Kunihiko Hirose

Ischemic Stroke Subtypes in a Japanese Population Takashima Stroke Registry, 1988–2004

Background and Purpose— Population-based information on the epidemiology of ischemic stroke (IS) subtypes is scant. In this study, we characterized IS subtypes in terms of incidence, time trend, and risk factor profiles in a community-based population. Methods— We obtained data from the Takashima Stroke Registry on approximately 55 000 residents of Takashima County in central Japan and calculated age-adjusted stroke incidence rates for different IS subtypes. We determined the incidence time trend by calculating the average annual change across years and also compared risk factors between subtypes. Results— There were 1389 first-ever ischemic strokes registered during 1988 to 2004. Lacunar infarction was the most frequent etiology (54.1%) followed by cardioembolic infarction (22.9%). Age-adjusted incidence rates for different IS subtypes were lacunar, 77.1; cardioembolic, 31.5; and nonlacunar, 29.7/105 person-years. The average annual change was not significant for the IS subtypes except for nonlacunar infarction, which showed a decreasing trend. Risk factor analysis showed that patients with lacunar infarctions were younger and less likely to have a history of transient ischemic attack or a drinking habit than patients with nonlacunar infarctions. Conclusion— Lacunar infarct was the most common IS subtype in our population. We found no significant change in the incidence of subtypes during the study, except a decrease in nonlacunar infarction.

The relationship of brachial-ankle pulse wave velocity to future cardiovascular disease events in the general Japanese population: the Takashima Study.

Brachial-ankle pulse wave velocity (baPWV) is a non-invasive measure of arterial stiffness obtained using an automated system. Although baPWVs have been widely used as a non-invasive marker for evaluation of arterial stiffness, evidence for the prognostic value of baPWV in the general population is scarce. In this study, we assessed the association between baPWV and future cardiovascular disease (CVD) incidence in a Japanese population. From 2002 to 2009, baPWV was measured in a total of 4164 men and women without a history of CVD, and they were followed up until the end of 2009 with a median follow-up period of 6.5 years. Hazard ratios (HRs) for CVD incidence according to baPWV levels were calculated using a Cox proportional hazards model adjusted for potential confounding factors, including seated or supine blood pressure (BP). During the follow-up period, we observed 40 incident cases of CVD. In multivariable-adjusted model, baPWV as a continuous variable was not significantly associated with future CVD risk after adjustment for supine BP. However, compared with lower baPWV category (<18 m s−1), higher baPWV (⩾18.0 m s−1) was significantly associated with an increased CVD risk (HR: 2.70, 95% confidence interval: 1.18–6.19). Higher baPWV (⩾18.0 m s−1) would be an independent predictor of future CVD event in the general Japanese population.

Increase of Stroke Incidence after Weekend Regardless of Traditional Risk Factors: Takashima Stroke Registry, Japan; 1988–2003

Background and Purpose: The study purpose was to identify patterns of variation in stroke incidence among days of the week and examine if it is modified by conventional stroke risk factors: hypertension, diabetes, drinking and smoking. Methods: Data were obtained from the Takashima Stroke Registry, which covers a stable population of roughly 55,000 residents of Takashima County in central Japan. A total of 1,773 stroke cases (men: 943 and women: 830) occurred between 1988 and 2003. We divided the days into 3 groups: ‘weekend’, ‘after weekend’ and ‘rest of the week’, and calculated stroke incidence rates and incidence rate ratios. To identify the effect of conventional risk factors on the variation, proportion of differences between observed and expected stroke incidences were considered. Results: The stroke incidence for the after weekend group (250.1 per 100,000 person years, 95% CI: 222.0–278.3) was higher than for the other day groups among men. The after weekend increase was observed mainly among older men aged 65 years or more. Among the stroke subtypes, the incidence for cerebral infarction was highest in the after weekend group (857.2, 95% CI: 730.6–983.8) and was 1.37 times (95% CI: 1.12–1.68) higher than in the rest of the week group. Tendency of after weekend increase was observed regardless of the presence or absence of risk factor history. Conclusions: Week day variation for stroke was observed predominantly among older men regardless of presence and absence of risk factor history. Information about the weekly trend regarding episode of increased stroke incidence can be used as a surrogate predictor for stroke onset and would be helpful in designing more effective insights for preventive strategies.

Morning surge in circadian periodicity of ischaemic stroke is independent of conventional risk factor status: findings from the Takashima Stroke Registry 1990-2003.

Background:  We examined the circadian periodicity of ischaemic stroke (IS) onset and its relationship with conventional risk factors using 14‐year stroke registration data.

Short-term exposure to air pollution and incidence of stroke and acute myocardial infarction in a Japanese population.

Background: Exposure to high levels of air pollution can increase the risk of cardiovascular events. However, there is no clear information in Japan on the effect of pollution on the incidence of stroke and acute myocardial infarction (AMI). Therefore, we investigated the effects of air pollution on the incidence of stroke and AMI in a setting where pollutant levels are rather low. Methods: Data were obtained from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County in central Japan. We applied a time-stratified, bidirectional, case-crossover design to estimate the effects of air pollutants, which included suspended particulate matter (SPM), sulfur dioxide (SO2), nitrogen dioxide (NO2) and photochemical oxidants (Ox). We used the distributed lag model to estimate the effect of pollutant exposure 0-3 days before the day of event onset and controlled for meteorological covariates in all of the models. Results: There were 2,038 first-ever strokes (1,083 men, 955 women) and 429 first-ever AMI cases (281 men, 148 women) during 1988-2004. The mean pollutant levels were as follows: SPM 26.9 µg/m3; SO2 3.9 ppb; NO2 16.0 ppb, and Ox 28.4 ppb. In single-pollutant and two-pollutant models, SO2 was associated with the risk of cerebral hemorrhage. Other stroke subtypes and AMI were not associated with air pollutant levels. Conclusions: We observed an association between SO2 and hemorrhagic stroke; however, we found inconclusive evidence for a short-term effect of air pollution on the incidence of other stroke types and AMI.

Surveillance and measuring trends of stroke in Japan: The Takashima Stroke Registry (1988 – present)

The Takashima Stroke Registry is a disease registration system for stroke established in Japan in 1988. This stroke registry is a population-based, prospective, observational study whose objective is to monitor trends in the incidence and case-fatality of stroke in Japan. Takashima County is located in the rural area of the Shiga prefecture in central Japan, having a stable population of approximately 54,000. It is a farming community with similar cultural values and standards of living throughout the region. The population has remained fairly stable during the 16-year study period. 1750 stroke cases (men 937 and women 813) were registered during 1988–2002. The average ages of the men and women patients were 69.4 and 74.4 years respectively. Stroke diagnostic criteria are established for the Monitoring System for Cardiovascular Disease commissioned by the Ministry of Health and Welfare, Japan. These criteria were based on WHO-MONICA project. Takashima registry system was planned to capture all the cases in the study area by covering all the hospitals of the county. To ensure that eligible patients hospitalized outside the county were not omitted, registration procedures were also conducted at three high-level medical facilities within the Shiga region but outside the county. Due to the high rate of computed tomography use in Japan the identification of stroke cases within the study area is almost complete and stroke diagnosis and classification are accurately recorded.

Is there any circadian variation consequence on acute case fatality of stroke? Takashima Stroke Registry, Japan (1990–2003)

Turin TC, Kita Y, Rumana N, Nakamura Y, Takashima N, Ichikawa M, Sugihara H, Morita Y, Hirose K, Okayama A, Miura K, Ueshima H. Is there any circadian variation consequence on acute case fatality of stroke? Takashima Stroke Registry, Japan (1990–2003). 
Acta Neurol Scand: 2012: 125: 206–212. 
© 2011 John Wiley & Sons A/S.

Ambient air pollutants and acute case-fatality of cerebro-cardiovascular events: Takashima Stroke and AMI Registry, Japan (1988-2004).

Background: Apart from the conventional risk factors, cerebro-cardiovascular disease (CVD) are also reported to be associated with air pollution, thus lowering the level of exposure might contribute in prevention activities to reduce the associated adverse outcomes. Though few studies conducted in Japan have reported on the CVD mortality but none have explored the effect of air pollutant exposure on the acute case-fatality of CVD. We investigated the effects of air pollution exposure on acute case-fatality of stroke and acute myocardial infarction (AMI) in a setting where pollutant levels are rather low. Methods: We leveraged the data from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County located in central Japan. The study period of 6,210 days (16 years, leap years also taken into account) were divided into quartiles of daily average pollutant concentration; suspended particulate matter (SPM), sulfur dioxide (SO2), nitrogen dioxide (NO2), and photochemical oxidants (Ox). The stroke and AMI events were categorized to corresponding quartiles based on the pollution levels of the onset day. To study the effects of air pollutants, we estimated the fatality rate ratio across quartiles of the pollutants where the lowest quartile served as the reference. Results: There were 307 (men: 153 and women: 154) fatal stroke cases within 28 days of onset among the 2,038 first ever stroke during 1988–2004. In the same period, there were 142 (men: 94 and women: 54) fatal AMI cases within 28 days of onset among the 429 first ever AMI events. The mean of the measured pollutant levels were as follows: SPM 26.9 µg/m3, SO2 3.9 ppb, NO2 16.0 ppb, and Ox 28.4 ppb. Among the pollutants, higher levels of NO2 showed increased fatality risk. In multi-pollutant model, the highest quartile of NO2 was associated with 60% higher stroke case-fatality risk in comparison to lowest quartile of NO2. In the fully adjusted model the fatality-rate ratio was 1.65 (95% CI 1.06–2.57). This association was more prominent among stroke subtype of cerebral infarction. Other pollutant levels did not show any association with stroke or AMI case-fatality. Conclusion: We observed association between NO2 levels, an index of traffic related air pollution, with the acute case-fatality of stroke, especially cerebral infarction in our study population. Further studies are needed in different regions to determine the association between ambient air pollutants and acute cardiovascular fatalities.

Diurnal variation in onset of hemorrhagic stroke is independent of risk factor status: Takashima Stroke Registry.

Background: We examined the circadian periodicity of hemorrhagic stroke onset to identify any existing specific pattern and its relationship with conventional stroke risk factors using 14-year stroke registration data. Methods: Data were obtained from the Takashima Stroke Registry, which covers a stable population of approx. 55,000 in Takashima County in central Japan. Out of 499 registered first-ever hemorrhagic stroke events during 1990–2003, there were 429 (186 men, 243 women) events with classifiable onset time. Hemorrhagic stroke incidence was categorized as occurring at night (midnight to 6 a.m.), morning (6 a.m. to noon), afternoon (noon to 6 p.m.) or evening (6 p.m. to midnight). The OR (with 95% CI) of having a stroke in the morning, afternoon or evening were calculated, with night serving as reference. Results: There was significant diurnal variation in hemorrhagic stroke incidence (p < 0.001). The proportion of hemorrhagic strokes was highest in the morning (36.1%, 95% CI: 31.7–40.8) and lowest in the night (11.9%, 95% CI: 9.1–15.3). An excess stroke incidence in the morning was observed in both genders, in subjects <65 years and ≧65 years, and in both intracerebral hemorrhage and subarachnoid hemorrhage. A second surge was also observed during the later part of the day. The higher daytime risk persisted after adjusting for age, gender, and risk factors. Conclusion: In the examination of circadian variation of hemorrhagic stroke onset, a 2-peak temporal distribution was observed, which was independent of conventional risk factors.

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

Background Few comprehensive stroke and acute myocardial infarction registries of long duration exist in Japan to illustrate trends in acute case-fatality of stroke and acute myocardial infarction with greater precision. We examined 17-year case-fatality rates of stroke and acute myocardial infarction using an entire community-monitoring registration system to investigate trends in these rates over time in a Japanese population. Methods Data were obtained from the Takashima Stroke and AMI Registry covering a stable population of approximately 55 000 residents of Takashima County in central Japan. We divided the total observation period of 17 years into four periods, 1989–1992, 1993–1996, 1997–2000, and 2001–2005. We calculated gender, age-specific and age-adjusted acute case-fatality rates (%) of stroke and acute myocardial infarction across these four periods. Results During the study period of 1989–2005, there were 341 fatal cases within 28 days of onset among 2239 first-ever stroke events and 163 fatal cases among 433 first-ever acute myocardial infarction events. The age-adjusted acute case-fatality rate of stroke was 14·9% in men and 15·7% in women. The age-adjusted acute case-fatality rate of acute myocardial infarction was 34·3% in men and 43·3% in women. The age-adjusted acute case-fatality rates of stroke and acute myocardial infarction showed insignificant differences across the four time periods. The average annual change in the acute case-fatality rate of stroke (–0·2%; 95% CI: −2·4–2·1) and acute myocardial infarction (2·7%; 95% CI: −0·7–6·1) did not change significantly across the study years. Conclusions The acute case-fatality rates of stroke and acute myocardial infarction have remained stable from 1989 to 2005 in a rural and semi-urban Japanese population.