Linda Brookes, MSc

Medscape Cardiology.  2007; ©2007 Medscape

 

Hypertension may be a largely asymptomatic condition -- but the consequences are far from insignificant. New data report that hypertension is the largest cause of the absenteeism that, in addition to "presenteeism," costs US businesses as much as $30 billion per year -- with clear implications for what businesses should be doing to address this problem. Another report documents hypertension as the single greatest cause of long-term healthcare in Europe. A third report finds that hypertension, in all its forms, is on the increase again in young people and adolescents (after years of decline), concomitant with the "epidemic" of obesity, while another US study, after discussion of the guideline definition of adolescent hypertension, reports that hypertension is underdiagnosed in this population. Finally in this month's Highlights, a new study carefully dissects the relative contributions of daytime vs nighttime blood pressure readings for predicting future events.

New Report Documents Economic Impact of Hypertension in the United States

A report published in October by the American Hospital Association shows the number of work days lost or that are unproductive due to chronic health conditions such as hypertension, diabetes, and asthma have significant effects on the national and local economies.^[1] On average, about 164 million work days are lost annually due to these 3 chronic conditions, at a cost of $30 billion to employers, researchers report.

In 2006, for every 1000 working Americans aged 18-64 years, an estimated 1221 work days were lost due to asthma, diabetes, or hypertension. Asthma accounted for most of the time lost, at 927 days per 1000 working Americans. Hypertension and diabetes accounted for, respectively, 181 days and 112 days lost per 1000 workers. Thus in 2006, for every 1000 US workers, 4.5 weeks of work were lost due to an episode of hypertension.

Workplace absenteeism due to these conditions varied widely by region and by state. Hypertension accounted for 200 days missed per 1000 employees in the Southeast but fewer than 160 days missed in the North and Southwest. At the extremes of lost-work hours due to hypertension were:

The report also highlights productivity lost due to "presenteeism" (ie, when people are at work, but are not fully functioning because of illness or other medical conditions). Presenteeism can cut individual productivity by one third or more and, according to the report, health-related costs due to presenteeism can be higher than those related to absenteeism. The average annual cost of presenteeism per employee with hypertension is estimated to be $247. However, the report acknowledges that presenteeism is difficult to measure.

The report says that employers increasingly recognize that they have an important role to play in promoting health and productivity. More than 100 of the 1000 largest employers in the United States currently offer on-site care, including clinics with occupational healthcare, primary care, and pharmacy services, and this number is forecast to increase to at least 250 of the top 1000 by the end of 2007. The report cites a number of examples of health promotion programs, which 90% of all US employers with ≥ 50 employees claim to have initiated and that can result in significant decreases in blood pressure and cholesterol among participating employees.

The report also points to the cost savings that can result from such programs, citing a survey that found an average savings of $5.93 for every $1 spent, as well as an average reduction in sick leave absenteeism of 28% and health costs of 26%.^[2] Employers also believe that offering health insurance contributes to better employee health and helps reduce absenteeism. In addition, workers who are entitled to paid sick leave take fewer sick days and are less likely to come to work sick and thus are more likely to be productive at work.

Comment

Commenting on the report, Rich Umbdenstock, president and chief executive office of the American Hospital Association said, "Millions of Americans are unnecessarily suffering from chronic conditions. One thing this study demonstrates is the need to keep people feeling better -- able to go on with their lives and work. We can manage chronic conditions. The message is clear, preventive medicine and wellness programs must be central to our health care system."

Hypertension: The Most Common Reason for Long-Term Medical Treatment in Europe

According to a new report published by the European Commission, one fourth of the population of the European Union (EU) is undergoing long-term medical treatment, and the most common reason for this is hypertension. These findings are included in Health in the European Union, the latest publication in the public health program of the European Commission's Health Strategy 2003-2007.^[3] The data in the report are based on a survey commissioned by the European Commission's Health and Consumer Protection Directorate General and carried out during September-October 2006 in the 25 states that were members of the EU at that time, as well as the 2 countries that joined in January 2007 (Bulgaria and Romania) and Croatia, which is still negotiating to become an EU member. The survey found that among respondents who reported receiving long-term treatment, over one third (36%) said that hypertension was part of, or the sole, reason for their need for medications.

The prevalence of hypertension varied considerably by country. Countries in East Central Europe, particularly Bulgaria, Romania, and Slovakia, and the Mediterranean area (particularly Greece) reported the highest proportion (≥ 50%) of people under long-term treatment for hypertension, whereas in Belgium, the Netherlands, and Luxembourg (Benelux), hypertension was mentioned by ≤ 25%.

The survey underlined the increased prevalence of hypertension with age, affecting just 2% of long-term treatment recipients aged 15 to 24 years, compared with 45% of the 55+ age group. The occupational group most at risk of hypertension was "house persons" (homemakers), with 38% of these undergoing long-term antihypertensive treatment; an even higher proportion of retired respondents (44%) mentioned long-term therapy for hypertension. Another major difference was education level, with more (42%) of all those ending their education at age 15 years receiving long-term treatment for hypertension, compared with 32% of those who ended their education at age ≥ 20 years.

On a positive note, almost 60% of EU citizens said they had their blood pressure measured in the year preceding the survey. This figure included 20% who did it on their own initiative, 32% who did it at the initiative of a doctor, and 7% who had their blood pressure measured as part of a screening program. The authors of the report were encouraged to note that this represented an increase of almost 10% over the figure (50%) reported in 2003.^[4] The increase primarily represented more tests carried out on physicians' own initiative (up 5% from 27% in 2003), supplemented by a slight increase in testing initiated by patients (up 3% from 17%). The highest testing rates were seen in Luxembourg, where 80% of the population had a blood pressure test, followed by Estonia (72%) and Portugal (71%). The lowest rates occurred in Ireland, although even here almost half of those surveyed (46%) had been tested.

Different national initiatives appeared to account for some of the increases in blood pressure testing. In France there was a strong drive by French doctors to get their patients tested, with 55% of French respondents in the survey saying they had been tested on this basis alone. On the other hand, in countries such as Malta, the initiative appeared to come more from patients themselves, with 40% of those surveyed saying they had been tested on their own initiative. Few data were available on screening programs, but there was evidence that these accounted for tests among a significant portion of respondents in Slovakia (20%) and Sweden (18%).

Blood pressure tests were markedly more common among the oldest segment of the population. Of respondents aged ≥ 55 years, almost 8 of every 10 (79%) had a test over the year before interview, over twice the proportion of respondents aged between 15 and 24 years (36%). More women than men had their blood pressure measured annually (62% vs 55%), most often suggested by their doctors (35% vs 28%). People who were unemployed and the self-employed were less likely to be tested annually (both 48%, compared to 58% of managers). Demographic analysis of annual blood pressure testing reflected the responses about blood pressure testing in general.

The report emphasizes the importance of lifestyle measures in lowering blood pressure, including making dietary changes and exercising; 12% of the total survey respondents said they had recently changed their way of life to lower their blood pressure. Among people who said that hypertension was the reason for their long-term treatment, half (48% of men and 50% of women) said they had recently made lifestyle changes with the aim of lowering their blood pressure.

After hypertension, the survey found that the next most common reasons for long-term treatment in the EU were muscle, bone, and joint problems (24%), diabetes (15%), and chronic anxiety and depression (10%). Despite all these responses, and the finding that about 3 in every 10 Europeans (29%) have a long-standing illness or health problem, 73% of people reported that they were in "good" or "very good" health. The survey also showed that about 4 of every 10 EU citizens (38%) had a cholesterol test in the 12 months preceding the survey, an increase from 29% in 2003, and that 13% of survey respondents had made lifestyle changes to reduce their cholesterol levels.

Prevalence of Hypertension Increasing Along With Obesity in US Children

After a long period of decline, the prevalence of high blood pressure in children and adolescents in the United States is rising, according to results of a study funded by the National Institute of Child and Human Development and published in Circulation.^[5] The increase is particularly high for the blood pressure levels defined as "prehypertension." Prehypertension in children has been associated with signs of early target organ damage once they become young adults, the researchers note.

Perhaps the most important association the researchers report is the link between blood pressure increases and the recent rise in childhood obesity. The authors estimated that for each 1-cm increase in waist circumference, the likelihood of high blood pressure increase by 10% and the likelihood of prehypertension increased by 5%. In response to this, lead author Rebecca Din-Dzietham, MD, PhD, MPH (Morehouse School of Medicine, Atlanta, Georgia) and her colleagues urge strong action to prevent development of what they describe as a "major public health problem."

Study Methodology

Din-Dzietham's group used data from a study population consisting of boys and girls aged 8 to 17 years who participated in the National Health Examination, the Hispanic Health and Nutrition Examination Survey (HHANES), and the National Health and Nutrition Examination Survey (NHANES I, II, III, and continuous NHANES) between 1963 and 2002. The surveys were conducted by the National Center for Health Statistics on a nationwide probability sample of the noninstitutionalized US population and based on a complex multistage sampling design. Din-Dzietham and colleagues used the data to examine trends in the age-adjusted prevalence of hypertension and prehypertension in the 8 to 17 year olds, while also looking for trends in various racial/ethnic groups and the impact of increasing obesity on those trends.

Following the 2004 guidelines produced by the National High Blood Pressure Education Working Group on High Blood Pressure in Children and Adolescents of the National Heart, Lung and Blood Institute,^[6] blood pressure cutpoints were classified based on age, gender, and height percentile-specific systolic (SBP) and diastolic blood pressure (DBP) levels. According to this classification scheme, normal blood pressure was defined as having both SBP and DBP < 90th percentile for the particular age group. Prehypertension was defined as either SBP or DBP ≥ 90th percentile but < 95th percentile, or blood pressure ≥ 120/80 mm Hg but < 95th percentile. Hypertension was defined as either SBP or DBP ≥ 95th percentile. Weighted analyses were performed to account for the complex design.

Results

The prevalence of hypertension and prehypertension in children and adolescents showed a downward trend between 1963 and the 1988-1994 survey (NHANES III), but then these indices reversed and increased through 2002. Thus the prevalence of hypertension in all children and adolescents decreased from 11% in the 1976-1980 survey (blacks and whites, NHANES II) and 4.7% in the 1982-1984 survey (Mexican Americans, HHANES) to 2.7% in the 1988-1994 survey (all ethnic groups). By the 1999-2002 survey, however, these declines had reversed and risen to 3.7% (in all ethnic groups, continuous NHANES). Between 1988 and 2002, the age-adjusted prevalence of prehypertension and hypertension increased by 2.3% (P = .0003) and 1% (P = .17), respectively. The increase in prehypertension was significant for blacks and Mexican Americans, and the increase in hypertension was significant for Mexican American males and white females, although the researchers caution that these estimates may not necessarily be reliable in all cases due to small sample sizes.

Obesity. Concurrent with the hypertension trends, obesity was seen to increase from the time of the earliest survey (1963 to 1970), with the blood pressure rise lagging about 10 years behind this trend. In this study, both body mass index (BMI) and waist circumference were significantly associated with hypertension, although the increase in waist circumference (abdominal obesity) explained more of the blood pressure/hypertension increase than the increase in BMI (general obesity). In this study, obesity as measured by BMI or waist circumference was estimated to account for about 44% of the increase in hypertension and for 27% (BMI) and 68% (waist circumference) of the increase in prehypertension.

Implications and Comment

These new findings have implications for the public health burden of cardiovascular disease, particularly the risk of new cardiovascular disease, the researchers believe. "This is a major public health problem," Dr. Din-Dzietham said. "Unless this upward trend in high blood pressure is reversed, we could be facing an explosion of new cardiovascular disease cases in young adults and adults. To reverse the upward trend at the beginning is good, and that's why we need to act now."

In an accompanying editorial, Bonita Falkner, MD (Thomas Jefferson University, Philadelphia)^[7] emphasizes that the current upward trend in the prevalence of high blood pressure among children is concurrent with an increase in childhood obesity and that this study and others "provide evidence for the concept that secular trends in childhood obesity are setting the stage for increasing and premature cardiovascular disease within the US population." However, Falkner says that the downward trend in prehypertension and hypertension from 1963 to 1988, described by Din-Dzietham and colleagues, does not reflect a decrease in prevalence of high blood pressure in children and adolescents. Rather, the downward trend reflects a progression toward a more accurate description of the normal blood pressure distribution in childhood.

Falkner, who was chair of the working group that prepared the latest guidelines for high blood pressure in children and adolescents,^[6] describes how application of previous definitions of blood pressure in children could have led to inflated prevalence estimates. "The recent upward trend in prevalence of high BP [blood pressure] in childhood, which appears to be related to the childhood obesity epidemic, is clearly indicative of a significant emerging public health problem," she says.

Hypertension Frequently Undiagnosed in Children and Adolescents, Study Finds

The diagnosis of hypertension in children is complicated because normal and abnormal blood pressure values in children are a function of age, sex, and height percentile. Clinicians typically cannot remember all the normal blood pressure values for the wide range of children observed in the typical primary care setting, and although blood pressure tables and electronic programs exist, it may be difficult and time-consuming to integrate these tools into a physician's work flow.

The difficulties of diagnosing hypertension in children are underlined by a study, published in JAMA,^[8] which found that within a large, tertiary healthcare system, only about 1 in 4 children and adolescents identified by the investigators as having hypertension had been diagnosed with the condition, according to medical records. Matthew L. Hansen, MD (Case Western Reserve University, Cleveland) and colleagues carried out the study to determine the frequency of undiagnosed hypertension and prehypertension in 14,187 children and adolescents (age 3-18 years) who were observed ≥ 3 times for well-child care between June 1999 and September 2006 in the outpatient clinics in a large academic urban medical system in northeast Ohio. Mean age of the participants in the study was 8.8 years, 50% were African American, and 49% were female.

Age- and height-adjusted SBP and DBP were estimated for each participant according to the National High Blood Pressure Education Working Group on High Blood Pressure in Children and Adolescents guidelines,^[6] and blood pressure percentiles were calculated for each patient based on the expected blood pressure.

Hypertension was defined on the basis of 3 visits as: stage 1 -- SBP to DBP ≥ 95th percentile for age, sex, and height and ≤ 99th percentile plus 5 mm Hg; and stage 2, SBP or DBP ≥ 99th percentile plus 5 mm Hg.

Prehypertension was defined as an average SBP or DBP between the 90th and 95th percentiles, or > 120/80 mm Hg.

Patients were considered to have been diagnosed with hypertension if the problem list, list of diagnoses, or medical history list from any visit contained 1 of the International Classification of Diseases, Ninth Revision (ICD-9) codes related to hypertension.

The researchers found that the criteria for hypertension were met by 507 children (3.6%). Of the children with hypertension, only 131 (26% of the 507) had a diagnosis of hypertension or elevated blood pressure documented in the electronic medical record; put the other way, this means that 376 of 507 participants (74%) had undiagnosed hypertension.

Criteria for prehypertension were met by 485 children (3.4%). Of these children, 55 (11%) had a diagnosis of hypertension or elevated blood pressure documented in the electronic medical record. Manual review of a random sample of charts from 50 patients with undiagnosed hypertension showed 4 (8%) with a note of abnormal blood pressure in the electronic medical record that was not transferred to the problem list, medical history, or visit diagnosis list.

The likelihood that hypertension would be recognized was associated with having an increase of 1% in height-for-age percentile, having an obesity-related diagnosis, and the number of blood pressure readings in the stage 2 hypertension range. The investigators note that older and taller children are more likely to have values ≥ 120/90 mm Hg, which is above normal for adults and likely to be easily identified. Physicians are also probably more likely to look more carefully for abnormal pressure in overweight children, because elevated blood pressure is a frequent comorbid condition.

Dr. Hansen and colleagues stress the importance of identifying elevated blood pressure in children meeting prehypertension or hypertension criteria. It is important because of the increasing prevalence of pediatric weight problems and because secondary hypertension is more common in children than adults, requiring identification and appropriate workup. "If abnormal blood pressure is not identified by a patient's pediatric clinician, it may be years before the abnormal blood pressure is detected, leading to end-organ damage. Because effective treatments for abnormal blood pressure exist, these long-term sequelae can be avoided with early diagnosis." The researchers go on to add:

Although this study identifies the problem of undiagnosed hypertension in children, it also points to the potential of electronic medical records to help address this issue. The relatively poor identification of abnormal blood pressure could be remedied by a clinical decision support algorithm built into an electronic medical record that would automatically review current and prior blood pressures, ages, heights, and sex to determine if abnormal blood pressure criteria had been met. The algorithm could indicate if any abnormal blood pressure ... already existed and prompt the pediatric clinician that the child appears to have undiagnosed abnormal blood pressure. In addition, the clinical decision support algorithm could provide guideline-based evaluation, treatment, and parent/patient education materials to the clinician.

Daytime Blood Pressure Adjusted for Night-Time Blood Pressure Predicts Fatal/Nonfatal Cardiovascular Events

The results of a study published in The Lancet^[9] appear to challenge the consensus that nighttime blood pressure measurements are of greatest predictive value for cardiovascular complications. After analyzing individual data from over 7000 subjects, José Boggia, MD (Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay) and colleagues found that the predictive accuracy of daytime and nighttime blood pressures and the night-to-day blood pressure ratio depended on the outcome under study.

For fatal endpoints, the nighttime blood pressure was more predictive than the daytime blood pressure, and the night-to-day ratio predicted total, cardiovascular, and noncardiovascular mortality. In contrast, for fatal combined with nonfatal outcomes, the daytime blood pressure was as valuable as the nighttime blood pressure, and the night-to-day ratio has little prognostic accuracy.

The researchers used data from the International Database on Ambulatory blood pressure monitoring in relation to Cardiovascular Outcomes, a resource of longitudinal population studies that was set up to investigate the extent that ambulatory blood pressure improves risk stratification.^[10] The data in this analysis came from 7458 participants (mean age 56.8 years) who underwent 24-hour blood-pressure monitoring in 6 prospective population studies carried out in Belgium, Denmark, Sweden, China, Japan, and Uruguay. Of the 3436 (46%) subjects who had hypertension, 1637 (48%) were taking antihypertensive medication.

In the overall study population, median follow-up was 9.6 years. During follow-up, 983 participants died (14 per 1000 person-years) and 943 had a fatal or nonfatal cardiovascular complication (13.6 per 1000 person-years). There were more noncardiovascular than cardiovascular deaths (560 and 387, respectively). Of the cause-specific first cardiovascular events, 51 were fatal strokes and 369 were nonfatal strokes. Cardiac events consisted of 146 fatal and 379 nonfatal events, including 65 fatal and 186 nonfatal cases of acute myocardial infarction, 30 deaths from ischemic heart disease, 30 sudden deaths, 21 fatal and 142 nonfatal cases of heart failure, and 51 cases of surgical or percutaneous coronary revascularization.

Dr. Boggia and his colleagues calculated multivariate-adjusted hazard ratios for daytime and nighttime blood pressure and the systolic night-to-day ratio, while adjusting for cohort and cardiovascular risk factors. They found that:

In fully adjusted models, with correction for nighttime blood pressure, systolic daytime pressure lost prognostic significance for cardiac events, whereas diastolic daytime pressure become nonsignificant for cardiac and coronary events. After adjustment for daytime blood pressure, systolic and diastolic nighttime values were no longer significant for coronary events. With adjustment for the 24-hour blood pressure, systolic and diastolic night-to-day ratio predicted mortality, but not fatal plus nonfatal events. Antihypertensive drug treatment removed the significant association between cardiovascular events and the daytime blood pressure.

Implications

These results suggest that daytime blood pressure, adjusted for nighttime blood pressure, predicts fatal combined with nonfatal cardiovascular events, except in treated patients, in whom antihypertensive drugs might reduce blood pressure during the day, but not at night. One reason for this could be that antihypertensive treatment acts as a major confounder, the researchers suggest. Patients with more severe hypertension or a history of cardiovascular complications are more likely to be treated and at higher risk than other patients, and they take their medications during daytime, and that activity that lowers blood pressure wears off at night. This mechanism leads to a reduced daytime blood pressure, increased nighttime blood pressure, and a decreased night-to-day blood pressure ratio.

Participants with systolic night-to-day ratio value of ≥ 1 or more were older, at higher risk of death, and died at an older age than those whose night-to-day ratio was normal (≥ 0.80 to < 0.90). The researchers suggest that higher nighttime than daytime blood pressure might be a marker rather than a cause of a poor outcome.

Conclusion

Dr. Boggia and his colleagues say that the findings of this study support the conclusions that:

However, the researchers point out that there is no evidence supporting the efficacy of chronotherapy in terms of blood-pressure control or outcome. Furthermore, the classification of patients according to the night-to-day blood pressure ratio greatly depends on arbitrary criteria, is poorly reproducible, and has a different prognostic meaning according to the disease outcome under study, the prevailing 24-hour blood pressure level, and treatment status. They recommend that "in future publications any categorical representation of the night-to-day ratio be supported by continuous analyses adjusted for the 24-hour blood pressure and be stratified for treatment status."

Comment

In an invited commentary on the study,^[11] Stéphane Laurent, MD, PhD (Hôpital Européen Georges Pompidou and Université Paris-Descartes, Paris, France) agrees with Dr. Boggia and colleagues that the main finding, that daytime blood pressure independently predicts the composite of fatal and nonfatal outcomes, might not apply to patients with treated hypertension. Although the investigators did not include cohorts of patients with hypertension and selected general populations instead, Prof. Laurent notes, 22% of the overall study population were being treated for hypertension at baseline and analysis of a significant interaction with antihypertensive treatment status at enrollment was possible.

The contrasting findings in untreated participants and treated patients suggest a need for an additional meta-analysis of individual data for ambulatory blood pressure that includes a substantial number of patients on treatment for hypertension, Prof. Laurent suggests. "Although the findings of Boggia and colleagues are in favor of recording the ambulatory pressure for the whole day, the question arises as to whether 24-hour blood pressure values from patients taking antihypertensive therapy should be interpreted differently from those of untreated participants," he proposes. He believes that the results of the study may have important clinical implications and significantly affect the next guidelines for ambulatory blood pressure measurement.

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