Cardiovascular disease (CVD) is the world’s leading cause of death, accounting for nearly 18 million lives annually, or 33% of the total, well ahead of cancers which are the next highest cause of mortality (17%), according to Our World in Data.
The data are also clear that CVD impacts men and women in different ways, with an overall lower prevalence of coronary disease among women, who typically develop heart problems at older ages – the average age for a first heart attack in men is 65, compared with 72 for women, according to Harvard Medical School.
The picture was more opaque when it came to early onset CVD but recent research by BMC Public Health based on data extracted from China’s Kailuan Study suggests that the older age pattern is repeated with premature heart disease.
“The study highlights gender disparities in all-cause mortality among individuals with early-onset CVD, with men experiencing a higher risk of mortality compared to women.
“Further research is needed to develop sex-specific interventions and strategies to reduce gender-related mortality disparities in early-onset CVD,” said the study, which was led by Qi Zhang from Tangshan Gongren Hospital’s Department of Cardiology.
The Kailuan Study is an ongoing prospective cohort study which started in 2006 and uses data from a community linked to the Kailuan Group coal mining firm, which is based in Tangshan – a coastal city in the North East of China.
There are 11 hospitals providing health care for the Kailuan community and from June 2006 to October 2007, 101,510 participants (81,110 men and 20,400 women; 18–98 years of age) had built up a health record in those medical facilities.
“The study conducts biennial follow-up visits and makes annual checks on cardiovascular as well as all-cause mortality. These conditions enable us to analyse factors influencing mortality following early-onset cardiovascular events in different genders,” said the report.
The team of researchers at Tangshan Gongren Hospital looked at data from 3,087 individuals who developed early onset CVD between June 2006 and December 31, 2020. Premature heart disease was defined as an event which occurred before the age of 55 for men and 65 for women.
Death information was gleaned from the Kailuan social insurance system which provides medical insurance to all the group’s employees.
Men made up 1,984 (70.1%) of the study group and had an average age of 49.5 versus 57 for women. Age wasn’t the only difference between the two groups, with men showing higher diastolic blood pressure and eGFR (glomerular filtration rate; kidney efficiency – a higher reading is better).
More men had received higher education than the female cohort of the study, and they also had higher rates of both drinking and smoking. Interestingly, while smoking was defined as inhaling a single cigarette a day for the previous year, the bar for classifying someone as a drinker was consuming 100ml of 50% proof alcohol a day – or roughly 35 units a week.
Women were more likely to suffer from diabetes and be prescribed antidiabetic medications than men.
The differences in health between the male and female populations in the study was reflected in the period following early onset CVD, with men receiving follow-up care for a median duration of 7.54 years, during which 276 deaths were recorded.
Women had a median follow-up period of 6.45 years, and 105 deaths were recorded during this time. The data showed that adjusting for covariates in the model, men displayed a significantly increased risk of all-cause mortality compared to females.
“Individuals with hemorrhagic strokes exhibited a lower proportion of antiplatelet agent use, and upon their exclusion, men with early-onset CVD continued to manifest a higher risk of all-cause mortality compared to females,” the study said.
The study concluded that the primary outcome variable was all-cause mortality, with a higher incidence in men than women within the early onset CVD group but researchers said that there are multiple factors which cause this and that these vary by gender.
“Smoking and eGFR decline can increase the risk of all-cause mortality in females with early-onset CVD. While achieving blood glucose control and using antiplatelet drugs can reduce the risk of all-cause mortality in males with early-onset CVD,” the study said.
The Tangshan Gongren Hospital research differed from previous findings on gender disparities in all-cause mortality among CVD patients. Previous studies in China and the United States found no gender differences, while Korean researchers concluded there was a higher mortality risk for young women than men.
“In contrast to previous research, our observation pertains to early-onset CVD patients, revealing for the first time that women have a lower risk of mortality than men within the early-onset CVD population,” said the study.
The researchers said that while the underlying data set allowed for what they termed ‘robust’ observation of the relationship between early onset CVD and mortality, it also had a number of limitations.
The paramount issue was the homogenous nature of the Kailuan community which underpinned the study. Other research has shown a pronounced difference in CVD among people from different ethnic groups, such as a 2022 study based on UK Biobank data; a large-scale biomedical database and research resource containing anonymised genetic, lifestyle and health information, and biological samples.
After researchers from the US National Institute of Health crunched the Biobank data, they found that South Asian, but not black African or Caribbean individuals, had a higher risk of CVD compared to white Europeans. Critically the higher risk in South Asians was independent of sociodemographic, lifestyle, environmental, and clinical factors.
Researchers in the Kailuan CVD study explicitly acknowledged this weakness in their results and said that it meant their analysis was unable to account for population and ethnic diversity, and validation of its finding could require its replication across multiple cohorts in various regions.
Despite this weakness, the Kailuan researchers were confident enough in the results to suggest ways that health authorities could use the information about how premature heart disease occurs differently in men and women to structure more effective policy.
“In the early-onset CVD population, the risk of mortality is higher in males than in females. Therefore, future health assessments and explorations of risk factors for early-onset CVD might need to be gender-stratified to achieve maximum cost-effectiveness.”
“Simultaneously, this emphasises the need for gender-specific evaluations in the future construction of health assessment systems and clinical guidelines for individuals with early-onset CVD,” the study concluded.