Acute Case-Fatality Rates of Stroke and Acute Myocardial Infarction in a Japanese Population: Takashima Stroke and AMI Registry, 1989–2005

Trends in stroke, cardiovascular disease, and medical expenditure under a community-based long-term stroke prevention program

BACKGROUND

Evidence on the effects of preventive measures for noncommunicable disease is urgently needed for low-income and middle-income countries suffering from stroke epidemics along with population aging.

OBJECTIVES

We sought to examine the impact of a community-based stroke prevention program on incidences of stroke and ischemic heart disease, mortality from cardiovascular disease, and medical expenditure.

METHODS

Trends in the incidences of stroke and ischemic heart disease were documented in a Japanese rural community, Kyowa, from 1981 through 2015. Trends in mortality from cardiovascular disease and in medical expenditures were compared between Kyowa and its surrounding municipalities from 1981 through 2004.

RESULTS

In Kyowa, the age-and-sex-adjusted incidences of stroke and of ischemic heart disease decreased by half (from 4.1 to 1.9 and from 1.5 to 0.7 per year/1000 persons, respectively) over the past 35 years. A similar decreasing trend was observed for the age-and-sex-adjusted mortality from cardiovascular disease, and this decreasing trend occurred earlier than that in the surrounding municipalities. The medical expenditures for cardiovascular disease became lower in Kyowa than in the surrounding municipalities over time.

CONCLUSION

Our study's findings suggest that a community-based stroke prevention program augmented the decline in the incidences of stroke and ischemic heart disease, mortality from cardiovascular disease, and attenuated the increase in medical expenditures for cardiovascular disease.

Reduction of Cardiovascular Events and Related Healthcare Expenditures through Achieving Population-Level Targets of Dietary Salt Intake in Japan: A Simulation Model Based on the National Health and Nutrition Survey

Reducing population dietary salt intake is expected to help prevent cardiovascular disease and thus constrain increasing national healthcare expenditures in Japan’s super-aged society. We aimed to estimate the impact of achieving global and national salt-reduction targets (8, <6, and <5 grams/day) on cardiovascular events and national healthcare spending in Japan. Using published data including mean salt intake and systolic blood pressure from the 2019 National Health and Nutrition Survey, we developed a Markov model of a closed cohort of adults aged 40−79 years in 2019 (n = 66,955,000) transitioning among six health states based on the disease course of ischemic heart disease (IHD) and stroke. If mean salt intake were to remain at 2019 levels over 10 years, cumulative incident cases in the cohort would be approximately 2.0 million for IHD and 2.6 million for stroke, costing USD 61.6 billion for IHD and USD 104.6 billion for stroke. Compared with the status quo, reducing mean salt intake towards the targets over 10 years would avert 1−3% of IHD and stroke events and save up to 2% of related national healthcare costs. Attaining dietary salt-reduction goals among adults would yield moderate health economic benefits in Japan.

Japanese Nationwide Study on the Association Between Short-term Exposure to Particulate Matter and Mortality

Background

From around 2012, the use of automated equipment for fine particulate matter (PM_2.5) measurement with equivalence to a reference method has become popular nationwide in Japan. This enabled us to perform a national health effect assessment employing PM_2.5 concentrations based on the standardized measurement method. We evaluated the association between non-accidental mortality and short-term exposure to PM_2.5 and coarse particulate matter (PM), with the latter estimated as the difference between suspended particulate matter and PM_2.5, for the fiscal years 2012–2014.

Methods

This was a time-stratified case-crossover study in 100 highly-populated Japanese cities. Mortality data was obtained from the Ministry of Health, Labour and Welfare. City-specific estimates of PM-mortality association were calculated by applying a conditional logistic regression analysis, and combined with a random-effects meta-analysis.

Results

The respective averages of daily mean concentration were 14.6 µg/m³ for PM_2.5 and 6.4 µg/m³ for coarse PM. A 10 µg/m³ increase in PM_2.5 concentrations for the average of the day of death and the previous day was associated with an increase of 1.3% (95% confidence interval (CI), 0.9–1.6%) in total non-accidental mortality. For cause-specific mortality, PM_2.5 was positively associated with cardiovascular and respiratory mortality. After adjustment for PM_2.5, we observed a 1.4% (95% CI, 0.2–2.6%) increase in total mortality with a 10 µg/m³ increase in coarse PM.

Conclusion

The study revealed that short-term exposure to PM_2.5 had adverse effects on total non-accidental, cardiovascular, and respiratory mortality in Japan. Coarse PM exposure also increased the risk of total mortality.

Diabetes and lifetime risk of stroke and subtypes in an urban middle-aged population

AIMS

Lifetime risk (LTR) is defined as the cumulative probability of developing a disease in one's remaining lifetime from a given index age. The impact of diabetes on the LTR of stroke events in Asians, where stroke incidence is higher than for Westerners, has not been estimated yet. These estimates can be useful for diabetes knowledge translation activities.

METHODS

All participants who were stroke-free at baseline in the Suita Study, a cohort study of cardiovascular diseases in Japan, were included in the study sample. Age, in years, was used as the time-scale. Age-specific incidence rates were calculated using the person-years method within five-year bands. We estimated the sex- and index-age-specific LTR of first-ever stroke accounting for the competing risk of death.

RESULTS

In this cohort study, we followed 5515 participants from 1989 to 2007 for 71,374.23 person-years. At age 40, the LTRs, adjusted for competing risk of death, for all strokes were 15.98% for men without diabetes and 26.64% for men with diabetes. The LTR for stroke was 10.66% higher for men with diabetes than men without diabetes. For women of same index age, the LTR of stroke was 17.29% and 30.72% with diabetes and without diabetes, respectively. The difference in LTR between persons with diabetes and without diabetes was 13.43%. This increased LTR of strokes for persons with diabetes was observed among both men and women across all index ages. Similar results were observed for cerebral infarction stroke subtype.

CONCLUSIONS

In this urban community-based population we observed that diabetes has a significant effect on the residual LTR of stroke for both men and women of middle age. This knowledge can be used to inform public health education and planning.

Body mass index and stroke incidence in Japanese community residents: The Jichi Medical School (JMS) Cohort Study

BACKGROUND

High body mass index (BMI) has been reported as a risk factor for cardiovascular events in Western countries, while low BMI has been reported as a risk factor for cardiovascular death in Asian countries, including Japan. Although stroke is a major cause of death and disability in Japan, few cohort studies have examined the association between BMI and stroke incidence in Japan. This study aimed to examine the association between BMI and stroke incidence using prospective data from Japanese community residents.

METHODS

Data were analyzed from 12,490 participants in the Jichi Medical School Cohort Study. Participants were categorized into five BMI groups: ≤18.5, 18.6-21.9, 22.0-24.9, 25.0-29.9, and ≥30.0 kg/m². Multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using the Cox proportional hazard model. The group with a BMI of 22.0-24.9 kg/m² was used as the reference category.

RESULTS

During mean follow-up of 10.8 years, 395 participants (207 men and 188 women) experienced stroke, including 249 cerebral infarctions and 92 cerebral hemorrhages. Men with a BMI ≤18.5 kg/m² (HR 2.11; 95% CI, 1.17-3.82) and women with a BMI ≥30.0 kg/m² (HR 2.25; 95% CI, 1.28-5.08) were at significantly higher risk for all-stroke. Men with a BMI ≤18.5 kg/m² were at significantly higher risk for cerebral infarction (HR 2.15; 95% CI, 1.07-4.33).

CONCLUSIONS

The association between BMI and stroke incidence observed in this population was different than those previously reported: low BMI was a risk factor for all-stroke and cerebral infarction in men, while high BMI was a risk factor for all-stroke in women.

Hypertension and lifetime risk of stroke

BACKGROUND

The lifetime risk (LTR) articulates the probability of disease in the residual lifetime for an index age. These estimates can be useful for general audience-targeted knowledge translation activities against hypertension. There are only a few reports on lifetime of impact of hypertension on stroke events in Asians in whom stroke incidence is higher than Westerners.

METHODS

The Suita Study, a cohort study of cardiovascular diseases in Japan, was established in 1989. We included all participants who were stroke free at baseline. Age (in years) was used as the time scale. Age-specific incidence rates were calculated with person-year method within 10-year bands. We estimated the sex and index-age specific LTR of first-ever stroke with taking the competing risk of death into account.

RESULTS

We followed 5783 men and women during 1989-2007 for 74 933 person-years. During the follow-up period, 276 (149 men and 127 women) participants had incident stroke. Of them, majority were cerebral infarction; 166 (102 men and 64 women). The LTR of stroke, accounted for competing risk of death, at 45 years of age for men without hypertension was 17.21% and it was 32.79% for hypertensive men. Among the hypertensive patients, participants with stage 2 or greater hypertension had higher LTR of stroke than the participants with stage 1 hypertension. This increased LTR of stroke for hypertensive patients were also observed among women and across all index ages for stroke.

CONCLUSION

In this urban community-based population, we observed that hypertension has significant effect on the residual LTR of stroke among both men and women of middle age, specifically for ischemic stroke.

Long-Term Stroke Risk Due to Partial White-Coat or Masked Hypertension Based on Home and Ambulatory Blood Pressure Measurements: The Ohasama Study

The prognostic significance of white-coat hypertension (WCHT) is controversial, and different findings on self-measured home measurements and 24-h ambulatory monitoring make identifying WCHT difficult. We examined whether individuals with partially or completely defined WCHT, as well as masked hypertension, as determined by different out-of-office blood pressure measurements, have a distinct long-term stroke risk. We followed 1464 participants (31.8% men; mean age, 60.6±10.8 years) in the general population of Ohasama, Japan, for a median of 17.1 years. A first stroke occurred in 212 subjects. Using sustained normal blood pressure (events/n=61/776) as a reference, adjusted hazard ratios for stroke (95% confidence intervals; events/n) were 1.38 (0.82-2.32; 19/137) for complete WCHT (isolated office hypertension), 2.16 (1.36-3.43; 29/117) for partial WCHT (either home or ambulatory normotension with office hypertension), 2.05 (1.24-3.41; 23/100) for complete masked hypertension (both home and ambulatory hypertension with office normotension), 2.08 (1.37-3.16; 38/180) for partial masked hypertension (either home or ambulatory hypertension with office normotension), and 2.46 (1.61-3.77; 42/154) for sustained hypertension. When partial WCHT and partial masked hypertension groups were further divided into participants only with home hypertension and those only with ambulatory hypertension, all subgroups had a significantly higher stroke risk (adjusted hazard ratio ≥1.84, P≤0.04). In conclusion, impacts of partial WCHT as well as partial masked hypertension for long-term stroke risk were comparable to those of complete masked hypertension or sustained hypertension. We need both home and 24-h ambulatory blood pressure measurements to evaluate stroke risk accurately.

Coffee Consumption and Incidence of Subarachnoid Hemorrhage: The Jichi Medical School Cohort Study

Background

Previous studies on the association between coffee consumption and subarachnoid hemorrhage (SAH) have provided inconsistent results. We examine the risk of SAH from coffee consumption in a Japanese population.

Methods

Our analyses were based on the Jichi Medical School Cohort Study, a large-scale population-based prospective cohort study. A total of 9941 participants (3868 men and 6073 women; mean age 55 years) with no history of cardiovascular disease or carcinoma were examined. Participants were asked to choose one of five options to indicate their daily coffee consumption: none, less than 1 cup a day, 1–2 cups a day, 3–4 cups a day, or 5 or more cups a day. The incidence of SAH was assessed independently by a diagnostic committee. Cox proportional hazards models were used to calculate hazard ratios (HRs) and their 95% confidence intervals (CI) after adjustment for age and sex (HR1) and for additional potential confounders (HR2).

Results

During 10.7 years of follow-up, SAH occurred in 47 participants. When compared with the participants who consumed less than 1 cup of coffee a day, the HR of SAH was significantly higher in the group who consumed 5 or more cups a day in both models (HR1 4.49; 95% CI, 1.44–14.00; HR2 3.79; 95% CI, 1.19–12.05).

Conclusions

The present community-based cohort study showed that heavy coffee consumption was associated with an increased incidence of SAH after adjusting for age, sex, and multiple potential cardiovascular confounders.