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High Hematocrit Levels Are Associated with Risk of Cardiovascular Mortality among Middle-Aged Japanese Women: The
Nobuko Takaoka1,2,3, Toshimi Sairenchi1,3,4, Fujiko Irie5
1Department of Public Health, Dokkyo Medical University School of Medicine.
Insights
High hematocrit levels are linked to increased acute myocardial infarction (AMI) mortality risk in younger Japanese women. This association was not observed in men or older women, highlighting a sex-specific risk factor for cardiovascular disease.
Area of Science:
- Cardiovascular epidemiology
- Hematology
- Public health
Background:
- Heart disease and cerebrovascular disease are leading causes of death in Japan.
- Hematocrit, a measure of red blood cell volume, is implicated in cardiovascular diseases.
- The sex-specific relationship between elevated hematocrit and cardiovascular disease risk in Asian populations remains underexplored.
Purpose of the Study:
- To investigate the association between hematocrit levels and the risk of cardiovascular disease mortality, specifically acute myocardial infarction (AMI).
- To examine potential sex differences in this association within a Japanese cohort.
Main Methods:
- Analysis of the Ibaraki Prefectural Health Study, a large community-based cohort of 87,533 individuals (aged 40-79).
- Subjects were followed for a mean of 17.9 years for cause-specific mortality.
- Hematocrit levels were categorized into quintiles, and Cox proportional hazards regression models were used to calculate hazard ratios, adjusting for cardiovascular risk factors.
Main Results:
- A total of 1,207 deaths due to AMI were recorded.
- A significant trend (p=0.020) of increased AMI mortality risk with higher hematocrit levels (Q3-Q5) was observed in women, but not in men (p=0.661).
- This association in women was significant for younger individuals (40-59 years) but not for older individuals (60-79 years).
Conclusions:
- This study is the first to report an association between high hematocrit levels and AMI mortality risk in younger Japanese women.
- The findings suggest a sex-specific and age-specific risk factor for acute myocardial infarction in the Japanese population.
- Further research is warranted to elucidate the mechanisms underlying this observed sex difference.
Abstract:
In Japan, heart disease and cerebrovascular disease were the second and fourth leading cause of death, respectively in 2014. Hematocrit, the ratio of the red blood cells to the total volume of blood is known to play a role in cardiovascular diseases. However, the relationship between elevated hematocrit and the risk of cardiovascular disease based on sex has not been examined in Asian countries. We analyzed data from the Ibaraki Prefectural Health Study, a community-based large cohort study, which included 87,533 individuals, aged 40 to 79 years living in 38 municipalities of the Ibaraki Prefecture, who had completed an annual health checkup in 1993, and were followed until 2013. The hematocrit levels of the subjects were categorized into 5 quintiles (Q1-Q5), and hazard ratios for cause-specific mortality were calculated using the Cox proportional hazards regression models. Age and other cardiovascular risk factors were the covariates in the study. During the follow-up for a mean of 17.9 years, 1,207 deaths (615 men and 592 women) due to acute myocardial infarction (AMI) were reported in this population. The p values for the trend in the Q3-Q5 groups were 0.661 for men and 0.020 for women. Additionally, these values were significant in younger (40 to 59 years) women but not in older (60 to 79 years) women. This study is the first one to demonstrate an association between high hematocrit level and risk of AMI mortality in younger Japanese women, but not in men and older women.
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