How low is too low? Study highlights serious risks for intensive blood pressure control

August 24, 2018

Kaiser Permanente research published today in the American Journal of Preventive Medicine found if patients with hypertension taking prescribed medications experience unusually low blood pressures -- systolic blood pressure under 110mmHg -- they are twice as likely to experience a fall or faint as patients whose treated blood pressure remains 110mmHg and above.

This research is timely because late last year the American Heart Association and the American College of Cardiology lowered its definition of high blood pressure from a systolic blood pressure of at least 140 to a systolic of at least 130, said the study's lead author John J. Sim, MD, a nephrologist with the Kaiser Permanente Los Angeles Medical Center.

"Efforts to reduce blood pressures for patients with hypertension are an important factor in reducing the risk of heart attack and stroke," Dr. Sim said. "But our study shows that attaining a lower blood pressure could create to a subpopulation of patients whose blood pressures may go too low, which can pose risk for serious falls and fainting."

To determine the effects of blood pressure reduction among hypertension on patients, Dr. Sim and a team of researchers studied the electronic health records of more than 475,000 Kaiser Permanente patients in Southern California who were prescribed medication to treat hypertension. Over a one-year period, both mean and minimum systolic blood pressure readings of less than 110 mmHg were associated with higher rates of serious falls and fainting that resulted in emergency department visits or inpatient encounters.

Among the patients with treated blood pressure:

27 percent had a systolic blood pressure under 110mmHg during at least one visit

3 percent of patients had an average systolic pressure reading of less than 110mmHg over the one-year study period

Patients with a single episode of systolic pressure lower than or equal to 110mmHg during the one-year period were twice as likely to experience a serious fall or faint

Patients who had an average systolic blood pressure lower than 110mmHg over the one-year study period had a 50 percent greater risk of serious falls and fainting than those who had an average systolic blood pressure higher than 110mmHg

"Physicians considering lower blood pressure targets for their patients should weigh the risks and benefits of aggressive blood pressure lowering on an individual basis, especially in older patients," said Dr. Sim.

He noted that older patients are more likely to have acute reductions in blood pressure, such as orthostatic hypotension, which is when a patient's blood pressure drops substantially when they stand or get upright, and have slower reflexes to compensate and normalize their blood pressure. They also are more susceptible to side effects of low blood pressure, he said.

Some characteristics physicians should watch out for before considering lowering a patient's blood pressure are acute illness, blood pressure variation throughout the day, and orthostatic hypotension, Dr. Sim said.
-end-
This study was supported by the Kaiser Permanente Southern California Clinician Investigator Program.

Other authors on this study include Hui Zhou, PhD, Rong Wei, MS, Steven J. Jacobsen, MD, PhD, and Kristi Reynolds, PhD, of the Kaiser Permanente Southern California Department of Research & Evaluation, Pasadena, California; Simran K. Bhandari, MD, Kaiser Permanente Los Angeles Medical Center; Jeffrey W. Brettler, MD, Jocelyn Tran-Nguyen, PharmD, and Joel Handler, MD, Regional Hypertension Program, Kaiser Permanente Southern California, Pasadena; and Daichi Shimbo, MD, Department of Medicine, Columbia University Medical Center, New York.

About the Kaiser Permanente Southern California Department of Research & Evaluation

The Department of Research & Evaluation conducts high-quality, innovative research into disease etiology, prevention, treatment and care delivery. Investigators conduct epidemiologic research, health services research, biostatistics research, and behavioral research as well as clinical trials. Major areas of study include chronic disease, infectious disease, cancer, drug safety and effectiveness, and maternal and child health. Headquartered in Pasadena, California, the department focuses on translating research to practice quickly to benefit the health and lives of Kaiser Permanente Southern California members and the general public. Visit kp.org/research.

About Kaiser Permanente

Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America's leading health care providers and not-for-profit health plans. Founded in 1945, Kaiser Permanente has a mission to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve more than 12.2 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal Permanente Medical Group physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to: kp.org/share.

Kaiser Permanente

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