Blood Pressure Risk Threshold Is Lower In Women

Women had a lower blood pressure risk threshold than men for heart attack, stroke and heart failure in a large observational study.

"When we look(ed) at patterns of blood pressure measured in people across the lifespan, the range of values - especially among healthy people in younger to middle age - was consistently lower in women compared to men," Dr. Susan Cheng of Cedars-Sinai Medical Center in Los Angeles told Reuters Health by email.

"We conducted this study because if the normal healthy range of blood pressure truly is lower for women than for men, then we should see that risk for adverse cardiovascular events starts to emerge as blood pressure creeps up above a lower threshold for women than for men," she said. "This is indeed what we found."

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"Women are at greater risk for CVD events starting at a lower blood pressure threshold than men - in fact, a blood pressure threshold below what has previously been considered to be 'normal,'" she said.

As reported in Circulation, Dr. Cheng and colleagues analyzed data on more than 27,000 participants (54% women) without baseline CVD in four cohort studies. Age and race distributions were similar between the sexes.

Over 28+/-12 years, 7,424 participants (44% women) developed nonfatal or fatal CVD events: 3,405 had a myocardial infarction (MI); 4,081, heart failure (HF), and 1,901, stroke.

The relationship between CVD and systolic blood pressure (SBP) category - - defined by 10 mm Hg increments from <100 mmHg to 160 mmHg or higher - was calculated using cohort-stratified Cox proportional hazards models accounting for competing risks and adjusting for traditional risk factors, including age, race, body mass index, diastolic BP, antihypertensive therapy, high-density lipoprotein cholesterol level, total cholesterol level, cholesterol-lowering medication, diabetes mellitus, and smoking status.

In sex-pooled analyses, the threshold for incident MI and HF was 120 mmHg to 129 mmHg, and for stroke, 130 to 139 mmHg.

In sex-specific analyses, CVD risk for women began at lower SBP thresholds than for men. Similarly, CVD incidence proportionately increased beginning at a lower range of SBP in women.

Specifically, in multivariable-adjusted analyses, an SBP of 100 to 109 mm Hg relative to SBP <100 mmHg was associated with incident CVD in women; however, in men, the risk was seen at SBP 130 to 139 mmHg.

Importantly, the magnitude of risk seen in men at the higher SBP threshold (hazard ratio, 1.26) was comparable to that seen in women at the lower SBP threshold (HR, 1.25).

Similar sex-specific results were seen for MI and HF - i.e., the MI risk for women with an SBP of 110 to 119 mmHg was comparable to the MI risk for men with an SBP of 160 mmHg or higher; the HF risk for women with an SBP 110 to 119 mmHg was comparable to the HF risk for men with an SBP of 120 to 129 mmHg.

Stroke risk also manifested at sex-specific, albeit higher, thresholds: the risk for women with an SBP of 120 to 129 mmHg was comparable to the risk in men with an SBP of 140 to 149 mmHg.

Dr. Cheng said the team will be studying whether intentionally targeting a lower blood pressure for women offers more protection and clinical benefit.

Dr. Nieca Goldberg; Medical Director of the NYU Women's Heart Program and Senior Advisor, Women's Health Strategy, at NYU Langone Health in New York City told Reuters Health by email, "The article highlights an important consideration when treating hypertension: 'Women are not small men.'"

"The study suggests that the days of the same hypertension treatment guidelines for women and men may be over," said Dr. Goldberg, who was not involved in the study.

That said, she noted, "The research was a metanalysis of four large randomized trials, and to change guidelines, a prospective study would be helpful."

Meanwhile, she suggested, "clinicians should avoid lowering the blood pressure medication dosage in a woman with an SBP in the low 100s who is asymptomatic, as the current study shows that cardiovascular risk starts between SBP levels of 102-109."

"It will likely take time for the medical community to accept this," she acknowledged, "but as additional studies are done and guidelines change and support sex-specific guidelines for hypertension, it will gain greater acceptance."

—Marilynn Larkin

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