Charles J. Moomaw

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.

Genetic and Environmental Risk Factors for Intracerebral Hemorrhage Preliminary Results of a Population-Based Study

Background and Purpose— Intracerebral hemorrhage (ICH) has a 30-day mortality rate of 40% to 50% and lacks a proven treatment. We report a preplanned, midpoint analysis of the first population-based, case-control study that examines both genetic and environmental risk factors of ICH. Methods— We prospectively identified cases of hemorrhagic stroke at all 16 hospitals in the Greater Cincinnati/Northern Kentucky region. All cases underwent medical record and neuroimaging review. Cases enrolled in the direct interview and genetic sampling arm of the study were matched to population-based control subjects by age, race, and sex. Multivariable logistic regression was performed to identify significant independent risk factors. Results— We enrolled 188 cases of ICH (67 lobar, 121 nonlobar) and 366 control subjects in the direct interview arm of the study. Significant independent risk factors for lobar ICH included the presence of an apolipoprotein E2 or E4 allele, frequent alcohol use, prior stroke, and first-degree relative with ICH. Significant independent risk factors for nonlobar ICH were hypertension, prior stroke, and first-degree relative with ICH. An increasing level of education was associated with a decreased risk of nonlobar ICH. The attributable risk of apolipoprotein E2 or E4 for lobar ICH was 29%, and the attributable risk of hypertension for nonlobar ICH was 54%. Conclusions— There is significant epidemiological evidence that the pathophysiology of ICH varies by location. We estimate that a third of all cases of lobar ICH are attributable to possession of an apolipoprotein E4 or E2 allele and that half of all cases of nonlobar ICH are attributable to hypertension.

Age at stroke: Temporal trends in stroke incidence in a large, biracial population

Objectives: We describe temporal trends in stroke incidence stratified by age from our population-based stroke epidemiology study. We hypothesized that stroke incidence in younger adults (age 20–54) increased over time, most notably between 1999 and 2005. Methods: The Greater Cincinnati/Northern Kentucky region includes an estimated population of 1.3 million. Strokes were ascertained in the population between July 1, 1993, and June 30, 1994, and in calendar years 1999 and 2005. Age-, race-, and gender-specific incidence rates with 95 confidence intervals were calculated assuming a Poisson distribution. We tested for differences in age trends over time using a mixed-model approach, with appropriate link functions. Results: The mean age at stroke significantly decreased from 71.2 years in 1993/1994 to 69.2 years in 2005 (p < 0.0001). The proportion of all strokes under age 55 increased from 12.9% in 1993/1994 to 18.6% in 2005. Regression modeling showed a significant change over time (p = 0.002), characterized as a shift to younger strokes in 2005 compared with earlier study periods. Stroke incidence rates in those 20–54 years of age were significantly increased in both black and white patients in 2005 compared to earlier periods. Conclusions: We found trends toward increasing stroke incidence at younger ages. This is of great public health significance because strokes in younger patients carry the potential for greater lifetime burden of disability and because some potential contributors identified for this trend are modifiable.

Eligibility for Recombinant Tissue Plasminogen Activator in Acute Ischemic Stroke: A Population-Based Study

Background and Purpose— Acute ischemic stroke patients are infrequently treated with recombinant tissue plasminogen activator (rtPA). We present unique population-based data regarding the eligibility of ischemic stroke patients for rtPA treatment. Methods— All ischemic strokes presenting to an emergency department (ED) within a biracial population of 1.3 million were identified. The patient was considered eligible for rtPA on the basis of exclusion criteria from the National Institute of Neurological Disorders and Stroke rtPA trial. Results— Of 2308 ischemic strokes, 1849 presented to an ED. Only 22% of all ischemic strokes in the population arrived in the ED in <3 hours from symptom onset; of these, 209 (51%) were ineligible for rtPA on the basis of mild stroke severity, medical and surgical history, or blood tests. Conclusions— In our population in 1993 to 1994, 8% of all ischemic stroke patients presented to an ED within 3 hours and met other eligibility criteria for rtPA. Even if time were not an exclusion for rtPA, only 29% of all ischemic strokes in our population would have otherwise been eligible for rtPA.

Subarachnoid Hemorrhage A Preventable Disease With a Heritable Component

Background and Purpose— Subarachnoid hemorrhage (SAH) caused by ruptured intracranial aneurysm affects approximately 16 000 Americans annually, and almost 40% of affected patients die within 30 days despite the best current therapy. Prevention of SAH is therefore of paramount importance. We present a preliminary analysis of risk factors for SAH from our population-based, case-control study. Methods— Cases were prospectively collected and matched 2:1 by age, race, and gender to controls using random digit dialing. Personal risk factor history, family history, neuroimaging data, and genetic samples were obtained. Univariate and bivariate analyses were performed and population-attributable risks estimated. Multivariable analysis was performed using conditional logistic regression. Results— Between June 1997 and February 2000, 107 cases and 197 controls were enrolled. In bivariate analyses, a large proportion of population-attributable risk for SAH could be explained by modifiable risk factors: smoking, hypertension, and heavy alcohol use. In multivariable analysis, current cigarette smoking, history of hypertension, frequent alcohol use, lower body mass index, and a family history of a relative with SAH or intracranial aneurysm were found to be significant, independent risk factors for SAH. Conclusion— Our data confirm previous reports that SAH clusters within some families independent of environmental risk factors, suggesting that SAH has a significant genetic component. Yet, even among families at increased risk of SAH, smoking cessation, treatment of hypertension, and reduced alcohol intake may substantially decrease SAH risk. The independent associations with heavy alcohol use and low body mass index with SAH may be confounded by smoking and require further study.

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.

Stroke Incidence is Decreasing in Whites, but Not in Blacks: A Population-Based Estimate of Temporal Trends in Stroke Incidence from the Greater Cincinnati/Northern Kentucky Stroke Study

Background and Purpose— Although other studies (in largely white populations) have found that stroke incidence declined during the 1990s, we previously reported that stroke incidence in our population (18% of which was black) did not change during that decade and that incidence rates in blacks were significantly higher than in whites. We sought to update temporal trends in stroke incidence by adding new data obtained from our large, biracial population in 2005. The objective of this study was to examine temporal trends in stroke incidence and case-fatality within a large biracial population over time by comparing stroke incidence rates from 1993 to 1994, 1999, and 2005. Methods— Within the Greater Cincinnati/Northern Kentucky population of 1.3 million, all strokes among area residents were ascertained at all local hospitals during July 1993 to June 19/94 and calendar years 1999 and 2005. A sampling scheme was used to ascertain cases in the out-of-hospital setting. Only first-ever strokes were included in this analysis. Race-specific incidence rates, standardized to the 2000 US Census population, and case-fatality rates were calculated. Results— The number of physician-confirmed first-ever strokes in patients ≥20 years of age was 1942 in 1993 to 1994, 2041 in 1999, and 1921 in 2005. In all study periods, blacks had higher stroke incidence than whites, and case-fatality rates were similar between races. In contrast to previous study periods, we found a significant decrease in overall stroke incidence in 2005. When stratified by race and stroke subtype, this change was driven by a decrease in ischemic stroke incidence among whites, whereas ischemic stroke incidence in blacks was unchanged. Hemorrhagic stroke incidence was unchanged in both races. Conclusions— For the first time, we report a significant decrease in stroke incidence within our population, which is consistent with other reports in the literature. This decrease was found only among whites, which suggests a worsening of the racial disparity in stroke incidence.

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.