Close-up of unrecognizable black woman preparing to check her blood pressure at home with an upper arm blood pressure monitor
CNN  — 

About half of hypertension cases in middle-age and older adults are shared or “concordant” within couples, a new study suggests, meaning if one spouse has high blood pressure, their partner does, too.

Among heterosexual couples in four countries – China, England, India and the United States – the women who were married to men with high blood pressure were more likely to also have hypertension themselves than those whose husbands did not have high blood pressure, according to the study, published Wednesday in the Journal of the American Heart Association. And the men who had wives with hypertension were more likely to have hypertension compared with the men whose wives did not have hypertension.

“Many people know that high blood pressure is common in middle-aged and older adults in the US, England, China, and India. But we were surprised to find out that in these countries, many older couples both have high blood pressure. For instance, in the US, more than 35% of couples who are 50 years or older both have hypertension,” Chihua Li, a post-doctoral fellow at the University of Michigan and an author of the study, said in an email Wednesday.

“Our study is the first one examining concordant hypertension within couples from both high- and middle-income countries using nationally representative data, and therefore providing a cross-national comparison perspective,” Li said. “This is also the largest study on this topic to date.”

The researchers – based at the University of Michigan, Emory University and Columbia University – examined data on 1,086 couples in England; 3,989 couples in the United States; 6,514 couples in China and 22,389 couples in India. The data, which captured a single point in time, was collected in studies and surveys between 2015 and 2019.

The data from the United States and England included adults 50 and older and their spouses, regardless of age. The data from China and India included adults 45 and older and their spouses, regardless of age.

For each spouse, the average of three blood pressure measurements was used to estimate overall systolic blood pressure, the top number in a measurement, and diastolic blood pressure, which is the bottom number. The study considered someone as having hypertension if they had a systolic blood pressure of 140 or greater, a diastolic blood pressure of 90 or greater or a history of high blood pressure diagnosed by a health care provider.

The researchers specifically investigated and compared how many of the couples in the study had “concordant hypertension,” meaning both the husband and wife have high blood pressure.

The researchers found a “high prevalence” of concordant hypertension across all four countries. The data showed that 47.1% of couples in England had concordant hypertension, 37.9% in the United States, 20.8% in China and 19.8% in India.

“These results suggest that around half of all hypertension cases in these populous countries are concordant within couples,” the researchers wrote.

They found that the individual prevalence of hypertension was lower among wives than among husbands across all four countries, but if someone living in China or India had hypertension, it was more likely their spouse did too, compared with the couples living in the United States and England.

“These differences require further investigation and are likely to be multifactorial. They could be attributed to cultural differences between countries,” the researchers wrote, adding that in Asian cultural contexts, couples may be more likely to share the same eating, exercise and lifestyle habits versus in Western cultures, where “individualism” is emphasized.

“High blood pressure is more common in the U.S. and England than in China and India, however, the association between couples’ blood pressure status was stronger in China and India than in the U.S and England. One reason might be cultural. In China and India, there’s a strong belief in sticking together as a family, so couples might influence each other’s health more,” study co-lead author Peiyi Lu, a post-doctoral fellow in epidemiology at Columbia University Mailman School of Public Health, said in a news release Wednesday.

“In collectivist societies in China and India, couples are expected to depend and support each other, emotionally and instrumentally, so health may be more closely entwined,” Lu said.

Overall, the researchers wrote that the high prevalence of concordant hypertension among couples across different countries presents “a promising opportunity” to design ways for couples to manage the disease together, such as screening for high blood pressure together, attending exercise classes together or cooking healthy meals together.

“For couples with hypertension or who have higher risk of hypertension, our study highlights the importance of having health-related conversations with partners and using mutual influence and shared approaches for better hypertension management,” Li wrote in the email. “Couple-centered strategies for diagnosis and management have the potential to have significant impact. More specifically, joint monitoring, exercise programs, and shared lifestyle change can all be actionable.”

This isn’t the first time that spouses’ health status or behaviors have appeared to sometimes mirror each other, said Dr. Bibhu Mohanty, associate professor at the University of South Florida/Tampa General Hospital, who was not involved in the new study.

“A common scenario where we see this is in smoking. If you have a spouse that is trying to quit smoking and you have a partner that is a former smoker who has quit, it makes a huge difference in perspective. Or if they’re both trying to quit together,” Mohanty said.

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“Sometimes, the opposite is also true, which is if you’re trying to get someone to quit smoking and their spouse smokes with them, that’s probably the most challenging scenario, because now it’s really two instances of a bad habit that are reinforcing each other,” he said, adding that hypertension is not a behavior – it’s a medical condition – but many common causes of high blood pressure are behavioral, such as not getting enough regular exercise.

“Similar to smoking, when spouses exercise together or one is in the gym already, it makes it much more likely for the other spouse to either continue exercise routines or initiate them with the husband or wife,” Mohanty said. “So, I think the fact that we’re seeing this now in terms of hypertension – which is not a behavioral thing, per se – is really neat because it shows the possibility that behavioral correlates could have their expression in tangible numbers, whether it’s blood pressure for example or weight could be another example.”