were heavy drinkers, episodic drinkers (those with great variation in daily alcohol consumption) had greater differences in blood pressure compared with non-drinkers than did regular drinkers of relatively constant amounts. CONCLUSION--The significant relation of heavy drinking (3-4 or more drinks/day) to blood pressure, observed in both men and women, and in younger and older men, was independent of and added to the effect on blood pressure of body mass index and urinary excretion of sodium and potassium. The findings indicate the usefulness of targeting those at high risk as well as the general population to reduce the adverse effects of alcohol on blood pressure.