Effect of Elevated Blood Pressure on Lifetime Risk for Cardiovascular Disease

Abstract & Commentary

By Harold L. Karpman, MD, FACC, FACP, Clinical Professor of Medicine, UCLA School of Medicine. Dr. Karpman serves on the speakers bureau for Forest Laboratories.

Synopsis: Individuals who experienced increases in blood pressure in middle age have an associated higher remaining lifetime risk for cardiovascular disease (CVD), especially if untreated. Decreases in an elevated blood pressure in middle age will result in a significant lowering of the remaining lifetime risk for CVD.

Source: Allen N, et al. Impact of blood pressure and blood pressure change during middle age on the remaining lifetime risk for cardiovascular disease. The Cardiovascular Lifetime Risk Pooling Project. Circulation 2012;125:37-44.

Cardiovascular disease (CVD) mortality rates have decreased over the past four decades, yet CVD remains the leading cause of death and functional disability and is responsible for more than one-third of all deaths in the United States.1 The lifetime risk (LTR) for CVD among Caucasians has been estimated to be one in two for men and one in three for women2 and it appears to be at least as high among African Americans.3 The LTR for CVD, particularly stroke, increases dramatically with increasing blood pressure (BP). The risk of developing CVD is twice as high among middle-aged individuals with stage II hypertension than it is in those individuals with optimal BP levels.4

Allen and colleagues investigated how changes in BP during middle age affect LTR for CVD and the frequency of occurence of CAD and stroke by pooling and evaluating data from seven diverse U.S. cohort studies.5 They recognized that the systolic BP generally increases linearly with age and that individuals with higher systolic BPs experience the largest increases in the LTR for CAD. However, very little information had previously been published about how changes in BP during middle age may affect the LTR for CVD. Rather than simply evaluating the effects of high BP on LTR for CVD by taking a single measurement of BP during middle age, they evaluated the effects that changes in BP had over an average of 14 years on the LTR for CVD starting at age 55 by following 61,585 men and women for 700,000 person years. Individuals who maintained or decreased their BP to normal levels had the lowest LTR for CVD (22%-41%), compared with individuals who either had or developed hypertension by 55 years of age (42%-69%), suggesting a dose-response effect for the length of time at high BP levels.

Commentary

The results obtained from this study are particularly meaningful because they were obtained from large diverse samples of population-based cohorts, which included almost 700,000 person-years of follow-up. In addition, because the studies were relatively recent, they provide more current estimates of LTR for CVD than were obtained from earlier studies. Equally important, the longitudinal BP measurements were measured over an average span of 14 years during middle age. It should be recognized that most of the follow-up information was obtained before the widespread use of antihypertensive and lipid-lowering therapies and, therefore, current results may be even more beneficial because of improved effects of more contemporary treatment regimens. Individuals who were able to either maintain controlled BPs or decrease their elevated BP to normal BP levels during middle age had the lowest LTR for CVD whereas individuals who experienced an increase in BP had higher LTRs for CVD. Therefore, taking BP measurements into account in all patients — but especially those who are middle aged — can provide more accurate estimates for LTR for CVD. This information represents a step forward in helping the medical profession develop individualized risk-prediction strategies.

In summary, the data presented in this article5 clearly support the widespread clinical impression that avoiding hypertension at any age or lowering an existing and elevated BP into a properly controlled range will significantly improve the LTR for CVD.

References

1. Roger VL, et al. Heart disease and stroke statistics — 2011 update: A report from the American Heart Association. Circulation 2011;123:e18-e209.

2. Lloyd-Jones DM, et al. Lifetime risk of developing coronary heart disease. Lancet 1999;353:89-92.

3. Lloyd-Jones DM, et al. Risk factor burden in middle-age and lifetime risk for cardiovascular and non-cardiovascular death (Chicago Heart Association Detection Project in Industry). Am J Cardiol 2007;99:535-540.

4. Berry JD, et al. Lifetime risks of cardiovascular disease. N Engl J Med 2012;366:321-329.

5. Allen N, et al. Impact of blood pressure and blood pressure change during middle age on the remaining lifetime risk for cardiovascular disease. The Cardiovascular Lifetime Risk Pulling Project. Circulation 2012;125:37-44.