What is a better predictor of mortality: ambulatory or office-based measurement of blood pressure?
This study supports the guidelines recommending that treatment decisions be based on ambulatory blood pressure (BP) measurements rather than in-office BP results. The difference between the 2 measurements in this cohort was 19/11 mm Hg, which is enough to change the decision to prescribe a medication at all, or to add a second or third medication. (LOE = 2b)
Banegas JR, Ruilope LM, de la Sierra A, et al. Relationship between clinic and ambulatory blood-pressure measurements and mortality. N Engl J Med 2018;378:1509-1520.
Study design: Cohort (prospective)
Funding source: Government
How we measure things matters: For example, nonfasting lipid levels are a better predictor of mortality than fasting lipid levels. Recent guidelines for hypertension, including from the U.S. Preventive Services Task Force, have emphasized the need to confirm elevated BPs in most patients using some form of ambulatory BP monitoring. This study used data from a large Spanish hypertension registry to look at the association between clinic BPs, ambulatory blood BPs, and mortality. The registry includes adults with an indication for ambulatory BP monitoring, such as suspected white coat hypertension, borderline or labile hypertension, or hypertension refractory to treatment. The registry supplies data on clinic BPs, measured by automated devices after 5 minutes of seated rest, and 24-hour ambulatory BP measurements. These data were linked to national vital statistics databases to determine cardiovascular and all-cause mortality. The analysis was adjusted for comorbidities, age, sex, tobacco use, and body mass index. The mean age of patients was 58 years, 58% were male, and only 11% had a diagnosis of cardiovascular disease. During a median 4.7 year follow-up, there were a total of 3808 deaths including 1295 cardiovascular deaths. The mean ambulatory BP was 129/76, compared with 148/87 in the clinic. Recall, the clinic BPs were measured by an automated device after 5 minutes of rest, yet they were still far higher than the ambulatory measurements. In the fully adjusted model that adjusted for clinic BPs, the hazard ratio for all-cause mortality was 1.58 (95% CI 1.56 - 1.60) for the ambulatory systolic BP versus 1.02 (1.00 - 1.04) for the clinic systolic BP adjusted for ambulatory BP. A similar pattern was seen for diastolic BPs. The inflection point for an increase in both cardiovascular and all-cause mortality is at a systolic BP of 140 to 160. Mortality was not increased in patients with controlled hypertension, but was increased in those with both white-coat and masked (normal in clinic, abnormal at home) hypertension.
Mark H. Ebell, MD, MS
University of Georgia
Is a single office blood pressure measurement reliable to assess hypertension?
Don't rely on a single blood pressure measurement. The first blood pressure reading taken during an office visit will be substantially different than subsequent readings in almost half of typical patients, and if relied upon will result in 1 in 8 patients being falsely labeled as hypertensive. (LOE = 1b)(www.essentialevidenceplus.com)
Burkhard T, Mayr M, Winterhalder C, Leonardi L, Eckstein J, Vischer AS. Reliability of single office blood pressure measurements. Heart 2018;104(14):1173-1179.
Study design: Cross-sectional
Funding source: Self-funded or unfunded
Setting: Outpatient (primary care)
The authors enrolled 1000 consecutive patients who presented for internal medicine, obstetric, or gynecologic care, though only 802 patients completed the study. Each patient, after 5 minutes of rest, had 4 consecutive blood pressure measurements, 2 minutes apart, by 1 of 13 trained physicians. The first systolic blood pressure was more than 10 mm Hg higher than the mean of subsequent measurements in 23.9% of patients; in total, 45.9% of patients had a systolic difference of more than 5 mm Hg. Similarly, diastolic blood pressures were more than 10 mm Hg different in 4.4% of patients; in total, 21.6% of patients had a difference of more than 5 mm Hg. More important, hypertension would have been diagnosed in error in 1 in 8 patients (12%) if only the first measurement had been obtained, and 2% of patients would have had their hypertension undiagnosed by the single measurement.
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine
Alex Shreiber, PharmD
In patients with high blood pressure, does a second reading show lower results?
If you're not rechecking high blood pressures, you should. In fact, set your electronic health record to remind you to do it. In this large study, when reminded, clinicians rechecked elevated blood pressures 83% of the time, finding a median drop in blood pressure of 8 mm Hg during the same visit. That drop is equivalent to a typical reduction in blood pressure with pharmacologic treatment over time, and resulted in one-third fewer patients being labeled with high blood pressure at that visit. (LOE = 2b)(www.essentialevidenceplus.com)
Einstadter D, Bolen SD, Misak JE, Bar-Shain DS, Cebul RD. Association of repeated measurements with blood pressure control in primary care. JAMA Intern Med 2018 doi:10.1001/jamainternmed.2018.0315. [Epub ahead of print]
This study was conducted in primary care offices of a large US health system. The electronic health record was set to remind clinicians to recheck the blood pressure of a patient when a value greater than 140/90 mm Hg was documented. The reminder worked: Clinicians rechecked high blood pressures 83% of the time. The authors then evaluated the effect of this simple intervention on 38,260 patients, average age 61 years, 39% of whom had a high initial reading. With repeated measurement, the median drop in blood pressure was 8 mm Hg (interquartile range 2 mm Hg - 17 mm Hg) and 36% of patients no longer had a blood pressure of 140/90 mm Hg or higher.
At what systolic blood pressure should we begin treatment for the most benefit?
Beginning antihypertensive treatment when the systolic blood pressure (SBP) is greater than 140 mm Hg delays death and prevents major cardiovascular events in some people without pre-existing heart disease; in patients with existing heart disease it prevents further events, but does not extend life. These results may appear to conflict with those from SPRINT trial, which found benefit with lowering SBP to below 120 mm Hg. However, the SPRINT investigators measured blood pressure using automated devices which give readings 10 mm Hg to 20 mm Hg lower than typical office measurements. So, the goal of less than 120 mm Hg in the SPRINT study is likely to be very similar to the goal of less than 140 mm Hg in this study. (LOE = 1a)(www.essentialevidenceplus.com)
Brunstrom M, Carlberg B. Association of blood pressure lowering with mortality and cardiovascular disease across blood pressure levels. A systematic review and meta-analysis. JAMA Intern Med 2018;178(1):28-36.
Study design: Meta-analysis (randomized controlled trials)
Funding source: Foundation
Setting: Various (meta-analysis)
The authors followed PRISMA guidelines to search 3 databases, including Cochrane CENTRAL, as well as reference lists of identified studies to identify all randomized trials with at least 1000 patient-years of follow-up that compared drug treatment with placebo or compared blood pressure targets against one another. Two researchers independently extracted the data and assessed the quality of the research (more than two-thirds of the studies had a low risk of bias). They identified 74 studies enrolling 306,273 patients (60.1% men, average age 63.6 years). In patients without pre-existing heart disease (ie, primary prevention), lowering SBP that was initially greater than 140 mm Hg decreased the risk of death (relative risk [RR] = .93, 95% CI -.88 to 1.0 if SBP > 160 mm Hg; RR = 0.87, .75 to 1.00 if SBP 140 - 159 mm Hg) and major cardiovascular events (RR = .78, .7 to .87 if > 160 mm Hg; RR = .88, .8 - .96 if 140 - 159 mm Hg). Treating SBP that was initially less than 140 mm Hg did not affect morbidity or mortality. In patients with previous coronary heart disease and a mean SBP of 138 mm Hg, treatment reduced the risk for further major cardiovascular events (RR = .9; .84 to .97), but did not extend life. There was a high degree of heterogeneity among these trial results, reducing our confidence in the results. There was some evidence of publication bias in studies that evaluated the effect on major cardiovascular events, meaning that studies failing to show a difference in outcomes were not published.
Is lower systolic blood pressure associated with better outcomes in elderly patients who take antihypertension medications?
In this small cohort study of patients older than 85 years, lower systolic blood pressure during treatment with antihypertensive medications is associated with higher death rates and greater cognitive decline. (LOE = 1b-)(www.essentialevidenceplus.com)
Streit S, Poortvliet RKE, Gussekloo J. Lower blood pressure during antihypertensive treatment is associated with higher all-cause mortality and accelerated cognitive decline in the oldest-old data from the Leiden 85-plus Study. Age Ageing 2018;47(4):545-550.
Are you tired of all the ping-ponging, guideline-based blood pressure targets? Unfortunately, this study won't improve your fatigue. These researchers assembled a cohort of 570 residents of Leiden in the Netherlands who turned 85 years of age between 1997 and 1999. They excluded people who died within 3 months of enrollment and those who had no blood pressure measurement at baseline. At baseline, and periodically over the course of 5 years of follow up, the researchers collected all kinds of information: sociodemographics, medical diagnoses, medications, mental status, grip strength (as a proxy for frailty), blood pressure, and so forth. They assessed the main outcome—death from any cause—by using municipal records. Slightly fewer than half of the residents (44%) took antihypertensive medications at baseline; these patients were more likely to have other cardiovascular disorders than those not taking antihypertensive medications (62% vs 36%). During the 5 years of follow-up, 263 (46%) participants died. For those taking antihypertensive medications, all-cause mortality was significantly higher with decreasing systolic blood pressure (hazard ratio 1.29 per 10 mmHg lower systolic blood pressure; 95% CI 1.15 - 1.46). For the residents who were not taking antihypertensive medications, there was no significant correlation between systolic blood pressure and all-cause mortality. Additionally, the patients taking antihypertensives had more rapid cognitive decline with lower systolic blood pressure. Although many explanations for the differences in treatment thresholds are given by the various guidelines, one is how we value clinical trial versus observational data: The guidelines that promulgate lower blood pressure targets are more likely to value observational data. The data from this study are subject to many of the biases inherent in cohort studies, but they should moderate the enthusiasm for lower blood pressure targets.
Henry C. Barry, MD, MS
Michigan State University
East Lansing, MI
POEMs are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, please see http://www.essentialevidenceplus.com(www.essentialevidenceplus.com).
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