High blood pressure is the most important treatable risk factor for diseases of the heart and the arterial system.
Blood pressure recorded over 24 hours predicts these complications more accurately than blood pressure measured on a single occasion.
That is the conclusion of an international study coordinated by Professors Jan A. Staessen and Zhen-Yu Zhang of KU Leuven in Belgium. Dr. Gladys Maestre from the University of Texas, Rio Grande Valley School of Medicine, supervised the study in Venezuela, one of the participating countries.
The study was published in the Journal of the American Medical Association.
An international consortium of scientists followed 11,135 individuals for 14 years.
Study participants included residents of 12 countries in Europe, East Asia, and Latin America.
The researchers compared the predictive accuracy of blood pressure measurements made by a healthcare provider in an office setting, to repeated blood pressure measurements recorded for 24 hours, during both day and night.
The results showed that the probability of heart and vascular disease during follow-up was closely associated with the blood pressure measured over a 24-hour period.
“Although heart and vascular disease are strongly associated with blood pressure, irrespective of how it is measured, until now we did not know which type of blood pressure measurement captured risk in the most accurate way,” Dr. Maestre said.
At the start of the study, investigators made individual blood pressure measurements using all available approaches, and determined other risk factors.
Blood pressure was also recorded over a 24-hour period using automated portable blood pressure monitors.
The number of blood pressure measurements averaged 30 during daytime and 10 during sleep.
One of the advantages of measuring blood pressure during sleep, with individuals lying down in bed, is that the results are not influenced by daytime activities or meals.
This at least partly explains the accuracy of nighttime blood pressure in predicting cardiac and vascular illness.
High blood pressure is the leading treatable risk factor for diseases of the heart and vascular system.
Worldwide, high blood pressure causes 10 million deaths each year, with more than half of that mortality attributable to cardiovascular disease.
The present study is unique in its large sample size and long follow-up period.
The characteristics of participants were similar to those of the populations from which they were enrolled, so the results can be generalized.
“Our research highlights the necessity of using 24-hour measurements to diagnose high blood pressure and to institute and fine tune its treatment,” said Dr. Maestre.
“Nevertheless, most health insurers in the US reimburse 24-hour ambulatory blood pressure monitoring only when blood pressure is found to be high in the clinical setting, but is suspected to be normal otherwise, or if undetected or masked hypertension is suspected.
However, 24 hour ambulatory blood pressure monitoring is cost effective:
It enables the prevention of cardiovascular disease by starting treatment in a timely manner.”
Prevention and improved control of high blood pressure is also cost effective, because hospital-based treatment of the complications of high blood pressure, such as chest pain caused by narrowing of the arteries of the heart, myocardial infarction, and stroke, is expensive.
Furthermore, prevention reduces the risk of premature disability and death, thereby avoiding suffering of patients and their families.
About 30 percent of all adults and 60 percent of people age 60 and over have high blood pressure.
Therefore, ambulatory blood pressure monitoring should be available at all levels of the healthcare delivery chain.
Approximately 54% of strokes and 47% of coronary heart diseases, worldwide, are attributable to high BP.3 Hypertension is a common medical condition; its prevalence increases with age,4,5 and is estimated to affect 65% of those ≥60-years-old.6 The global population is aging.
By 2030, an estimated 20% of the global population will be ≥65-years-old.7
Therefore, the impact of high BP on mortality among older adults is expected to grow over the coming decades.
Recently, the 2013 European Society of Hypertension/European Society of Cardiology Hypertension Guidelines defined a universal target of <140/90 mm Hg for all patients, except the most elderly population segment (target, <150/90 mm Hg for those ≥80-years-old).8
The American Heart Association, American College of Cardiology, Centers for Disease Control and Prevention,9 American Society of Hypertension, and the International Society of Hypertension10also supported the treatment goals associated with this guideline.
However, based on evidence from randomized controlled trials, the 2014 Evidence-Based Guideline for the Management of High Blood Pressure in Adults (Report from the Panel Members Appointed to the Eighth Joint National Committee (JNC 8)) raised the target to <150/90 mm Hg for adults ≥60-years-old.11
In contrast with the recommendation in the 2014 JNC 8 but in accordance with the 2013 ESH/ESC Hypertension Guidelines, the 2015 Guidelines of the Taiwan Society of Cardiology and the Taiwan Hypertension Society for the Management of Hypertension recommends a target BP of <140/90 mm Hg for those aged 60 to 80 years and a BP target of BP <150/90 mm Hg for those aged ≥80 years.12
Thus, the optimal BP target for older adults has not yet been established. Most guidelines are based on evidence from randomized controlled trials, which are considered the gold standard of evidence for making treatment decisions.
However, they often include a select population with limited generalizability.
This is particularly relevant for older adults, a population comprised of individuals with heterogeneous health statuses and high prevalences of chronic diseases.
Older adults have been underrepresented in clinical trials,13 resulting in treatment decisions being extrapolated from data involving much younger individuals.
Therefore, this study might be used to complement randomized trials and extends the knowledge of the association between hypertension and mortality risk among older adults.
The objective of this study was to investigate the associations between BP and all-cause, CVD, and expanded-CVD mortalities among community-dwelling older adults to determine the appropriate BP range with the lowest risk of mortality.
Expanded-CVD disease was considered because of the high likelihood of classifying death due to CVD in patients with diabetes as death due to diabetes, whereas, in patients with kidney disease, there is a high likelihood of classifying the death as due to kidney disease.14
Furthermore, our large sample size allowed us to perform stratified analyses and investigate the associations among different subgroups.
Hazard Ratios (HRs) for Mortality Risks by Hypertension Stage
During an average of 3.28 (SD, 1.30) years of follow-up, 3830 persons (4.95%) died during the study period. Of the total deaths, 876 (22.9%) were ascribed to CVD and 1115 (29.1%) were expanded-CVD-related. Crude all-cause, CVD, and expanded-CVD mortality rates (of 253,741 person-years) were 15.1 (3830 persons), 3.5 (876 persons), and 4.4 (1115 persons) per 1000 person-years, respectively. The characteristics of the participants with expanded-CVD mortality after stratification by hypertension stage are shown in Supplementary Table 1, http://links.lww.com/MD/A532.
Table Table2 shows the incidence rate ratios (IRRs) and HRs of mortalities for different stages of hypertension.
The IRRs for mortality risks were significantly higher for the stage 2–3 hypertension group. After adjusting for age and sex, the HRs for expanded-CVD mortality were significantly higher for the stage 2–3 hypertension group. In the fully adjusted model, the mortality risk for the stage 2–3 hypertension group remained substantial (all-cause mortality: HR, 1.23; 95% confidence interval [CI], 1.10–1.37; CVD mortality: HR, 1.31; 95% CI: 1.05–1.64; expanded-CVD mortality: HR, 1.40; 95% CI: 1.15–1.71). In the sensitivity test, after excluding subjects who died within the first and second years of baseline BP measurement, the results remained robust.
When the data of history of hypertension (48.1%) were used for analysis, compared to those with no hypertension history (51.9%), the CVD and expanded-CVD mortality risks were significantly higher among those with a history of hypertension (HR: 1.06, 95% CI: 0.98–1.13 for all-cause mortality; HR: 1.38, 95% CI: 1.20–1.60 for CVD-mortality; and HR: 1.38, 95% CI: 1.21–1.57 for expanded-CVD mortality).
We further classified those with BP ≥ 140/90 mm Hg during physical examination and those with a history of hypertension as the hypertension group (59.6%), and the others as the nonhypertension group (40.4%).
Compared to the nonhypertension group, the hypertension group had significantly higher mortality risks (HR: 1.10, 95% CI: 1.02–1.17 for all-cause mortality; HR: 1.42, 95% CI: 1.23–1.65 for CVD mortality; and HR: 1.44, 95% CI: 1.26–1.64 for expanded-CVD mortality).
More information: Wen-Yi Yang et al, Association of Office and Ambulatory Blood Pressure With Mortality and Cardiovascular Outcomes, JAMA (2019). DOI: 10.1001/jama.2019.9811
Journal information: Journal of the American Medical Association
Provided by KU Leuven