Clinical trial results used to support the current recommendations for target blood pressure don't tell the whole story.
Clinical trial results used to support the current recommendations for target blood pressure don’t tell the whole story.
The recommendation of maintaining blood pressure (BP) of 130/80 mmHg was driven by fear, explained George Bakris, MD, at the 20th Annual Meeting and Clinical Congress of the American Association of Clinical Endocrinologists. Bakris is professor of Medicine at the University of Chicago School of Medicine in Illinois, and serves as director of the Hypertension Center in the Diabetes Institute. “The question is,” posed Bakris, “can we defend 130/80? Does it apply to diabetes?” He explained that while we couldn’t defend 130/80 mmHg, we were afraid to recommend anything less than 140/90 mmHg for fear that physician inertia would result in even higher rates of BP. However, there is a price to being more aggressive, or conservative, when it comes to BP; with increased medication for BP, there are increased side effects.
His talk focused on several cardiovascular (CV) studies with diabetes cohorts. The INVEST trial evaluated CV outcomes in a diabetes subgroup. The group with BP above 140 mmHg had the highest percent of myocardial infarction (MI) and stroke, but there was no statistical difference between the 130-140 mmHg range and those with BP less than 130 mmHg. However, Bakris pointed out that this was a post-hoc study, so it doesn’t provide conclusive evidence. In the ACCOMPLISH study, 60% of patients had type 2 diabetes, with the high-risk group defined as those with previous stroke, MI, CV insult, or other risk factors. Patients received either benazepril combined with amlodipine (B+A) or benazepril combined with hydrochlorothiazide. Results showed that all diabetic patients had a slightly better, albeit nonsignificant, risk reduction in terms of events on the B+A combination, with the greatest impact among high-risk diabetic patients. A second analysis included all patients (not just diabetics) and found that the group with BP less than 130 mmHg did no better than the other groups. In the INVEST study, participants with kidney disease did better with ACC’s compared to diuretics. The data from the ONTARGET study showed a J-shaped curve for CV mortality, MI, and possibly for diabetics, with the lowest risk for patients with systolic BP of 130 mmHg.
Trying to decipher all of these results can be daunting. But Bakris strongly encourages physicians to look at inclusion criteria and not just the trial results. “If you don’t know the inclusion criteria, you can’t say anything about the trial.” He also suggests evaluating study design to see if it was appropriate. Among several conclusions he has reached from his own research and review of the literature is that CV mortality risk doubles with each 20/10 mmHg increase in BP. “It is not true that you reverse everything if you get BP low enough.” Even a 10/5 mmHg reduction in BP reduces the probability of a CV event; a little change can give patients a great benefit, he said. For the elderly, previous recommendations were to maintain BP under 150/80 mmHg, but there has been a lot of pressure to achieve 140/90 mmHg.
The bottom line is it’s tough to recommend 130/80 for everybody. If a person’s individual physiology allows you to take his/her BP lower and the patient understands the risks, then you should try to do it. If it’s too risky due to side effects, excessively low diastolic BP, or other reasons, then don’t. “It’s a judgment call,” explained Bakris. “No clinical trial will tell you what to do.”