Review question
What is the optimal blood pressure (BP) target when treating older adults with high blood pressure?
Background
Elevated BP in older adults is common and higher pressures increase the risk of adverse health events such as stroke, heart attack, heart failure, and death. Lowering BP with drugs has been shown to reduce the risk of these serious health events but the optimal BP target when treating older adults is not known.
Study characteristics
We systematically retrieved all randomised trials that compared the effect of a higher BP target (upper BP number less than 150 to 160 mmHg) with a conventional lower BP target (upper BP number less than140 mmHg) in people over the age of 65 years. The evidence is current to February 2017.
Key results
We found three randomised trials (the 'gold standard' of medical evidence) that investigated this question in a total of 8221 older adults (average age 75 years, 59% female). We did not find a difference between the higher BP target and the conventional lower BP target, however an important difference favoring the lower BP target could not be ruled out.
Quality of the evidence
We judged the pooled evidence to be of low-quality and not able to adequately answer the question as to which target BP was better. More good-quality trials addressing this question are needed.
At the present time there is insufficient evidence to know whether a higher BP target (less than150 to 160/95 to 105 mmHg) or a lower BP target (less than 140/90 mmHg) is better for older adults with high BP. Additional good-quality trials assessing BP targets in this population are needed.
Eight out of 10 major antihypertensive trials in older adults attempted to achieve a target systolic blood pressure (BP) less than 160 mmHg. Collectively these trials demonstrated benefit for treatment, as compared to no treatment, for an older adult with BP greater than 160 mmHg. However an even lower BP target of less than 140 mmHg is commonly applied to all age groups. At the present time it is not known whether a lower or higher BP target is associated with better cardiovascular outcomes in older adults.
To assess the effects of a higher (less than 150 to 160/95 to 105 mmHg) BP target compared to the lower BP target of less than 140/90 mmHg in hypertensive adults 65 years of age or older.
The Cochrane Hypertension Information Specialist searched the following databases for randomised controlled trials up to February 2017: the Cochrane Hypertension Specialised Register, MEDLINE, Embase, ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform. We also contacted authors of relevant papers regarding further published and unpublished work.
Randomised trials, of at least one year's duration, conducted on hypertensive adults aged 65 years or older, which report the effect on mortality and morbidity of a higher systolic or diastolic BP treatment target (whether ambulatory, home, or office measurements) in the range of systolic BP less than 150 to 160 mmHg or diastolic BP less than 95 to 105 mmHg as compared to a lower BP treatment target of less than 140/90 mmHg or lower.
Two authors independently screened and selected trials for inclusion, assessed risk of bias, and extracted data. We combined data for dichotomous outcomes using the risk ratio (RR) with 95% confidence interval (CI) and for continuous outcomes we used mean difference (MD). Primary outcomes were all-cause mortality, stroke, institutionalisation, and cardiovascular serious adverse events. Secondary outcomes included cardiovascular mortality, non-cardiovascular mortality, unplanned hospitalisation, each component of cardiovascular serious adverse events separately (including cerebrovascular disease, cardiac disease, vascular disease, and renal failure), total serious adverse events, total minor adverse events, withdrawals due to adverse effects, systolic BP achieved, and diastolic BP achieved.
We found and included three unblinded randomised trials in 8221 older adults (mean age 74.8 years), in which higher BP targets of less than 150/90 mmHg (two trials) and less than 160/90 mmHg (one trial) were compared to a lower target of less than 140/90 mmHg. Treatment to the two different BP targets over two to four years failed to produce a difference in any of our primary outcomes, including all-cause mortality (RR 1.24 95% CI 0.99 to 1.54), stroke (RR 1.25 95% CI 0.94 to 1.67) and total cardiovascular serious adverse events (RR 1.19 95% CI 0.98 to 1.45). However, the 95% confidence intervals of these outcomes suggest the lower BP target is probably not worse, and might offer a clinically important benefit. We judged all comparisons to be based on low-quality evidence. Data on adverse effects were not available from all trials and not different, including total serious adverse events, total minor adverse events, and withdrawals due to adverse effects.