Incidence Of Subarachnoid Hemorrhage Research Articles

Incidence and Risks of Subarachnoid Hemorrhage in China

To determine incidence and risks of subarachnoid hemorrhage in China. A prospective, population-based, 1:2 matched case-control study in Baotou, Inner Mongolia (≈2 million population) in 2009-2011. Multiple variable models used to determine relative risk and population-attributable risks for exposures. For a total of 226 patients (mean age, 59 years; 65% women; 434 controls), crude annual incidence (per 100 000) of subarachnoid hemorrhage was 6.2 (95% confidence intervals, 5.4-7.0); 4.3 (3.3-5.2) for men and 8.2 (6.9-9.6) for women. Compared with nonsmokers, adjusted relative risk of subarachnoid hemorrhage in current smokers was 2.31 (95% confidence interval, 1.31-4.09) but was 4.00 (1.62-9.89) in women. Population-attributable risk for smoking, hypertension, and low income were 18%, 36% and 59%, respectively. The incidence of subarachnoid hemorrhage in China is slightly lower than in Western countries and is related to smoking, hypertension, and poor socioeconomic status.

Every Peddler Praises His Own Needle: Have Clinical Rules in the Diagnosis of Subarachnoid Hemorrhage Supplanted Lumbar Punctures Yet?

1The authors state, “Research conducted among ED [emergency department] patients with possible acute coronary syndrome suggests that patients often have much higher risk thresholds for themselves than do the treating physicians.”1 AAssuming both patients and physicians are making rational decisions, list some reasons why they may have different risk thresholds. Do you think that emergency physicians have higher or lower risk thresholds than other physicians (eg, internists, pediatricians, neurosurgeons)? Why might this be so? Should our health care system try to align patient and physician acceptable risk thresholds? If so, how might this be achieved?BAssume 1) the 97% sensitivity reported for the Mark et al decision rule is externally validated and 2) the incidence of subarachnoid hemorrhage in patients presenting to the ED with acute headache is 2% and an emergency physician treats 3,500 patients per year. On average, how many years would an emergency physician have to apply this clinical rule to miss 1 subarachnoid hemorrhage? Do these sound like reasonable numbers to you? Why or why not?CNoncontrast computed tomography (CT) of the brain and lumbar punctures have associated complications. Summarize the reported frequency of complications associated with CT and lumbar puncture. Using the same data listed in question 1B, calculate how often these complications might occur. Does it matter that lumbar puncture–associated complications typically occur acutely, whereas noncontrast CT radiation exposure is associated with late-occurring morbidity and mortality? How might patient age factor into the likelihood of complications associated with CT and lumbar puncture?DIf this clinical rule were widely adopted, in 5 years would you expect that more or fewer patients would be investigated for subarachnoid hemorrhage (the use of similar decision aids in pulmonary embolism may serve as a useful example)?2The authors performed a matched control study. AUnder what circumstances are case-control studies ideal? Consider the time course of exposure and disease, the nature of the exposure and outcomes, and the frequency of the disease.BDiscuss the importance of matching in case-control studies. Why does one match? What should one match on? What should one not match on?CWhy did the authors choose 3 controls for each case? Why not 1? Why not 6?DWhat are the biases of case-control studies in general? In this study specifically?3The authors state, “Approximately 80% of subarachnoid hemorrhage cases are due to ruptured cerebral aneurysms.”1 AWhat are other common causes of nontraumatic subarachnoid hemorrhage?BIn general terms, describe the sensitivity of a noncontrast head CT in detecting these other causes. When choosing a screening test, is it preferable to be highly sensitive or highly specific? What test characteristic (ie, sensitivity, specificity) is desired for a confirmatory study?CAfter a patient complaint about a post–lumbar puncture headache, a hospital administrator proposes that the ED replace lumbar puncture with CT angiography when attempting to exclude subarachnoid hemorrhage in patients with a negative initial head CT result. What do you think about this, assuming the combination of CT and CT angiography is 99% sensitive for diagnosing a subarachnoid hemorrhage, as recently reported?24The authors performed a sensitivity analysis to assess the rule's stability, using a 1,000-iteration bootstrap analysis. AWhat is a sensitivity analysis? Why are sensitivity analyses often performed in observational studies?BWhat is a bootstrap analysis? Why are bootstrap analyses especially important when evaluating clinical decision rule performance? What assumptions are invoked by bootstrap analyses?

Impact of the moon on cerebral aneurysm rupture

Several external and internal risk factors for cerebral aneurysm rupture have been identified to date. Recently, it has been reported that moon phases correlate with the incidence of aneurysmal subarachnoid hemorrhage (SAH), however, another author found no such association. Therefore, the present study investigates the influence of the lunar cycle on the incidence of aneurysmal rupture, the initial clinical presentation, and the amount of subarachnoid blood. Lunar phase and the particular day of the lunar cycle were correlated to the date of aneurysm rupture, aneurysm location, initial clinical presentation, and amount of subarachnoid blood assessed from CT scans of all patients treated for basal SAH in our department from 2003 to 2010. We found no correlation between incidence of aneurysmal SAH, location of the aneurysm, initial clinical presentation, or amount of subarachnoid blood and the lunar cycle. The moon influences neither the incidence of aneurysmal SAH nor the grade of initial neurological deterioration or amount of subarachnoid blood.

Abstract P215: Trends in Hemorrhagic Stroke in Japan, from 1986 to 2010: Circulatory Risk in Communities Study (CIRCS).

Background: The incidence of hemorrhagic stroke has substantially decreased nearly to a quarter over years from 1960s to 1980s in Japan. However, there is little evidence on the trends after 1980, or whether subtypes of hemorrhagic stroke have decreased. We examined trends in the incidence of hemorrhagic stroke and its subtypes. Hypothesis: Hemorrhagic stroke have decreased after 1980s. For intraparenchymal hemorrhage (IPH), lobar and cerebellar intraparenchymal hemorrhage has not decreased. Methods: All residents aged 30 to 84 years in two communities (Akita and Osaka, census population: 18,998 in 2000) in Japan was surveyed. The incidence of IPH and subarachnoid hemorrhage (SAH) from 1986 to 2010 was ascertained by systematic surveillance of hospital records and confirmed by physicians with CT or MRI images. The implementation rate of CT or MRI has not changed materially over years (78.9~97.4%). IPH was further categorized to lobar and cerebellar IPH, and deep IPH (thalamus, basal ganglia or brainstem). The respective age-adjusted incidence rates per 100,000 person-years were calculated by each 5 years of time periods: 1986-1990, 1991-1995, 1996-2000, 2001-2005, and 2006-2010. Results: Age-adjusted incidence of SAH has decreased in 1996-2000 but increased after 2000. Respective age-adjusted incidence rates (per 100,000 person-years) of SAH for 5 time periods were 46.2, 46.5, 14.5, 23.0, and 23.7 (p for trend=0.23). Age-adjusted incidence of all IPH has decreased from 1986-1990 to 2006-2010. Respective incidence rates of IPH were 56.8, 53.7, 48.7, 29.0, and 26.5 (p for trend=0.01). For the subtypes of IPH, incidence of lobar and cerebellar IPH has not decreased from 1986-1990 to 2006-2010, while it have decreased for deep IPH. Respective incidence rates for lobar and cerebellar IPH were 13.1, 7.6, 16.6, 10.9, and 10.3 (p for trend=0.85) and those of deep IPH were 52.0, 53.1, 49.8, 40.8, and 29.5 (p for trend=0.03). Conclusion: The age-adjusted incidence of IPH after 1980s has decreased over years, although such trend was not clear for SAH. Among IPH, the incidence of lobar and cerebellar IPH has not decreased, while the incidence of deep IPH has decreased.

Hemorragia subaracnoidea y embarazo

The incidence of subarachnoid hemorrhage increases during pregnancy and involves a wide range of activities and issues such as the performance of imaging tests with radiological protection, assessment of fetal viability, termination of pregnancy, the patient's anesthetic management, the drugs to be used, and neurosurgical intervention.Early diagnosis and treatment of this event are essential to obtain favorable outcomes for the mother and fetus and to avoid complications.We describe three cases of intracranial hemorrhage with spontaneous onset during pregnancy registered at the Virgen de las Nieves’ Hospital between 2008 and 2010 and provide a review of the topic.

Dietary intake of saturated fatty acids and incident stroke and coronary heart disease in Japanese communities: the JPHC Study

Aims Although dietary saturated fatty acids (SFA) are considered atherogenic, associations between SFAs intake and stroke and coronary heart disease are still debated. We sought to test the hypothesis that SFA intake is associated inversely with risk of stroke and its subtypes and positively with coronary heart disease among Japanese, whose average SFA intake is lower than that of Westerners. Methods and results The Japan Public Health Center-based prospective Study involves two subcohorts: Cohort I, aged 45-64 in 1995 and followed-up through 2009, and Cohort II, aged 45-74 in 1998 and followed-up through 2007. A total of 38 084 men and 43 847 women were included in this report. Hazards ratios for incident total stroke, ischaemic stroke, intraparhenchymal haemorrhage, subarachnoid haemorrhage, myocardial infarction, and sudden cardiac death across quintiles of dietary SFAs were examined. We found inverse associations between SFA intake and total stroke [multivariable hazard ratio (95% confidence interval) for the highest vs. lowest quintiles = 0.77 (0.65-0.93), trend P = 0.002], intraparenchymal haemorrhage [0.61 (0.43-0.86), P for trend = 0.005], and ischaemic stroke [0.84 (0.67-1.06), trend P = 0.08], primarily for deep intraparenchymal haemorrhage [0.67 (0.45-0.99), P for trend = 0.04] and lacunar infarction [0.75 (0.53, 1.07), trend P = 0.02]. We also observed a positive association between SFAs intake and myocardial infarction [1.39 (0.93-2.08), trend P = 0.046] primarily among men. No associations were observed between SFAs intake and incidence of subarachnoid haemorrhage or sudden cardiac death. Conclusions In this Japanese population, SFAs intake was inversely associated with deep intraparenchymal haemorrhage and lacunar infarction and positively associated with myocardial infarction.

Epidemiology and genetics of intracranial aneurysms

Intracranial aneurysms are acquired lesions (5–10% of the population), a fraction of which rupture leading to subarachnoid hemorrhage with devastating consequences.Until now, the exact etiology of intracranial aneurysms formation remains unclear.The low incidence of subarachnoid hemorrhage in comparison with the prevalence of unruptured IAs suggests that the vast majority of intracranial aneurysms do not rupture and that identifying those at highest risk is important in defining the optimal management. The most important factors predicting rupture are aneurysm size and site.In addition to ambiental factors (smoking, excessive alcohol consumption and hypertension), epidemiological studies have demonstrated a familiar influence contributing to the pathogenesis of intracranial aneurysms, with increased frequency in first- and second-degree relatives of people with subarachnoid hemorrhage. In comparison to sporadic aneurysms, familial aneurysms tend to be larger, more often located at the middle cerebral artery, and more likely to be multiple.Other than familiar occurrence, there are several heritable conditions associated with intracranial aneurysm formation, including autosomal dominant polycystic kidney disease, neurofibromatosis type I, Marfan syndrome, multiple endocrine neoplasia type I, pseudoxanthoma elasticum, hereditary hemorrhagic telangiectasia, and Ehlers-Danlos syndrome type II and IV.The familial occurrence and the association with heritable conditions indicate that genetic factors may play a role in the development of intracranial aneurysms.Genome-wide linkage studies in families and sib pairs with intracranial aneurysms have identified several loci on chromosomes showing suggestive evidence of linkage, particularly on chromosomes 1p34.3–p36.13, 7q11, 19q13.3, and Xp22.For the loci on 1p34.3–p36.13 and 7q11, a moderate positive association with positional candidate genes has been demonstrated (perlecan gene, elastin gene, collagen type 1 A2 gene).Moreover, 3 of the polymorphisms analyzed in 2 genes (endothelial nitric oxide synthase T786C, interleukin-6 G572C, and interleukin-6 G174C) were found to be significantly associated with ruptured/unruptured aneurysms: the endothelial nitric oxide synthase gene single-nucleotide polymorphisms increased the risk, while IL-6 G174C seemed protective.More recently, two genomic loci (endothelin receptor A and cyclin-dependent kinase inhibitor 2BAS) have been found to be significantly associated with intracranial aneurysms in the Japanese population; endothelin-1 is a potent vasoconstrictor produced by the endothelial cells.Until now, there are no diagnostic tests for specific genetic risk factors to identify patients who are at a high risk of developing intracranial aneurysms.Knowledge of the genetic determinants may be useful in order to allow clues on stopping aneurysm formation and obtain diagnostic tools for identifying individuals at increased risk. Further multicenter studies have to be carried out.

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.

Outcome of Aneurysmal Subarachnoid Haemorrhage in the Elderly: Retrospective Study of a Contemporary Cohort Treated in a Regional Neuroscience Centre

Outcome of Aneurysmal Subarachnoid Haemorrhage in the Elderly: Retrospective Study of a Contemporary Cohort Treated in a Regional Neuroscience Centre The incidence of subarachnoid haemorrhage (SAH) increases with age, and together with the elderly constituting a significant and growing proportion of the population in developed countries, this poses unique challenges to the healthcare system. Treatment of SAH in the elderly is traditionally underrepresented due to pessimism toward its outcome. With recent advances in management techniques, it has been suggested that elderly patients with SAH may benefit from treatment.

Incidence of hemorrhagic stroke in the general population: validation of data from The Health Improvement Network

The Health Improvement Network (THIN) is a UK healthcare database composed of computerized information from primary care physicians (PCPs). We analyzed the validity of our method for identifying cases of intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) within THIN and assessed the incidence of these events. Patients aged 20-89 years were identified and followed until (i) ICH or SAH was detected, (ii) the patient reached 90 years old (iii) death, or (iv) the end of the study. Computerized patient profiles were reviewed manually; those not discarded became potential cases. A validation study was undertaken in 400 computer-detected cases (333 confirmed as potential cases; 67 discarded). PCPs completed a questionnaire to determine the actual incidence of ICH and SAH among these cases. We also assessed the incidence of ICH and SAH in the total cohort. A total of 4330 patients with a READ code suggesting hemorrhagic stroke were identified. Computerized profiles with free-text comments were reviewed manually to identify 3633 potential cases. Responses to the PCP questionnaire were received for 306 potential cases and 63 discarded cases (92% response rate); 82% of potential cases were confirmed. Finally, we identified 3137 cases of hemorrhagic stroke. Crude incidence was 15 per 100,000 person-years for ICH and 11 per 100,000 person-years for SAH; the overall incidence increased sharply with age. Computer detection of cases of hemorrhagic stroke in THIN followed by manual review of clinical profiles is a valid method. The incidence of hemorrhagic stroke increases sharply with age.

The Natural Course of Unruptured Cerebral Aneurysms

The Natural Course of Unruptured Cerebral Aneurysms

Female risk factors for subarachnoid hemorrhage

To systematically review the literature on female risk factors and risk of SAH. We searched Medline and EMBASE for articles published between January 1985 and July 2011. For all studies fulfilling the predefined criteria, we obtained risk ratios (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) for female risk factors. We pooled crude and adjusted ORs (aORs) with a general variance-based random-effects method. We evaluated methodologic quality with the Newcastle-Ottawa Scale. We included 16 studies; 8 had good quality. Twelve studies had a case-control design, 3 studies had a longitudinal design, and 1 study had a case-crossover design. Overall aORs were 1.31 (95% CI 1.05-1.64; 5 studies, 2 with good quality [GQ]) for current use of combined oral contraceptives (COC), 0.90 (95% CI 0.74-1.09; 7 studies, 4 GQ) for ever COC use, 0.86 (95% CI 0.69-1.08; 6 studies, 3 GQ) for current use of hormone replacement therapy (HRT), 0.74 (95% CI 0.54-1.00; 3 studies, 1 GQ) for ever use of HRT, and 1.29 (95% CI 1.03-1.61; 5 studies, 2 GQ) for postmenopausal women. Data on parity and age at menarche were heterogeneous. Risk of subarachnoid hemorrhage (SAH) was not increased during pregnancy, labor, or puerperium (RR 0.40, 95% CI 0.20-0.90; 1 GQ study). Female hormone levels might influence risk of SAH, but the pathophysiology of this effect and its influence on the difference in incidence of SAH between the sexes remains unclear. Further studies are needed to identify modifiable risk factors of SAH in women older than age 50.

Lung Function as a Risk Factor for Subarachnoid Hemorrhage

The etiology of subarachnoid hemorrhage (SAH) is poorly understood. Reduced lung function, expressed as low forced expiratory volume in 1 second (FEV(1)) and low forced vital capacity (FVC), is a predictor of cardiovascular disease, but whether reduced lung function is a risk factor for SAH is not known. The association between lung function and incidence of SAH was investigated in a prospective cohort study. Between 1974 and 1992, 20 534 men and 7237 women (mean age, 44 years) were examined in a health screening program including spirometry. The incidence of SAH was studied during a mean follow-up of 26 years in relation to age- and height-standardized FEV(1), FVC, and FEV(1)/FVC. One hundred forty-five subjects had a SAH (18.3 per 100 000 person-years in men and 26.5 per 100 000 person-years in women). The hazard ratio for SAH in the lowest compared to the highest quartile of FEV(1) and FEV(1)/FVC was 2.24 (95% CI, 1.32-3.81; P for trend=0.014) and 1.92 (95% CI, 1.14-3.23; P for trend=0.003), respectively, after adjustment for several confounding factors including smoking and hypertension. The results persisted when analysis was restricted to nonsmokers. FVC showed no significant association with incidence of SAH. Baseline lung function, expressed as low FEV(1) or FEV(1)/FVC, is a risk factor for SAH, independently of smoking.

O-009 Younger age of menopause in women with cerebral aneurysms

BackgroundThe incidence of subarachnoid hemorrhage in women surges following menopause. Estrogen fluctuations have been implicated in cerebral aneurysm formation, growth and rupture and is thought to explain the well known...

Younger age of menopause in women with cerebral aneurysms

BackgroundThe incidence of subarachnoid hemorrhage in women surges following menopause. Estrogen fluctuations have been implicated in cerebral aneurysm formation, growth and rupture and are thought to explain the well-known gender...

Subarachnoid Hemorrhage Incidence in the United States Does Not Vary with Season or Temperature

Previous studies have suggested seasonal variations in rates of spontaneous rupture of intracranial aneurysms, leading to potentially devastating SAH. In an effort to identify a seasonal effect, variation in SAH incidence and in-hospital mortality rates were examined as they relate to admission month, temperature, and climate using HCUP's Nationwide Inpatient Sample. Cases of nontraumatic SAH and subsequent in-hospital mortality were extracted from the 2001-2008 NIS and associated with month of occurrence, local average monthly temperatures, and USDA climate zone. Multivariate regression analysis was used to study how admission month, temperature, and climate affected SAH admission and mortality rates. Among 57,663,486 hospital admissions from the 2001-2008 NIS, 52,379 cases of spontaneous SAH (ICD-9-CM 430) and 13,272 cases of subsequent in-hospital mortality were identified. SAH incidence and in-hospital mortality rates were not significantly correlated with a monthly/seasonal effect (incidence, χ(2) = 2.94, P = .99; mortality, χ(2) = 6.91, P = .81). However, SAH incidence significantly varied with climate (P < .0001, zones 11 and 7) but not with temperature (P = .1453), whereas average monthly temperature and climate had no significant correlation with in-hospital mortality (temperature, P = .3005; climate, P = .0863). We identified no significant monthly or temperature-related effect in the incidence of SAH. Our data suggest that certain climate zones within the United States may be associated with significantly different SAH incidence, but the origins of these differences remain unclear and are probably unrelated to meteorologic variables.

Epidemiology of subarachnoid hemorrhage in the Yaeyama Islands, an isolated subtropical region of Japan most frequently affected by typhoons: A population-based study

ObjectiveThe present study analyzed epidemiological data for patients with subarachnoid hemorrhage (SAH) in a subtropical region of Japan that is the most frequently affected by typhoons. Patients and methodsThe medical records of hospitalized patients who had been diagnosed as having SAH at Okinawa Prefectural Yaeyama Hospital during a 13-year period were reviewed. Demographic and epidemiological data including date and time of onset and activity at onset and clinical data were collected. Meteorological data for typhoon's approaches to the Yaeyama Islands were obtained from the web-site of the Japan Meteorological Agency. In addition, patients who had developed SAH during a period of 3days before and after the closest approach of a typhoon (CAT) were examined. ResultsA total of 94 patients were identified. A monthly peak in August, a weekly peak on Monday, and two daily peaks in the evening and morning were observed. The incidence of SAH during a period of 3days before and after the CAT was approximately twice as high as that on other days, and a statistically significant difference was found. ConclusionPeriodic patterns of SAH onset revealed unusual monthly and circaseptan variations and the usual circadian variation. SAH onset was associated with typhoon's approaches.

Forensic Evaluation of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) may occur with natural, accidental, homicidal, suicidal, and/or undetermined events. The forensic autopsy and death scene investigation are useful in reconstructing the mechanism of death, as well as the dynamics of the event. Therefore, an accurate forensic evaluation of SAH is crucial. The annual incidence of subarachnoid hemorrhage in the United States is estimated at 1 per 10,000 persons with a median age of 50 years, and a high mortality rate. SAH is the most common indicator of traumatic brain injury (TBI). The majority (80%) of nontraumatic SAH is due to a ruptured saccular aneurysm. Other causes of nontraumatic SAH include arteriovenous malformations, cavernous angiomas, mycotic aneurysms, neoplasms, blood dyscrasias, perimesencephalic hemorrhage and central venous thrombosis. Risk factors for nontraumatic SAH include cigarette smoking, hypertension, cocaine use, heavy alcohol use, and a first-degree relative with subarachnoid hemorrhage. The rate and amount of hemorrhage determine the morbidity and mortality of the lesion. Computed tomography (CT) is considered the study of choice for ante-mortem identification of SAH. In rare circumstances, however, a similar CT appearance may occur in the absence of blood in the subarachnoid space. Such “pseudo-subarachnoid hemorrhage” is confirmed when autopsy shows no subarachnoid hemorrhage in those carrying the premortem CT diagnosis. However, when true SAH is present, dating of the hemorrhage, by both gross and microscopic examination, may aid in the forensic evaluation.

Incidence of subarachnoid haemorrhage: An Australian national hospital morbidity database analysis

Incidences of subarachnoid haemorrhage (SAH) in Australia have been reported in regional studies with variable rates. We investigated the national SAH rate and evaluated the trend over the 10years from 1998 to 2008. The crude SAH incidence, not related to trauma or arteriovenous malformation, was estimated at 10.3 cases per 100,000 person-years (95% confidence interval [CI]: 10.2–10.4). Females have a higher incidence of SAH (12.5 cases per 100,000; 95% CI: 12.3–12.8) compared to males (8.0 cases per 100,000; 95% CI: 7.8–8.3), with age-adjusted incidence increases with increasing age for both sexes. Less than 10% of SAH occurred in the first three decades of life. The peak age group for patients to experience SAH was between 45years and 64years, accounting for almost 45% of the overall annual SAH admissions. Aneurysms located in the anterior circulation were a more common source of rupture compared to those located in the posterior circulation (rate ratio 3.9; 95% CI: 3.6–4.2). Contrary to contemporary observations in the literature, we did not observe a decline in the incidence of SAH during this specified study period.

Abstract 185: Declining Subarachnoid Hemorrhage Case-Fatality Rates in a Population

Introduction: In the last few decades there have been several medical advances in the care of patients with subarachnoid hemorrhage (SAH). But few population-based studies (and none in the United States) have examined outcomes in the same population over time. Methods: All SAHs among residents of the Greater Cincinnati/Northern Kentucky (GCNK) region at least 20 years of age were identified using ICD-9 codes 430-436 and verified via study physician review in four distinct study periods. An incidence rate for each time period was calculated. Baseline characteristics, including demographics, risk factors, and functional status, were ascertained, along with hospital discharge modified Rankin score and all-cause 30- and 90-day case-fatality. Results: We identified 78 SAHs among residents of the GCNK region in 1988, 85 from 7/1993 to 6/1994, 95 in 1999, and 91 in 2005. The incidence of SAH in the four study periods (age-, race-, and sex-adjusted to the 2000 US population) was 9.4, 9.3, 10.0, and 9.0 per 100,000, respectively. Of the 349 SAHs in the study periods, 326 were diagnosed in an ED or hospital setting, while 23 were diagnosed on autopsy alone. All-cause 30- and 90-day case-fatality rates declined significantly from 1988 to 2005 ( Table ), even when all autopsy-alone cases were excluded. Conclusions: While the incidence of SAH remained stable in this population-based region, the 30-day and 90-day case-fatality rates declined significantly. Advances in surgical and medical management, along with systems-based changes such as the emergence of neurocritical care units, have likely led to reduced case-fatality. Future studies should explore the impact of specific factors related to improved case-fatality rates.