Incidence Rate Of Subarachnoid Hemorrhage Research Articles

Global burden of stroke in adolescents and young adults (aged 15–39 years) from 1990 to 2019: a comprehensive trend analysis based on the global burden of disease study 2019

SummaryIntroductionThe incidence of stroke is rising among individuals aged 15–39. Insufficient research targeting this age group hampers the development of effective strategies. This study analyzes data from the Global Burden of Disease Study 2019 (GBD 2019) to examine trends from 1990 to 2019 and propose future interventions.MethodsData on ischemic strokes, intracerebral hemorrhage, and subarachnoid hemorrhage from 1990 to 2019 was collected from the Global Health Data Exchange (GHDx) platform. We used the Annual Average Percentage Change (AAPC) to assess global trends in incidence, prevalence, Disability-Adjusted Life Years (DALYs), and mortality rates across various stroke categories. Joinpoint models identified significant years of trend inflection. Trend analyses were segmented by age, gender, and Sociodemographic Index (SDI).FindingsFrom 1990 to 2019, the global incidence of ischemic stroke within the adolescents and young adults (AYAs) cohort declined from 1990 to 1999, further decreased from 2000 to 2009, and then increased from 2010 to 2019. The overall AAPC p-value showed no significant difference. Mortality rates for ischemic strokes were consistently reduced during this period. The overall incidence rate of intracerebral hemorrhage has exhibited a downward trend. Meanwhile, the incidence rate of subarachnoid hemorrhage decreased from 1990 to 2009, yet saw a resurgence from 2010 to 2019. Male ischemic stroke incidence grew more than female incidence, but both absolute incidence and rates were higher for females. Differences in SDI levels were observed, with the fastest increase in incidence occurring in low-middle SDI regions, followed by high SDI regions, and the smallest increase in low SDI regions. Conversely, the most rapid decline was noted in high-middle SDI regions, with no significant change observed in middle SDI regions.ConclusionA concerning trend of increasing ischemic stroke incidence, DALYs, and prevalence rates has emerged in the global 15–39 age group, especially among those aged 30–39. This increase is evident across regions with varying SDI classifications. To combat this alarming trend among adolescents and young adults, enhancing preventive efforts, promoting healthier lifestyles, strengthening the healthcare system’s responsiveness, and maintaining vigilant epidemiological monitoring is essential.

Recent Declining Trend of Incidence Rate of Subarachnoid Hemorrhage in Shimane, Japan: The Japan Incidence of Subarachnoid Hemorrhage (JIS) Study.

The "Izumo Study" revealed the incidence rate of subarachnoid hemorrhage (SAH) in Izumo City, Shimane Prefecture, Japan, from 1980 to 1998. However, no study has been published regarding the incidence of SAH in Shimane Prefecture after 1998. Most studies reporting the incidence of SAH in Japan have been conducted before 2000, although a few have been reported after 2000. This study aimed to assess the estimated age-adjusted incidence rate (AAIR) of SAH in Shimane Prefecture after 1998, following the Izumo Study. A retrospective study was conducted to identify the estimated AAIR of SAH in Shimane Prefecture, using the age-adjusted SAH mortality rate for this population from 1999 to 2017 and assuming that the case-fatality rate of SAH decreased by 0.7% annually from 45% in 1999 to 32.4% in 2017. We used linear regression analysis for trend to the estimated AAIR of SAH. Sensitivity analyses were also conducted by various case-fatality rates of SAH using assuming case-fatality rate based on previous reports. The estimated AAIR of SAH in Shimane Prefecture declined from 33.6 (95% confidence interval [CI]: 29.7-37.9) per 100,000 person-years in 1999, by 26.5%, to 24.7 (95% CI: 21.4-28.5) in 2017 (p < 0.01, r = 0.58). Declining trend of incidence rate of SAH in Shimane Prefecture from 1999 to 2017 was confirmed in this study.

Population-Based Incidence Rates of Subarachnoid Hemorrhage in Japan: The Shiga Stroke and Heart Attack Registry.

Population-Based Incidence Rates of Subarachnoid Hemorrhage in Japan: The Shiga Stroke and Heart Attack Registry.

Letter regarding article ‘Abdominal aortic aneurysm is associated with subarachnoid hemorrhage’

We read with great interest the recent article by Wilkinson et al 1 published in the Journal of NeuroInterventional Surgery in November 2020, in which the authors compared the incidence...

Abstract WMP92: High Nationwide Incidence and Decline Trend of Subarachnoid Hemorrhage From Register-based Study in Japan

Background and Purpose: There has never been a report of the nationwide incidence rate and the recent trend of subarachnoid hemorrhage (SAH) in Japan. This study aimed to clarify the age-standardized nationwide incidence rate and recent trend of SAH in Japan and reasons for recent changes in this trend. Methods: We compiled data from the Japan Neurosurgical Society and records from the Ministry of Health, Labor, and Welfare in Japan. We reviewed the age-standardized mortality rate and estimated crude incidence rate of SAH including the 95% confidence interval (CI) from 2002 to 2017. The trend in treatment numbers of unruptured cerebral aneurysms (UCAs), ruptured cerebral aneurysms, the estimated treatment rate of UCAs with 95% CI, and the prevalence of hypertension, current smoking and use of cholesterol-lowering drugs were assessed. Results: Based on the 2010 population as a reference, the age-standardized nationwide SAH mortality rate significantly declined from 13.91 (95%CI:13.90-13.91) to 8.12 (8.12-8.13) by 41.7% per 100,000 person-years from 2002 through 2017. The estimated crude incidence rate of SAH excluding conservative survivors per 100,000 also showed a significant decline from 25.41 (25.40-25.42) to 21.35 (21.34-21.36) by 16.0 % and from 23.89 (23.88-23.89) to 20.05 (20.04-20.05) by 16.1% , if the in-hospital mortality was 10% and 20%, respectively. The prevalence of hypertension and current smoking declined significantly (p&lt;0.05) and use of cholesterol-lowering drugs increased significantly (p&lt;0.05) during the same period. Conclusions: The nationwide incidence rate of SAH in Japan was higher than in other countries. However, the declining trend of SAH was shown in this study. Improving lifestyle might contribute to reducing the incidence of SAH in Japan.

Abstract WP228: Seasonal Variation of Stroke Subtypes Incidence in Population-based Study in Shiga Prefecture, Japan

Introducution: Incidence rates of stroke have been shown to have seasonal variations. However, current evidence is limited for Japanese populations. The aim of this study was to investigate seasonal variation in incidence of stroke and its subtypes in a general population of 1.4 million Japanese. Methods: Shiga Stroke Registry is an ongoing population-based registry of stroke, which covers approximately 1.4 million residents of the Shiga prefecture in central Japan (located central part of Honshu Island). There is an integrated surveillance system involving the registration of cases among a network of all acute care hospitals with neurology/neurosurgery facilities and smaller hospitals with rehabilitation facilities. A total of 2,753 adult (18 years) cases of stroke (1838 ischemic stroke,713 intracerebral hemorrhage,196 subarachnoid hemorrhage and 6 other/unclassified), who were registered in 2011, were included in the present analysis. Incidence of stroke in each month of the year was estimated using 2011 vital statistics by a Poisson regression model with adjustment for age and gender. Results: The age- and gender-adjusted incidence rates of total stroke were 180, 176, 177, 162, 163, 149, 134, 128, 133, 152, 144, 177per 100,000 person-years from January to December, respectively. Incidence rates in summer were lower in summer (July to September) than those in winter (December to February) or spring (March to May). Similar patterns were also observed for both ischemic stroke and intracerebral hemorrhage although seasonal variation was much more remarkable for intracerebral hemorrhage.There were no clear differences between summer and winter for incidence rates of subarachnoid hemorrhage. Conlusions: Incidence rates of ischemic stroke and intracerebral hemorrhage seem to be high in winter and spring based on large-scale population-based stroke registry in Japan.

Monthly variations in aneurysmal subarachnoid hemorrhage incidence and mortality: Correlation with weather and pollution.

Background and purposeAlthough the effect of weather and air pollution on the occurrence of subarachnoid hemorrhage (SAH) has been investigated, results have remained inconsistent. The present study aimed to determine the seasonality of aneurysmal subarachnoid hemorrhage occurrence and mortality.MethodsWe used the National Inpatient Sample database to evaluate the effect of meteorological factors and air pollutants on patients with subarachnoid hemorrhage in Korea between 2011 and 2014. Monthly variations in SAH occurrence and mortality were analyzed using locally weighted scatter plot smoothing curves. Multivariate Poisson generalized linear regression models were used to evaluate potential independent meteorological and pollutant variables associated with SAH occurrence and mortality.ResultsIn total, 21,407 patients who underwent clip or coil treatment owing to aneurysmal SAH in Korea from January 1, 2011, to December 31, 2014, were included. The crude incidence rate of SAH in Korea was 10.5 per 100,000 people per year. An approximately 0.5% lower risk of SAH was observed per 1°C increase in mean monthly temperature (relative risk, 0.995; 95% confidence interval [CI], 0.992–0.997; p < 0.001), while an approximately 2.3% higher risk of SAH was observed per 1°C increase in mean monthly diurnal temperature.ConclusionsWe showed distinct patterns of seasonal and monthly variation in the occurrence and mortality of SAH. Our findings suggest that meteorological factors may play an important role in monthly variations in the occurrence of aneurysmal SAH.

Subarachnoid Hemorrhage in Germany Between 2010 and 2013: Estimated Incidence Rates Based on a Nationwide Hospital Discharge Registry.

Nordic countries are the primary source for nationwide data on the incidence of subarachnoid hemorrhage (SAH). Reliable estimates of national incidence rates of SAH in other countries are lacking, yet studies from Nordic countries with exceptional incidence rates are sometimes disregarded because of concerns regarding external validity. Autopsies are rarely performed for sudden deaths; therefore, estimates of the SAH incidence commonly reflect the hospital discharge rates. Our aim was to estimate the nationwide incidence of nontraumatic SAH in Germany using a national hospital discharge register. The German federal statistical office provided the number of patients discharged from all German hospitals between 2010 and 2013 with the primary diagnosis of nontraumatic SAH (ICD code I60.0-I60.9) and corresponding age distribution. Age-standardized attack rates of nontraumatic SAH were calculated using the 2011 German demographic distribution. Between 2010 and 2013, the overall age-standardized incidence rate of nontraumatic SAH was 11.3 per 100,000 person-years, and it reached a maximum of 22.1 per 100,000 person-years in the oldest age group. The absolute number of SAHs was highest in the 50-55-year age group. The distribution of intracranial aneurysms displayed a propensity toward the posterior circulation with advancing age (P < 0.001), although in absolute numbers SAH originated mostly from the anterior circulation. Our estimate of the German nationwide attack rate suggests that the incidence of nontraumatic SAH is more homogeneous than previously assumed. Rejecting the external validity of studies from countries believed to display an exceptional incidence rates may therefore not be justified.

Incidence of subarachnoid hemorrhage is decreasing together with decreasing smoking rates.

To determine the nationwide incidence of subarachnoid hemorrhage (SAH) and report nationwide changes in smoking rates between 1998 and 2012 in Finland. In this register-based study, we utilized the nationwide Causes of Death Register and Hospital Discharge Register in identifying SAH events between 1998 and 2012. Population statistics in Finland, which were obtained through a database of Statistics Finland, were used to calculate crude annual incidence rates of SAH. For the direct age standardization of crude incidence rates, we used the European Standard Population (ESP) 2013. Data on changes in nationwide smoking rates between 1998 and 2012 were extracted from a database of the National Institute for Health and Welfare. For the total of 79,083,579 cumulative person-years, we identified 6,885 people with SAH. Sudden deaths from SAH away from hospitals or in emergency rooms accounted for 1,771 (26%) of the events. Crude nationwide annual incidence rates varied between 6.2 and 10.0 per 100,000 persons, and increased by age particularly in women. Among 70- to 75-year-old women, the incidence of SAH was highest (22.5 per 100,000 persons). The 3-year average of ESP standardized incidence decreased 24% from 11.7 in 1998-2000 to 8.9 per 100,000 persons in 2010-2012. Daily smoking decreased 30% between 1998 and 2012. The incidence of SAH seems to be decreasing. This tendency may be coupled with changes in smoking rates. The incidence of SAH in Finland is similar to other Nordic countries.

Risk Factors and Their Combined Effects on the Incidence Rate of Subarachnoid Hemorrhage – A Population-Based Cohort Study

BackgroundProspective studies on the risk factors for subarachnoid hemorrhage (SAH) are limited. Moreover, the effect of risk factors on the incidence rates of SAH is not well known about.AimsIn this study, we aimed to identify risk factors for SAH and characterize subgroups in a population with a high incidence of SAH.MethodsAfter recording multiple potential risk factors for SAH at the time of enrolment, first ever SAH events between 1972 and 2009 were recorded through the nationwide Causes of Death Register and Hospital Discharge Register for the population-based cohort of 64 349 participants, who participated in the National FINRISK Study between 1972 and 2007 in Finland.ResultsDuring the follow-up time of 1.26 million person-years (median 17.9 years, range 0 to 37.9 years), 437 persons experienced fatal or non-fatal SAH. Crude SAH incidence was 34.8 (95% confidence interval: 31.7–38.2) per 100 000 person-years among ≥25-year-old persons. Female sex, high blood pressure values and current smoking were confirmed as risk factors for SAH. Previous myocardial infarction, history of premature stroke (any kind) in mother and elevated cholesterol levels in men were identified as new risk factors for SAH. Depending on the combination of risk factors, SAH incidence varied between 8 and 171 per 100 000 person-years.ConclusionsNew and previously reported risk factors appear to have a much stronger association with the incidence of SAH than is ordinarily seen in cardiovascular diseases. Risk factor assessments may facilitate the identification of high-risk persons who should be the focus of preventive interventions.

Abstract TP187: Risk of Subarachnoid Hemorrhage among Patients Infected with Human Immunodeficiency Virus

Background: In the current literature, subarachnoid hemorrhage data among patients with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) is limited to case reports. Objective: To compare the incidence and relative risk of subarachnoid hemorrhage (SAH) in patients with AIDS to those who are HIV negative, on a national level. Method: The Nationwide Inpatient Sample (NIS 2002-2010) was used to identify and all patients presenting with the primary diagnosis of SAH in the United States between 2002 and 2009. Among this cohort, we identified the patients with HIV/AIDS and those who were HIV negative and further stratified them based on gender and age: 13-24 years, 25-34 years, 35-44 years, 45-54 years and 55+ years. We obtained the number of people living with AIDS in the United States population from the Centers for Disease Control and Prevention (CDC) for 2002 according to the same age groups. Using the 2000 United States census information we identified the number of people in the general population and subtracted the AIDS cases within the respective age group. The relative risk of developing a SAH in patients with AIDS versus the HIV negative patients was also obtained between 2002 and 2009. Result: The age adjusted annual incidence of SAH was 62.3 per 100,000 and 20.2 per 100,000 among HIV/AIDS positive persons and HIV negative persons. The age adjusted annual relative risk for SAH among the HIV/AIDS positive persons was 3 (95% confidence interval 2.4 to 3.8). HIV positive women had higher incidence of SAH when compared to HIV positive males except for the 13-24 year old group. The SAH rate ratio decreased with each increasing decade when compared with HIV negative patients: 13-24 years (25), 25-34 years (8.6), 35-44 years (3), 45-54 years (2.4) and 55+ years (1.6). The 7 year incidence rate of SAH in HIV positive men between 13-24 years was 29 times more than in HIV negative men; similarly, the incidence of SAH among HIV positive women was 18 times that of HIV negative women. Conclusion: HIV/AIDS positive persons, particular young individuals, appear to have an increased risk of developing SAH.

Trends in the incidence of subarachnoid hemorrhage in Akita Prefecture, Japan

The incidence of subarachnoid hemorrhage (SAH) in Japan has been reported to be among the highest in the world. The aim of this study was to analyze the incidence of SAH and its trends in Akita Prefecture, Japan. The incidence rate of SAH between January 1, 1989, and December 31, 1998, was investigated using the prospective Akita Stroke Register. Computed tomography scans were obtained in all suspected cases of SAH. During the study period, 3257 patients with their first SAH were registered. The crude annual incidence rates of SAH in men, women, and both sexes were 20, 33, and 27 per 100,000 population per year, respectively. Age-standardized incidence rates remained stable. Crude incidence rates in women increased. In men the incidence reached a plateau after 55 years of age; in women it peaked in the eighth decade of life. The 28-day case fatality rate was 26.7%, without significant changes. Two diurnal peaks were observed: one at 7 a.m. and another at 5 p.m. The incidence was lowest in summer and highest in spring, in both sexes. The incidence of SAH in patients in Akita Prefecture is similar to that reported in other Japanese studies. The age-standardized incidence rates are stable. The increasing crude incidence in women is probably attributable to the aging of the Japanese population.

Regional variation in hospitalization for stroke among Asians/Pacific Islanders in the United States: a nationwide retrospective cohort study

BackgroundIn Asia, stroke incidence varies dramatically from country to country. Little is known about stroke incidence in Asians/Pacific Islanders in the US, where regional heterogeneity in Asian/Pacific Islander sub-populations is great. We sought to characterize both the national and regional incidences of first and recurrent hospitalized acute ischemic stroke, subarachnoid hemorrhage, and intracerebral hemorrhage in Asians/Pacific Islanders compared to non-Hispanic whites.MethodsWe used the National Inpatient Sample of the 1997 Healthcare Cost and Utilization Project. It is a 20% stratified sample of hospitalizations to nonfederal hospitals in the US. National and regional projections were made using sampling weights specific for patients and hospitals. We identified stroke subtypes using previously validated ICD-9 codes. Age-adjusted incidence rates were calculated using the direct method with the US population in 2000 as the standard.ResultsThere were 169,386 stroke hospitalizations in the database. Nationally, compared to whites, Asians/Pacific Islanders were more likely to have subarachnoid hemorrhage (incidence rate ratio {RR} female: 1.53, 95% CI 1.41–1.65; male RR: 1.13, 95% CI 1.00–1.27) and intracerebral hemorrhage (female RR 1.29, 95% CI 1.22–1.36; male RR: 1.58, 95% CI 1.50–1.67). However, when examined by geographic regions, Asians/Pacific Islanders had higher incidence rates of subarachnoid hemorrhage and intracerebral hemorrhage predominantly in the West, and lower rates of stroke elsewhere.ConclusionStroke incidence varies 3-fold among Asians/Pacific Islanders residing in different US regions. Geographic variation is less dramatic in whites. Whether genetic or cultural differences are responsible for dramatic heterogeneity among Asian/Pacific Islander populations is unclear and deserves further study.

Declining mortality from subarachnoid hemorrhage: changes in incidence and case fatality from 1985 through 2000.

Northern Sweden has one of the highest incidence rates of subarachnoid hemorrhage (SAH) among the populations covered by the WHO MONICA (Monitoring of Trends and Determinants in Cardiovascular Disease) Project, approximately twice as high as in the other populations in Europe. In this study, trends in incidence, 28-day case fatality (CF), and mortality in SAH were followed over a 16-year period. Since 1985, all SAHs in northern Sweden among patients 25 to 74 years old have been validated using strict MONICA criteria. From 1985 through 2000, 392 men and 592 women had SAH. During 3 years, 1997 to 1999, SAH among those aged 75 and older were also included. The total incidence among those 25 years and older was 13.3 per 100 000 in men and 24.4 per 100 000 in women. During the 16 years of observation, age standardized incidence in the group aged 25 to 74 years decreased significantly in men (P for trend <0.0001) but remained essentially unchanged in women (P for trend=0.64). The 28-day CF for all years was 36.5% in men, with no significant trend (P=0.7). In women, average CF was 35%, with a significant decline (P=0.003). The annual mortality decreased significantly in both sexes (by 3.87 [95% CI+/-2.75 percentage points] in men and 3.97 [95% CI+/-2.29] in women). The decline in SAH mortality has different explanations in men (declining incidence) and in women (declining CF).

Treatment options of unruptured intracranial aneurysms.

Aneurysmal subarachnoid hemorrhage (SAH), despite improvements in surgical and medical treatment, is still a serious disease with high rates of case fatality (40% to 50%) and morbidity.1–3 Incidence rates of SAH have not changed during the CT era, and outcome of SAH has only modestly improved during the past few decades. Outcome is still determined mainly by severity of initial bleeding or early rebleeding.1–4 It seems that identification of preventive treatment methods for aneurysm rupture and of modifiable risk factors for SAH are important as means to influence incidence and outcome of this serious disease. Unruptured aneurysms, when incidentally discovered or found in connection with diagnosis of ruptured aneurysm (multiple aneurysm cases), have been operated on for 2 to 3 decades in western countries. In this way, the high case fatality and morbidity associated with a possible severe initial bleed can be eliminated by preventive surgical intervention. However, the natural history as well as risks of surgery of unruptured intracranial aneurysms are poorly known as are the risk factors for rupture because of lack of studies with sufficient number of patients and follow-up years. The Table shows cohorts of largest studies of rupture risk of unruptured intracranial aneurysms.4–8 The recently published prospective part of The International Study of Unruptured Intracranial Aneurysms (ISUIA; patient enrollment in 61 centers between 1991 and 1998)5 shows somewhat different results as compared with those of the retrospective part of ISUIA (in 53 centers between 1970 and 1991).7 In the prospective study,5 overall incidence of aneurysm rupture was higher (0.8% versus 0.3% per year); risk for rupture of vertebrobasilar aneurysms was lower (relative risk 2.3 versus 5.1 to 13.8 as compared with other aneurysms); mean follow-up time per patient was shorter (3.9 versus 8.3 years); there was a lower limit …

一山間地域におけるくも膜下出血の診療

From January 1997 to December 2001, patients with subarachnoid hemorrhage (SAH) among 14,008 residents in an isolated mountainous area; Oguni and Minamioguni towns in Kumamoto Prefecture, were evaluated. The subjects were patients being treated at Oguni Municipal Hospital. Over a period of 5 years, 19 patients were found to be suffering from SAH in this area, 3 of whom were visitors (residing outside this area). The annual incidence rate of SAH in this area was calculated as 22.9 per 100,000. The sex ratio (men:women) was 4:12. The average age was 67.9 years; 65.0 years for men and 68.8 years for women. Eleven patients were older than 65, and constituted 68.8% of the subjects. The risk factors of SAH were recognized, and both hypertension and smoking constituted 31.6%. Alcohol was 21.1% and hyperlipemia was 15.8%. In 13 clipping operated cases excluding 1 test craniotomy, Hunt & Kosnik's Grades at admission were G.I: 2, G.II: 5, G.III: 3, G.IV: 2 and G.V: 1, and Fisher's Groups were G.I: 0, G.II: 8, G.III: 3 and G.IV: 2. The sites of 16 operated aneurysms were internal carotid-posterior communicating artery (IC-PC): 2, anterior communicating artery (A Co.A): 4, middle cerebral artery (MCA): 10 and vertebral artery-basilan artery (VA-BA): 0. The aneurysmal size were < 5 mm: 5, 6-10 mm: 9 and 11 mm < :2 (average 7.6 mm, 2-15 mm). The results were evaluated at discharge, excluding 1 SAH of unknown etiology. 9 were good, 2 were dependent and 7 including 5 non-operative cases had died. We were satisfied with these results, because we were treating older patients. Although we attempted the clipping operation using only a three dimensional computed tomographic angiograply (3D-CTA; X-Vision GX (TOSHIBA) & X-Tension), we had no problem, except for 1 test craniotomy. 3D-CTA was useful during the clipping operation in the small hospital, especially, in regard to cost.

Trends in Incidence and Case Fatality Rates of Aneurysmal Subarachnoid Hemorrhage in Izumo City, Japan, Between 1980–1989 and 1990–1998

With aging of the population, the profile of subarachnoid hemorrhage (SAH) is likely to change; however, evaluation of long-term trends for incidence and case fatality rates of SAH is still limited. We compared the incidence and case fatality rates of aneurysmal SAH during the 9-year period 1990-1998 with those during the 10-year period 1980-1989 in Izumo City, Japan. During 1980-1989 and 1990-1998, we diagnosed 170 and 188 patients as having aneurysmal SAH, respectively. The percentage of very elderly patients aged >/=80 years increased from 5% (8 patients) during 1980-1989 to 18% (33 patients) during 1990-1998 (P<0.001). The age-specific incidence rate of SAH has a tendency to increase with increasing age. The crude and the age- and sex-adjusted incidence rates using the 1995 population statistics for Japan were 21 and 23 per 100 000/y for all ages during 1980-1989 and 25 and 23 per 100 000/y during 1990-1998, respectively. The 3-month case fatality rate of patients aged </=79 years decreased from 38% during 1980-1989 to 26% during 1990-1998 (P=0.021), whereas the case fatality rates in patients aged >/=80 years were very high (63% and 79%, respectively) regardless of study periods. Consequently, the overall case fatality rates for patients with SAH were similar for the 2 study periods (39% and 36%). The age- and sex-adjusted incidence rates of aneurysmal SAH were stable over the 19-year period since 1980 and, despite improvement of outcome in patients aged </=79 years, the overall case fatality rate was not lower because the improvements were counterbalanced by increasing numbers of very elderly patients

What are the actual incidence and mortality rates of subarachnoid hemorrhage?

From 1987-92 in Izumo City, Japan, we diagnosed 123 patients as having subarachnoid hemorrhage (SAH) by computed tomography, autopsy, or surgery (proven SAH); the crude incidence rate was 25/100,000/year for all ages. However, to estimate the actual incidence and mortality rates, we should take into account the decedents who died without confirmation by these methods but were presumed to have died of SAH. From 1987-92, we reviewed all of 3562 death certificates for the city of Izumo (population 82,679), and calculated the incidence and mortality rates of SAH by combining proven and possible SAH. We diagnosed 36 patients as having possible SAH on death certificates. When adding these 36 patients to the 123 with proven SAH, the crude and the age-adjusted and sex-adjusted incidence rates for all ages became 32/ 100,000/year and 29/100,000/year, respectively. Of these, 40% (64) died by day 3 (day 0 defined as the day of hemorrhage), 43% (69) within 1 week, and 53% (84) within 1-6 months, respectively. When including the patients who may have died of SAH, the actual incidence rate of SAH is much higher than that which has been reported to date, and the actual mortality rate is still very high.

Study of Aneurysmal Subarachnoid Hemorrhage in Izumo City, Japan

Estimation of the actual incidence rate of subarachnoid hemorrhage and evaluation of the treatment require the inclusion of all patients in a defined geographic area. During 1987 through 1992 in Izumo City, Japan, we estimated the incidence rate of subarachnoid hemorrhage by including dead-on-arrival patients and by further adding the results obtained after reviewing all death certificates registered in this city in the corresponding period. In addition, we compared the management and surgical outcomes in hospitalized patients from 1987 through 1992 with outcomes from 1980 through 1986. During 1987 through 1992, we diagnosed 123 patients as having subarachnoid hemorrhage. The crude and the age- and sex-adjusted incidence rates using the 1990 population statistics for Japan were 25 (95% confidence interval, 21 to 30) per 100,000/y and 23 (95% confidence interval, 19 to 28) per 100,000/y for all ages, respectively; these occurrences are the highest among those reported to date. Of these patients, 8% died before receiving medical attention, 27% in the first week, and 39% at 1 month. The survival curve for 2 years improved significantly from 1980-1986 to 1987-1992 in patients with admission grades 4 and 5 (P = .035) and in operated patients with preoperative grades 1 through 3 (P = .036). However, there was little improvement in the overall management results (P = .168), possibly because patients with high risk and/or old age were admitted and/or diagnosed more often in the latter period. The incidence rate of subarachnoid hemorrhage is much higher than that reported so far in the literature, and despite improvement of management and surgical therapy, the actual case-fatality rate is still high, mainly because of the high mortality rate directly associated with the primary bleeding.

Has there been a decline in subarachnoid hemorrhage mortality?

We studied subarachnoid hemorrhage in the population of Rochester, Minnesota, for the 40-year period from 1945 through 1984. The average annual incidence rate of subarachnoid hemorrhage in Rochester has remained constant at approximately 11 per 100,000 population. Age-specific incidence rates increased with age. However, the average annual mortality rate for subarachnoid hemorrhage in Rochester has shown a decreasing trend, from 6.8 per 100,000 population in 1955-1964 to 4.3 in 1975-1984. It is likely that this is due to a decrease in case-fatality rates from 57% in 1945-1974 to 42% in 1975-1984 (p = 0.10). This decreasing trend was also evident in annual mortality rates from subarachnoid hemorrhage for US white men and women. The reason for the improved case-fatality rate is unclear, but it may be related to changes in management. The interval from onset of subarachnoid hemorrhage to surgery decreased from a median of 12 days in 1975-1979 to 2 days in 1980-1984, and of those who survived to receive medical attention, more patients received some form of medical treatment in 1980-1984. Whether either or both of these changes have led to the decrease in the case-fatality rate is uncertain.