September 04, 2013

AMSTERDAM — An analysis of the Reasons for Geographic and Racial Differences in Stroke (REGARDS) observational study showed there was a significant twofold increased risk of cardiovascular disease in elderly patients with systolic blood pressures >150 mm Hg as well as a significantly increased risk of coronary heart disease incidence.

While stroke rates were not significantly increased in elderly patients with higher blood pressures, there was an increased risk of all-cause mortality among individuals 55 to 74 years of age with systolic blood pressures >140 mm Hg. The results, presented here today at the European Society of Cardiology (ESC) 2013 Congress, are considered hypothesis-generating at this point, say investigators, but do suggest a new standard for treating older patients.

"The results of the REGARDS cohort study generate a hypothesis that for all patients older than 55 years of age, the recommended level of systolic blood pressure be less than 140 mm Hg, with optimal values possibly between 120 and 139 mm Hg," said Dr Maciej Banach (Medical University of Lodz, Poland) during an update session of clinical trials at the ESC.

Currently, the American College of Cardiology Foundation/American Heart Association guidelines recommend a treatment target of <140 mm Hg in individuals 65 to 79 years old, with older patients, those 80 years and older, treated to a target of 140 to 145 mm Hg, if tolerated. The European Society of Hypertension (ESH)/ESC recommend all elderly patients with a baseline systolic blood pressure greater than 160 mm Hg be treated to a target of 140 to 150 mm Hg. For fitter elderly individuals, treating to less than 140 mm Hg can be considered, according to the ESH/ESC.

Need for Further Trials Before Recommendations

In the REGARDS analysis, the researchers attempted to assess the optimal level of blood pressure of 13 948 individuals located in the US stroke belt, those states being North and South Carolina, Georgia, Alabama, Mississippi, Tennessee, Arkansas, and Louisiana. Patients were contacted by telephone every six months to assess stroke events, coronary heart disease events, and all-cause mortality. Medical records were retrieved for suspected strokes and heart-disease hospitalizations and deaths.

Across the three age categories (patients aged 55 to 64 years, 65 to 74 years, and >75 years), the incidence of cardiovascular disease increased with increasing systolic blood pressures, with adults older than 65 years at a significantly increased risk if their blood pressure exceeded 150 mm Hg. Similar trends were observed for the incidence of coronary heart disease, except there was a significantly increased risk in all elderly patients with a blood pressure >150 mm Hg. Stroke incidence increased with increasing blood pressures, but the increased risk was not statistically significant across the three age groups.

Cardiovascular Disease Hazard Ratios by Systolic BP and Age

Age <120 mm Hg 120–129 mm Hg 130–139 mm Hg 140–149 mm Hg >150 mm Hg p linear
Age 65-74 y 1.0 (ref) 1.14 (0.72–1.80) 1.34 (0.85–2.14) 1.44 (0.86–2.41) 2.33 (1.37–3.97) 0.001
Age >75 y 1.0 (ref) 0.80 (0.46–1.38) 0.69 (0.39–1.24) 1.06 (0.58–1.93) 2.18 (1.27–3.76) <0.001

All-Cause Mortality Hazard Ratios by Systolic BP and Age

Age <120 mm Hg 120–129 mm Hg 130–139 mm Hg 140–149 mm Hg >150 mm Hg p linear
Age 55-64 y 1.0 (ref) 1.07 (0.79–1.47) 1.02 (0.73–1.42) 1.50 (1.06–2.14) 1.77 (1.20–2.62) 0.001
Age 65-74 y 1.0 (ref) 1.06 (0.83–1.34) 1.16 (0.91–1.48) 1.35 (1.03–1.75) 1.67 (1.27–2.21) <0.001
Age >75 y 1.0 (ref) 0.86 (0.68–1.08) 0.78 (0.62–0.99) 1.18 (0.91–1.51) 1.00 (0.77–1.29) 0.319

For all-cause mortality, death rates were significantly increased among those aged 55 to 74 years with systolic blood pressures greater than 140 mm Hg. Regarding the very elderly, those older than 75 years of age, all-cause mortality was not significantly affected by blood-pressure levels.

Speaking during the ESC session, Banach said there are approximately one billion individuals worldwide with hypertension, a problem compounded by an aging population. In the US, 34 million adults are older than 65 years of age.

Dr Christi Deaton (University of Manchester, UK) said the conclusions of the hypothesis-generating trial are intriguing, but she pointed out the study was observational only and there are no data on how well these patients were treated once the diagnosis of hypertension was made. With longer follow-up, the relationship between blood-pressure levels and clinical outcomes in the elderly will become clearer as more events are accrued during the REGARDS trial.

"I think we can agree with the investigators and with the clinical guidelines, as they both call for increasing research in older patients before we can set lower blood-pressure targets than are currently recommended in our guidelines," said Deaton.

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