blood pressure

IMPORTANCE:

Automated office blood pressure (AOBP) measurement involves recording several blood pressure (BP) readings using a fully automated oscillometric sphygmomanometer with the patient resting alone in a quiet place. Although several studies have shown AOBP measurement to be more accurate than routine office BP measurement and not subject to a "white coat effect," the cumulative evidence has not yet been systematically reviewed.

OBJECTIVE:

To perform a systematic review and meta-analysis to examine the association between AOBP and office BP readings measured in routine clinical practice and in research studies, and ambulatory BP recorded during awake hours, as the latter is a standard for predicting future cardiovascular events.

DATA SOURCES:

The MEDLINE, Embase, and Cochrane Library were searched from 2003 to April 25, 2018.

STUDY SELECTION:

Studies on systolic and diastolic BP measurement by AOBP in comparison with awake ambulatory BP, routine office BP, and research BP measurements were included if they contained 30 patients or more.

DATA EXTRACTION AND SYNTHESIS:

Study characteristics were abstracted independently and random effects meta-analyses and meta-regressions were conducted.

MAIN OUTCOMES AND MEASURES:

Pooled mean differences (95% CI) of systolic and diastolic BP between types of BP measurement.

RESULTS:

Data were compiled from 31 articles comprising 9279 participants (4736 men and 4543 women). In samples with systolic AOBP of 130 mm Hg or more, routine office and research systolic BP readings were substantially higher than AOBP readings, with a pooled mean difference of 14.5 mm Hg (95% CI, 11.8-17.2 mm Hg; n = 9; I2 = 94.3%; P < .001) for routine office systolic BP readings and 7.0 mm Hg (95% CI, 4.9-9.1 mm Hg; n = 9; I2 = 85.7%; P < .001) for research systolic BP readings. Systolic awake ambulatory BP and AOBP readings were similar, with a pooled mean difference of 0.3 mm Hg (95% CI, -1.1 to 1.7 mm Hg; n = 19; I2 = 90%; P < .001).

CONCLUSIONS AND RELEVANCE:

Automated office blood pressure readings, only when recorded properly with the patient sitting alone in a quiet place, are more accurate than office BP readings in routine clinical practice and are similar to awake ambulatory BP readings, with mean AOBP being devoid of any white coat effect. There has been some reluctance among physicians to adopt this technique because of uncertainty about its advantages compared with more traditional methods of recording BP during an office visit. Based on the evidence, AOBP should now be the preferred method for recording BP in routine clinical practice.

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BACKGROUND:

Hypertension is a prominent preventable cause of premature morbidity and mortality. People with hypertension and established cardiovascular disease are at particularly high risk, so reducing blood pressure below standard targets may be beneficial. This strategy could reduce cardiovascular mortality and morbidity but could also increase adverse events. The optimal blood pressure target in people with hypertension and established cardiovascular disease remains unknown.

OBJECTIVES:

To determine if 'lower' blood pressure targets (≤ 135/85 mmHg) are associated with reduction in mortality and morbidity as compared with 'standard' blood pressure targets (≤ 140 to 160/ 90 to 100 mmHg) in the treatment of people with hypertension and a history of cardiovascular disease (myocardial infarction, angina, stroke, peripheral vascular occlusive disease).

SEARCH METHODS:

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to February 2017: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched the Latin American and Caribbean Health Science Literature Database (from 1982) and contacted authors of relevant papers regarding further published and unpublished work. There were no language restrictions.

SELECTION CRITERIA:

We included randomized controlled trials (RCTs) with more than 50 participants per group and at least six months follow-up. Trial reports needed to present data for at least one primary outcome (total mortality, serious adverse events, total cardiovascular events, cardiovascular mortality). Eligible interventions were lower target for systolic/diastolic blood pressure (≤ 135/85 mmHg) compared with standard target for blood pressure (≤ 140 to 160/90 to 100 mmHg).Participants were adults with documented hypertension or who were receiving treatment for hypertension and cardiovascular history for myocardial infarction, stroke, chronic peripheral vascular occlusive disease or angina pectoris.

DATA COLLECTION AND ANALYSIS:

Two review authors independently assessed search results and extracted data using standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS:

We included six RCTs that involved a total of 9795 participants. Mean follow-up was 3.7 years (range 1.0 to 4.7 years). Five RCTs provided individual patient data for 6775 participants.We found no change in total mortality (RR 1.05, 95% CI 0.90 to 1.22) or cardiovascular mortality (RR 0.96, 95% CI 0.77 to 1.21; moderate-quality evidence). Similarly, no differences were found in serious adverse events (RR 1.02, 95% CI 0.95 to 1.11; low-quality evidence). There was a reduction in fatal and non fatal cardiovascular events (including myocardial infarction, stroke, sudden death, hospitalization or death from congestive heart failure) with the lower target (RR 0.87, 95% CI 0.78 to 0.98; ARR 1.6% over 3.7 years; low-quality evidence). There were more participant withdrawals due to adverse effects in the lower target arm (RR 8.16, 95% CI 2.06 to 32.28; very low-quality evidence). Blood pressures were lower in the lower' target group by 9.5/4.9 mmHg. More drugs were needed in the lower target group but blood pressure targets were achieved more frequently in the standard target group.

AUTHORS' CONCLUSIONS:

No evidence of a difference in total mortality and serious adverse events was found between treating to a lower or to a standard blood pressure target in people with hypertension and cardiovascular disease. This suggests no net health benefit from a lower systolic blood pressure target despite the small absolute reduction in total cardiovascular serious adverse events. There was very limited evidence on adverse events, which lead to high uncertainty. At present there is insufficient evidence to justify lower blood pressure targets (≤ 135/85 mmHg) in people with hypertension and established cardiovascular disease. More trials are needed to answer this question.