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Cosmos Study

Mild Hypertension Not Correlated with Increased Likelihood of Stroke or Heart Attack in Patients Aged 75 to 84

June 11, 2024
Dual-Team Study
Team A:Kersten Bartelt, RNEric Barkley
Team B:Blaine Franklin, PT, DPTAlex Piff

Key Findings

  • Patients aged 75 to 84 with elevated blood pressure (systolic 120-129 mmHg and diastolic 70-79 mmHg) did not have an increased likelihood of ischemic stroke or heart attack (myocardial infarction) compared to those within the currently defined normal blood pressure range.
  • However, for patients with systolic blood pressure greater than 140 mmHg or diastolic blood pressure greater than 90 mmHg, the likelihood of ischemic stroke and myocardial infarction is increased.

The American Heart Association defines a normal blood pressure (BP) as a systolic BP below 120 mmHg and a diastolic BP below 80 mmHg.1 A previous study reported an increased risk of stroke among patients whose average systolic BP falls outside of 120 to 130 mmHg.2  We grouped blood pressure readings into standard classifications then added stage 3 hypertension, lower stage 1, and lower stage 2 classifications to capture higher and lower readings for the purpose of this study, as seen in Figure 1.

We studied patients aged 75 to 84 to understand whether current practice guidelines for treating high blood pressure, or hypertension, for those over age 60 also apply to this older population.3 We identified 368,780 patients with no history of ischemic stroke and 374,805 patients with no history of myocardial infarction (MI) with an outpatient visit between October 2021 and December 2021. We adjusted for patient sex, race, ethnicity, social vulnerability index, BMI classification, existing cardiovascular disease diagnoses, history of diabetes, history of hyperlipidemia, smoking history, and frequency of prior care.

Figure 1
Likelihood of Ischemic Stroke by BP Classification
Likelihood of Ischemic Stroke by BP Classification
Figure 1. The likelihood of a patient experiencing an ischemic stroke by their BP classification.

We found that patients with blood pressures in the hypertensive range (systolic BP greater than 130 mmHg or diastolic BP greater than 80 mmHg) had an increased likelihood of ischemic stroke with an 11% increase for stage 1, a 21% increase for stage 2, and a 38% for stage 3 compared to those with normal blood pressure. However, those in the elevated or lower-than-normal BP categories are no more likely to experience an ischemic stroke. This indicates that for patients aged 75 and 84 having a blood pressure in the elevated BP category does not increase the likelihood of stroke.

Next, we explored the relationship between BP and the likelihood of experiencing an MI. We found that patients with stage 2 or stage 3 hypertension were slightly more likely to have an MI compared to those with normal blood pressure, though the increase for stage 3 was not statistically significant. Patients with blood pressures in the elevated, lower stage 1, or lower stage 2 categories were no more likely than a patient with a normal BP to have an MI.

Figure 2
Likelihood of Myocardial Infarction by BP Classification
Likelihood of Myocardial Infarction by BP Classification
Figure 2. The likelihood of a patient experiencing a myocardial infarction by their BP classification.

These data come from Cosmos, a dataset created in collaboration with a community of Epic health systems representing more than 246 million patient records from 1,400 hospitals and more than 32,500 clinics from all 50 states and Lebanon. This study was completed by two teams that worked independently, each composed of a clinician and research scientists. The two teams came to similar conclusions. Graphics by Brian Olson. 

References

  1. Understanding blood pressure readings. www.heart.org. https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings. Accessed April 12, 2024.
  2. Fan F, Yuan Z, Qin X, et al. Optimal systolic blood pressure levels for primary prevention of stroke in general hypertensive adults: Findings from the CSPPT (China Stroke Primary Prevention Trial). Hypertension. 2017;69(4):697-704. doi:10.1161/hypertensionaha.116.08499
  3. Qaseem A, Wilt TJ, Rich R, et al. Pharmacologic treatment of hypertension in adults aged 60 years or older to higher versus lower blood pressure targets: A clinical practice guideline from the American college of physicians and the American academy of family physicians. Ann Intern Med. 2017;166(6):430. doi:10.7326/m16-1785