CHICAGO – The next time the U.S. hypertension management guideline gets revised, possibly within another couple of years, it may abandon the current approach of focusing primarily on a person’s blood pressure numbers and center instead on assessing a patient’s overall cardiovascular risk and using that status to guide the need for antihypertensive treatment and how aggressively it is applied.
In short, what some preventive cardiologists see coming down the pike is a blood pressure management guideline that follows the same path carved by the cholesterol management guideline issued by the American College of Cardiology and American Heart Association in 2013 (Circulation 2014 [doi: 10.1161/01.cir.0000437738.63853.7a]) that linked use of lipid-lowering treatment with a statin mostly to a patient’s atherosclerotic cardiovascular disease (ASCVD) risk rather than to their level of LDL cholesterol.
Mitchel L. Zoler/Frontline Medical News
Dr. Kunal N. Karmali
One example of the evidence driving this revisionist approach to thinking about hypertension definition came in a report at the American Heart Association Scientific Sessions that showed “a blood pressure treatment strategy focused just on blood pressure leaves substantial CVD risk unaddressed,” said Dr. Kunal N. Karmali, a cardiologist at Northwestern University, Chicago. “Multivariate risk estimation may help identify types of individuals who are likely to benefit from risk-reducing therapy across the spectrum of blood pressure.”
Dr. Karmali and his associates ran their analysis using data from two well-defined U.S. population data bases that included long-term follow-up, the Atherosclerosis Risk in Communities study and the Framingham Offspring Study, which together provided data for 18,898 people. The researchers categorized these people by their baseline systolic blood pressures into six groups, from below 120 mm Hg to 160 mm Hg and above, and calculated each person’s risk for an incident ASCVD event according to their baseline ASCVD risk score using the risk calculator that accompanied release of the 2013 cholesterol management guidelines. By subtracting the baseline risk–derived prediction of the CVD event rate from the actual number of events during follow-up, Dr. Karmali’s group came up with an estimate of the level of “excess” risk for people within each 10 mm Hg blood pressure stratum.
Ten-year follow-up of the two cohorts identified 739 ASCVD events, of which more than 500 were “excess;” the people in the two cohorts had substantially more ASCVD events than would have been predicted by their risk factors alone. These excess events occurred at all levels of blood pressure. The 6,656 people with baseline systolic blood pressures of 120-139 mm Hg, 35% of the people included in the study, had 45% of the excess events, Dr. Karmali reported.
While people with blood pressures of 120-139 mm Hg would generally not be candidates for antihypertensive treatment based on the existing U.S. guideline (JAMA 2014;311[5]:507-20), a sizable majority, 73%, had high baseline ASCVD risk levels, with predicted 10-year CVD rates of 7.5% or greater.
“An implication of this finding is to think beyond just blood pressure,” Dr. Karmali said. “You need to consider multiple risk factors and use overall risk assessment to inform your management decisions. Looking at just the single risk factor of blood pressure doesn’t capture the true benefits of treatment and weigh that against the risks from treatment,” he said in an interview.
He gave the example of an otherwise healthy woman aged 40 years with a systolic blood pressure of 142 mm Hg, who clearly has a different 10-year risk level than a man aged 70 years who has diabetes and smokes and also has a systolic pressure of 142 mm Hg.
“For cholesterol, we now direct our interventions at people who are at the highest risk, but for blood pressure we still focus on just the single number. Multivariate risk assessment would allow us to direct the interventions at the people who are more likely to benefit,” Dr. Kamali said.
Other recent analyses have also supported this approach, he noted. For example, a metaanalysis published in August used data from nearly 52,000 people collected in 11 studies to show that blood pressure–lowering treatment had a very similar impact on reducing future cardiovascular disease events regardless of a person’s baseline cardiovascular risk level (Lancet 2014;384:591-8).
For middle-aged adults and older people, “I think we would become much more efficient in our selection of people with modestly elevated blood pressure [who need drug treatment] by considering their global risk,” said Dr. Donald M. Lloyd-Jones, professor and chairman of preventive medicine at Northwestern University, and a collaborator on Dr. Karmali’s study.
Another advantage of a risk-based approach to blood pressure management over a number-based approach is that “putting blood pressure into the global context of risk makes me think about global risk management, and that is where clinicians need to move,” Dr. Lloyd-Jones said in an interview. “It’s not just, ‘get a number, treat it, and you’re done.’ You need to also think about statin treatment.”