Alexander Schneider

Incidence and Short-Term Prognosis of Transient Ischemic Attack in a Population-Based Study

Background and Purpose— Transient ischemic attacks (TIAs) have been shown to be a strong predictor of subsequent stroke and death. We present the incidence and short-term prognosis of TIA within a large population with a significant proportion of minorities with out-of-hospital TIA. Methods— TIA cases were identified between July 1, 1993 and June 30, 1994 from the Greater Cincinnati/Northern Kentucky population of 1.3 million inhabitants by previously published surveillance methods, including inpatient and out-of-hospital events. Incidence rates were adjusted to the 1990 population, and life-table analyses were used for prognosis. Results— The overall race, age, and gender-adjusted incidence rate for TIA within our population was 83 per 100 000, with age, race, and gender adjusted to the 1990 US population. Blacks and men had significantly higher rates of TIA than whites and women. Risk of stroke after TIA was 14.6% at 3 months, and risk of TIA/stroke/death was 25.2%. Age, race, and sex were not associated with recurrent TIA or subsequent stroke in our population, but age was associated with mortality. Conclusions— Using our incidence rates for TIA in blacks and whites, we conservatively estimate that ≈240 000 TIAs occurred in 2002 in the United States. Our incidence rate of TIA is slightly higher than previously reported, which may be related to the inclusion of blacks and out-of-hospital events. There are racial and gender-related differences in the incidence of TIA. We found a striking risk of adverse events after TIA; however, there were no racial or gender differences predicting these events. Further study is warranted in interventions to prevent these adverse events after TIA.

Stroke in a Biracial Population The Excess Burden of Stroke Among Blacks

Background and Purpose— Excess mortality resulting from stroke is an important reason why blacks have higher age-adjusted mortality rates than whites. This observation has 2 possible explanations: Strokes occur more commonly among blacks or blacks have higher mortality rates after stroke. Our population-based epidemiological study is set in the Greater Cincinnati/Northern Kentucky region of 1.31 million people, which is representative of the US white and black populations with regard to many demographic and socioeconomic characteristics. Methods— Hospitalized cases were ascertained by International Classification of Diseases (ninth revision) discharge codes, prospective screening of emergency department admission logs, and review of coroner’s cases. A sampling scheme was used to ascertain cases in the out-of-hospital setting. All potential cases underwent detailed chart abstraction by study nurses, followed by physician review. Race-specific incidence and case fatality rates were calculated. Results— We identified 3136 strokes during the study period (January 1, 1993, to June 30, 1994). Stroke incidence rates were higher for blacks at every age, with the greatest risk (2- to 5-fold) seen in young and middle-aged blacks (<65 years of age). Case fatality rates did not differ significantly in blacks compared with whites. Applying the resulting age- and race-specific rates to the US population in 2002, we estimate that 705 000 to 740 000 strokes have occurred in the United States, with a minimum of 616 000 cerebral infarctions, 67 000 intracerebral hemorrhages, and 22 000 subarachnoid hemorrhages. Conclusions— Excess stroke-related mortality in blacks is due to higher stroke incidence rates, particularly in the young and middle-aged. This excess burden of stroke incidence among blacks represents one of the most serious public health problems facing the United States.

Ischemic Stroke Subtypes. A Population-Based Study of Incidence Rates Among Blacks and Whites

Background and Purpose— Blacks have an excess burden of stroke compared with whites; however, data comparing ischemic stroke subtypes among the 2 groups are limited and typically involve relative frequencies. The objective of this study is to compare the incidence rates of ischemic stroke subtypes between blacks and whites within a large, representative, biracial population. Methods— The Greater Cincinnati/Northern Kentucky Stroke Study is designed to measure incidence rates and trends of all strokes within a well-defined, large, biracial population. Hospitalized cases were ascertained by International Classification of Disease (9th revision; ICD-9) discharge codes. Out-of-hospital events were ascertained by prospective screening of emergency department admission logs, review of coroners’ cases, and monitoring all public health and hospital-based primary care clinics. A sampling scheme was used to ascertain events from nursing homes and all other primary care physician offices. All potential cases underwent detailed chart abstraction and confirmed by physician review. Based on all available clinical, laboratory, and radiographic information, ischemic stroke cases were subtyped into the following categories: cardioembolic, large-vessel, small-vessel, other, and stroke of undetermined cause. Race-specific incidence rates were calculated and compared after adjusting for age and gender, and standardizing to the 1990 US population. Results— Between July 1, 1993, and June 30, 1994, 1956 first-ever ischemic strokes occurred among blacks and whites in the study population. Small-vessel strokes and strokes of undetermined cause were nearly twice as common among blacks. Large-vessel strokes were 40% more common among blacks than whites, and there was a trend toward cardioembolic strokes being more common among blacks. Conclusions— The excess burden of ischemic strokes among blacks compared with whites is not uniformly spread across the different subtypes. Large-vessel strokes are more common and cardioembolic stroke are as common among blacks, traditionally thought to be more common among whites.

The Unchanging Incidence and Case-Fatality of Stroke in the 1990s A Population-Based Study

Background and Purpose— Many advances were made in stroke prevention strategies during the 1990s, and yet temporal trends in stroke incidence and case-fatality have not been reported in the United States. Blacks have a 2-fold higher risk of stroke; however, there are no data over time showing if any progress has been made in reducing racial disparity in stroke incidence. The objective of this study was to examine temporal trends in stroke incidence and case-fatality within a large, biracial population during the 1990s. Methods— Within a biracial population of 1.3 million, all strokes were ascertained at all local hospitals using International Classification of Diseases, 9th Revision codes during July 1993 to June 1994 and again in 1999. A sampling scheme was used to ascertain cases in the out-of-hospital setting. Race-specific incidence and case-fatality rates were calculated and standardized to the 2000 US Census population. A population-based telephone survey regarding stroke risk factor prevalence and medication use was performed in 1995 and 2000. Results— There were 1954 first-ever strokes in 1993–1994 and 2063 first-ever strokes in 1999. The annual incidence of first-ever hospitalized stroke did not significantly change between study periods: 158 per 100 000 in both 1993–1994 and 1999 (P=0.97). Blacks continue to have higher stroke incidence than whites, especially in the young; however, case-fatality rates continue to be similar between races and are not changing over time. Medication use for treatment of stroke risk factors significantly increased in the general population between study periods. Conclusions— Despite advances in stroke prevention treatments during the 1990s, the incidence of hospitalized stroke did not decrease within our population. Case-fatality also did not change between study periods. Excess stroke mortality rates seen in blacks nationally are likely the result of excess stroke incidence and not case-fatality, and the racial disparity in stroke incidence did not change over time.

Racial Variations in Location and Risk of Intracerebral Hemorrhage

Background and Purpose— Risk factors for intracerebral hemorrhage (ICH) vary by location. Incidence rates of ICH are known to be higher in American blacks than whites, but how rates may differ by hemorrhage location is unknown. We sought to define incidence rates for different ICH locations in a biracial population. Methods— All hospitalized patients age ≥20 years with spontaneous ICH were identified in the Greater Cincinnati/Northern Kentucky metropolitan area from May 1998 to July 2001 and August 2002 to April 2003. Incidence rates per 100 000 persons were age, sex, and race adjusted as appropriate to the 2000 US population. Risk ratios (RRs) with 95% CIs were calculated from unadjusted incidence rates. Results— There were 1038 qualifying ICHs. Annual incidence rates per 100 000 persons ≥20 years of age were 48.9 for blacks and 26.6 for whites. Annual incidence rates per 100 000 blacks in lobar, deep cerebral, brain stem, and cerebellar locations were 15.2, 25.7, 5.1, and 2.9, respectively. Annual incidence rates per 100 000 whites in the same locations were 9.4, 13.0, 1.3, and 2.9. The greatest excess risk of ICH in blacks compared with whites was found among young to middle-aged (35 to 54 years) persons with brain stem (RR, 9.8; 95% CI, 4.2 to 23.0) and deep cerebral (RR, 4.5; 3.0 to 6.8) hemorrhage. Conclusions— The excess risk of ICH in American blacks is largely attributable to higher hemorrhage rates in young and middle-aged persons, particularly for deep cerebral and brain stem locations. Hypertension is the predominant risk factor for hemorrhages in these locations.

Effect of Untreated Hypertension on Hemorrhagic Stroke

Background and Purpose— Stroke is the third leading cause of death and the leading cause of disability in the United States. Intracerebral hemorrhage and subarachnoid hemorrhage represent ≈20% of all stroke cases and have a mortality rate of 40% to 50%. Hypertension is an important risk factor for these subtypes of stroke. We sought to determine whether untreated hypertension carries a different risk from treated hypertension for hemorrhagic stroke. Methods— Cases of hemorrhagic stroke in the greater Cincinnati region were identified by screening all area hospital emergency rooms, radiology reports, and International Classification of Diseases 9 codes. Medical records were reviewed for risk factors and medication use. Cases of hemorrhagic stroke were approached for enrollment into the genetic sampling and interview arm. If subjects agreed, the case was matched by age, race, and gender to population-based controls. Results— Between May 1997 and December 2002, we recruited 549 cases of hemorrhagic stroke, of which 322 were intracerebral hemorrhage and 227 were subarachnoid hemorrhage. Untreated hypertension was found to be a significant risk factor for hemorrhagic stroke (odds ratio [OR]= 3.5 [2.3 to 5.2]; P <0.0001) as was treated hypertension (OR = 1.4 [1.0 to 1.9]; P = 0.03). Insurance status of “self-pay” or Medicaid was a significant risk factor for untreated hypertension (OR = 2.7 [1.6 to 4.4]). We estimate that 17% to 28% of hemorrhagic strokes among hypertensive patients would have been prevented if they had been on hypertension treatment. Conclusion— Untreated hypertension is highly prevalent and an important risk factor for hemorrhagic stroke. We estimate that among hypertensive subjects, approximately one fourth of hemorrhagic strokes would be prevented if all hypertensive subjects received treatment.

Hypercholesterolemia, HMG-CoA Reductase Inhibitors, and Risk of Intracerebral Hemorrhage: A Case–Control Study

Background and Purpose— Several studies have demonstrated an association between hypocholesterolemia and intracerebral hemorrhage (ICH). We tested the hypothesis that hypercholesterolemia or use of HMG-CoA reductase inhibitors (statin) agents, or both, are associated with ICH. Methods— This study was part of the preplanned midway analysis of an ongoing, population-based, case-control study of the genetic and environmental risk factors of hemorrhagic stroke. Conditional stepwise logistic regression modeling was used to determine if self-reported hypercholesterolemia or statin use, or both, were independent risk factors for ICH. Results— Between December 1, 1997, and June 30, 2000, 188 cases of ICH and 366 age-, race-, and gender-matched controls were enrolled. Hypercholesterolemia and statin use were less common among cases than controls: 25% versus 38% (P=0.003) and 9% versus 17% (P=0.03), respectively. Hypercholesterolemia with statin use was associated with less risk of ICH (OR=0.30; P=0.0008) in multivariable analysis after controlling for alcohol use, hypertension, previous stroke, first-degree relative with ICH, education level, and apolipoprotein E alleles. Conclusion— Hypercholesterolemia was associated with a lower risk of ICH. We have not found an increased risk of ICH with the widespread use of statins in our population. Given the lack of cholesterol levels in the current study, further studies are needed to determine if lower cholesterol levels secondary to statin use bear the same risk as low cholesterol levels for ICH.

Association of Apolipoprotein E4 and Haplotypes of the Apolipoprotein E Gene With Lobar Intracerebral Hemorrhage

Background and Purpose— Conflicting reports in the literature exist with regard to the association of apolipoprotein E (apo E) alleles and lobar intracerebral hemorrhage (ICH). We genotyped 12 single-nucleotide polymorphisms in the 5′ upstream regulatory, exonic, and intronic regions of the apo E gene and performed genotype and haplotype association analyses. Methods— We prospectively enrolled subjects with hemorrhagic stroke and matched them with 2 controls based on age, race, and sex. Each case was reviewed by a physician to determine case status and location of the ICH. Multivariate logistic-regression modeling with backward elimination was used to determine significant risk factors for lobar ICH. Associations at the genotype and haplotype levels and linkage disequilibrium were conducted according to standard statistical methods. Results— Between May 1997 and December 2002, 315 cases of ICH were recruited, of whom 107 were lobar ICH cases matched to 205 controls. No association was found for apo E2, E3, or E4 with nonlobar ICH. Independent, significant risk factors for lobar ICH included apo E4, untreated hypertension, anticoagulant use, a first-degree relative with ICH, and ≤high school education (compared with >high school education). Treated hypercholesterolemia compared with “no history of hypercholesterolemia” was associated with a decreased risk of lobar ICH. Haplotype association analysis demonstrated a significant association of the apo E gene with lobar ICH among whites (P<0.0001) and blacks (P=0.0024). Conclusions— Apo E4 is independently associated with lobar ICH but not nonlobar ICH. Haplotypes of the apo E gene are associated with lobar ICH. Untreated hypertension is a risk factor for lobar ICH.

Community socioeconomic status and prehospital times in acute stroke and transient ischemic attack : Do poorer patients have longer delays from 911 call to the emergency department?

Background and Purpose— Timely access to medical treatment is critical for patients with acute stroke because acute therapies must be given very quickly after symptom onset. We examined the effect of socioeconomic status on prehospital delays in stroke and transient ischemic attack (TIA) patients within a large, biracial population. Methods— By screening all local hospital ICD-9 codes 430 to 436, all stroke and TIA patients were identified during the calendar year of 1999. Cases must have used emergency medical services (EMS), lived at home, had their stroke at home, and had documented times of the 911 call and arrival to the emergency department. Socioeconomic status was estimated using economic data regarding the geocoded home residence census tract. Results— Only 38% of stroke and TIA patients used EMS. There were 978 cases of stroke and TIA included in this analysis. The mean times were call to arrival on scene 6.5 minutes, on-scene time 14.1 minutes, and transport time 13.1 minutes. Lower community socioeconomic status was associated with all 3 EMS time intervals; however, all time differences were small: the largest difference was 5 minutes. Conclusions— Within our population, living in a poorer area does not appear to delay access to acute care for stroke in a clinically significant way. We did find small, statistically significant delays in prehospital times that were associated with poorer communities, black race, and increasing age. However, delays related to public recognition of stroke symptoms, and limited use of 911, are likely much more important than these small delays that occur with EMS systems.

Impact of socioeconomic status on stroke incidence: A population‐based study

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