Identifying the most appropriate blood pressure (BP) targets for treated hypertensive individuals has long been a topic of heated discussion. It’s natural to assume that lowering BP would lead to a lower risk for cardiovascular and mortality outcomes, but is there a point when aggressively lowering BP actually becomes ineffective—or even harmful?

A recent recommendation by the Eighth Joint National Committee (JNC8) to loosen BP treatment targets to <150/90 mm Hg among people aged 60 years or older supports the idea that stricter BP control is not necessary or beneficial in all populations.

To assess the impact of treating to lower BP targets, John J. Sim, MD, and colleagues analyzed the association of actual, on-treatment BP levels with subsequent risks of mortality and end-stage renal disease (ESRD) in a large, ethnically diverse population of individuals receiving medical treatment for hypertension.

Nearly 400,000 hypertensive patients within the Kaiser Permanente Southern California health system were enrolled in this retrospective cohort study. At baseline, the mean BP was 131/73 mm Hg with standard deviations for systolic BP (SBP; 11 mm Hg) and diastolic BP (DBP; 8 mm Hg). Over the observation period, 83%  of patients were considered “controlled” with an SBP <140 mm Hg.

During follow-up (which ranged from 3-5 years), mortality occurred in 25,182 (6.3%) patients and ESRD in 4,957 (1.2%). In those who died, mean SBP decreased 7 mm Hg during the 60 days prior to death (124 vs. 131 mm Hg; p < 0.01), with a slightly less pronounced DBP decrease (67 vs. 70 mm Hg; p < 0.01).

After adjusting for risk factors and comorbidities, the investigators found that patients in both the lowest and the highest SBP groups (<110 mm Hg and ≥170 mm Hg) had the greatest rates of mortality and ESRD, compared to patients with SBP 130-139 mm Hg (TABLE).

There was a U-shaped curve for the composite outcome of mortality/ESRD bottoming at SBP 130-139 mm Hg and at DBP 60-79 mm Hg, with incremental risk increases in both directions. Within this range, a BP of 137/71 mm Hg was associated with the lowest risk of mortality and ESRD.

The traditional guiding principle of BP treatment has been “the lower, the better,” but, as Drs. Andersson and Vasan write in an editorial accompanying Dr. Sim’s study, “it is obvious that driving BP too low with medications can lead to adverse effects.” Overly aggressive BP-lowering can lead to orthostatic hypotension, and lowering diastolic BP below 80-85 mm Hg has been suggested to increase the risk of myocardial infarction in some groups.

“We need further studies to establish the optimal BP treatment target for individuals with various comorbidities,” they added. “It may make sense to treat younger people with fewer comorbidities more aggressively than older individuals or people with a large burden of comorbidity, but the exact numerical BP targets are yet to be determined.”

The current study, for example, demonstrated that optimal BP levels were lower for individuals <70 years of age (compared to ≥70 years), for individuals with diabetes, and for individuals with low comorbidity burden. “While current US guidelines emphasize the upper limits of therapeutic goals, the potential dangers of overtreatment may need to be considered,” Dr. Sim and authors noted.

Andersson C, Vasan RS. J Am Coll Cardiol. 2014;64:598-600.
Sim JJ, Shi J, Kovesdy CP, et al. J Am Coll Cardiol. 2014;64:588-97.