Blood pressure targets for hypertension in older adults

Scott R Garrison, Michael R Kolber, Christina S Korownyk, Rita K McCracken, Balraj S Heran, G Michael Allan

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 We also contacted authors of relevant papers regarding further published and unpublished work.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. 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.