Biomedical subjects

Melinda A Smith

Publications and source records attributed to Melinda A Smith.

14 recordsLinked to original sources

PubMed2006

Defining cause of death in stroke patients: The Brain Attack Surveillance in Corpus Christi Project.

Stroke mortality is an important national health statistic and represents a frequent endpoint for epidemiologic studies. Several methods have been used to determine cause of death after stroke, but their agreement and reliability are unknown. Two hundred consecutive deaths of transient ischemic attack or ischemic stroke patients were identified (January 2000-September 2001) from an ongoing population-based stroke surveillance study in Texas, The Brain Attack Surveillance in Corpus Christi Project. Two neurologists independently recorded the cause of death based on two methods: 1) determining the underlying cause of death as defined by the World Health Organization, and 2) determining whether the death was stroke related. Kappa statistics with 95% confidence intervals were calculated by comparing agreement between methods within reviewers and between reviewers within methods. Agreement between the two cause-of-death-determination methods for each neurologist was 0.41 (95% confidence interval (CI): 0.31, 0.51) and 0.47 (95% CI: 0.38, 0.58), respectively. Agreement between neurologists for the underlying-cause-of-death method was 0.46 (95% CI: 0.32, 0.60); for the stroke-related method, it was 0.63 (95% CI: 0.52, 0.75). Accurate, reliable determinations of cause of death after stroke/transient ischemic attack are not currently feasible. More research is needed to identify a reliable process for coding cause of death from stroke.

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PubMed2006

Stroke among patients with dizziness, vertigo, and imbalance in the emergency department: a population-based study.

BACKGROUND AND PURPOSE: Dizziness, vertigo, and imbalance are common presenting symptoms in the emergency department. Stroke is a leading concern even when these symptoms occur in isolation. The objective of the present study was to determine the "real-world" proportion of stroke among patients presenting to the emergency department with these dizziness symptoms (DS). METHODS: From a population-based study, patients >44 years of age presenting with DS to the emergency department, or directly admitted to the hospital, were identified. Demographics, the frequency of new cerebrovascular events, and the frequency of isolated DS (ie DS with no other stroke screening term or accompanying neurologic signs or symptoms) were assessed. Multivariable logistic regression was used to evaluate the association of age, gender, ethnicity, and isolated DS with stroke/transient ischemic attack (TIA). The association of the presenting symptoms with stroke/TIA was also assessed. RESULTS: Stroke/TIA was diagnosed in 3.2% (53 of 1666) of all patients with DS. Only 0.7% (9 of 1297) of those with isolated DS had a stroke/TIA. Patients with stroke/TIA were slightly older than those without stroke/TIA (69.3+/-11.7 vs 65.3+/-12.9, P=0.02). Male gender was associated with stroke/TIA, whereas isolated DS was negatively associated with stroke/TIA. Patients with imbalance (dizziness as referent) were more likely to have stroke/TIA. CONCLUSIONS: The proportion of cerebrovascular events in patients presenting with dizziness, vertigo, or imbalance is very low. Isolated dizziness, vertigo, or imbalance strongly predicts a noncerebrovascular cause. The symptom of imbalance is a predictor of stroke/TIA.

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PubMed2006

Ethnic differences in stroke recurrence.

OBJECTIVE: To determine whether stroke recurrence and the effect of recurrence on mortality differ by ethnicity. METHODS: Using methods from the Brain Attack Surveillance in Corpus Christi project, we prospectively identified first-ever ischemic strokes from emergency department logs and hospital admissions (January 2000 to December 2004). Recurrent strokes and deaths were identified for the same period. Cumulative probability of stroke recurrence was estimated. Cox proportional hazards models were used to examine ethnic differences in recurrence and to examine the relation among ethnicity, recurrence, and mortality. RESULTS: During the time interval, 1,345 first-ever ischemic strokes were validated. Median age of patients was 72 years; 53% were Mexican American (MA). There were 126 recurrent strokes. Cumulative risk for recurrence at 30 days and 1 year was 2.6 and 7.5%, respectively. MAs had higher risk for stroke recurrence (risk ratio, 1.57; 95% confidence interval, 1.05-2.34) compared with non-Hispanic white patients, adjusted for demographics, stroke risk factors, and stroke severity. Stroke recurrence was related to mortality to a similar extent across ethnic groups (non-Hispanic white patients: risk ratio, 3.32; 95% confidence interval, 2.07-5.32; MAs: risk ratio, 2.35; 95% confidence interval, 1.42-3.88). INTERPRETATION: MAs had higher stroke recurrence risk compared with non-Hispanic white patients. Stroke recurrence had an important impact on mortality. Efforts to reduce stroke recurrence in MAs are needed.

Age Factors↗

PubMed2005

Family history and stroke outcome in a bi-ethnic, population-based stroke surveillance study.

BACKGROUND: The genetic epidemiology of ischemic stroke remains relatively unstudied, and information about the genetic epidemiology of ischemic stroke in populations with significant minority representation is currently unavailable. METHODS: The Brain Attack Surveillance in Corpus Christi project (BASIC) is a population-based stroke surveillance study conducted in the bi-ethnic community of Nueces County, Texas, USA. Completed ischemic strokes were identified among patients 45 years or older seen at hospitals in the county between January 1, 2000-December 31, 2002. A random sample of ischemic stroke patients underwent an in-person interview and detailed medical record abstraction (n = 400). Outcomes, including initial stroke severity (NIH stroke scale), age at stroke onset, 90-day mortality and functional outcome (modified Rankin scale > or = 2), were studied for their association with family history of stroke among a first degree relative using multivariable logistic and linear regression. A chi-square test was used to test the association between family history of stroke and ischemic stroke subtype. RESULTS: The study population was 53.0% Mexican American and 58.4% female. Median age was 73.2 years. Forty percent reported a family history of stroke among a first degree relative. Family history of stroke was borderline significantly associated with stroke subtype (p = 0.0563). Family history was associated with poor functional outcome in the multivariable model (OR = 1.87; 95% CI: 1.14-3.09). Family history was not significantly related to initial stroke severity, age at stroke onset, or 90-day mortality. CONCLUSION: Family history of stroke was related to ischemic stroke subtype and to functional status at discharge. More research is needed to understand whether stroke subtype would be a useful selection criterion for genetic association studies and to hypothesize about a possible genetic link to recovery following ischemic stroke.

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PubMed2005

Gender comparisons of diagnostic evaluation for ischemic stroke patients.

BACKGROUND: Sixty-two percent of all stroke deaths in the United States occur in women. We compared diagnostic evaluations by gender in ischemic stroke patients in a biethnic, population-based study. METHODS: A random sample of patients with ischemic stroke identified between 2000 and 2002 by BASIC (Brain Attack Surveillance in Corpus Christi Project) were selected for this study (n = 381). Gender differences in the use of stroke diagnostic tests were assessed. Separate multivariable logistic regression models predicting diagnostic test use were constructed, adjusted for age, ethnicity, hypertension, atrial fibrillation, diabetes, history of stroke, coronary artery disease, having a primary care provider, discharge disposition, modified Rankin Scale score at discharge, and insurance status. RESULTS: The study population consisted of 161 men and 220 women. Median age was 74.3 years. The respective proportions of males and females receiving any carotid artery evaluation were 71% and 62%; brain MRI, 43% and 41%; echocardiography, 57% and 48%; and EKG, 90% and 86%. Multivariable logistic models found that women were less likely to undergo echocardiography (odds ratio [OR] 0.64, CI: 0.42 to 0.98) and carotid evaluation (OR 0.57, CI: 0.36 to 0.91). There was no association of ischemic stroke subtype and gender to explain these results (p = 0.76). CONCLUSIONS: Despite controlling for explanatory variables, women with stroke were less likely to receive standard diagnostic tests vs men. Intervention is needed to increase access to quality stroke care for women.

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PubMed2005

Stroke burden in Mexican Americans: the impact of mortality following stroke.

PURPOSE: To estimate ethnic-specific all-cause mortality risk following ischemic stroke and to compare mortality risk by ethnicity. METHODS: DATA from the Brain Attack Surveillance in Corpus Christi Project, a population-based stroke surveillance study, were used. Stroke cases between January 1, 2000 and December 31, 2002 were identified from emergency department (ED) and hospital sources (n = 1,234). Deaths for the same period were identified from the surveillance of stroke cases, the Texas Department of Health, the coroner, and the Social Security Death Index. Ethnic-specific all-cause cumulative mortality risk was estimated at 28 days and 36 months using Kaplan Meier analysis. Cox proportional hazards regression was used to compare mortality risk by ethnicity. RESULTS: Cumulative 28-day all-cause mortality risk for Mexican Americans (MAs) was 7.8% and for non-Hispanic whites (NHWs) was 13.5%. Cumulative 36-month all-cause mortality risk was 31.3% in MAs and 47.2% in NHWs. MAs had lower 28-day (RR = 0.58; 95% CI: 0.41, 0.84) and 36-month all-cause mortality risk (RR = 0.79, 95% CI: 0.64, 0.98) compared with NHWs, adjusted for confounders. CONCLUSIONS: Better survival after stroke in MAs is surprising considering their similar stroke subtype and severity compared with NHWs. Social or psychological factors, which may explain this difference, should be explored.

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PubMed2004

Family history of stroke among Mexican-American and non-Hispanic white patients with stroke and TIA: implications for the feasibility and design of stroke genetics research.

Family history of stroke may differ by ethnicity. This study examined the associations of ethnicity and stroke risk factors with family history of stroke using data from the Brain Attack Surveillance in Corpus Christi Project. A random sample of stroke/transient ischemic attack cases was interviewed about family history of stroke (n = 524). Thirty-six percent of the cases reported a family history of stroke, with 26% reporting a parental and 13% a sibling history. Compared to non-Hispanic whites (NHWs), Mexican-Americans (MAs) were two times (OR = 2.07; 95% CI: 1.09-3.95) more likely to have a sibling with stroke. More MAs (8.1%; 95% CI: 4.6-11.6) had living siblings with stroke compared to NHWs (1.9%; 95% CI: 0.1-3.8). Since MAs are more likely to have living siblings with stroke compared with NHWs, MAs may be a more feasible population for family stroke studies than predominantly white populations.

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PubMed2004

Excess stroke in Mexican Americans compared with non-Hispanic Whites: the Brain Attack Surveillance in Corpus Christi Project.

Mexican Americans are the largest subgroup of Hispanics, the largest minority population in the United States. Stroke is the leading cause of disability and third leading cause of death. The authors compared stroke incidence among Mexican Americans and non-Hispanic Whites in a population-based study. Stroke cases were ascertained in Nueces County, Texas, utilizing concomitant active and passive surveillance. Cases were validated on the basis of source documentation by board-certified neurologists masked to subjects' ethnicity. From January 2000 to December 2002, 2,350 cerebrovascular events occurred. Of the completed strokes, 53% were in Mexican Americans. The crude cumulative incidence was 168/10,000 in Mexican Americans and 136/10,000 in non-Hispanic Whites. Mexican Americans had a higher cumulative incidence for ischemic stroke (ages 45-59 years: risk ratio = 2.04, 95% confidence interval: 1.55, 2.69; ages 60-74 years: risk ratio = 1.58, 95% confidence interval: 1.31, 1.91; ages >or=75 years: risk ratio = 1.12, 95% confidence interval: 0.94, 1.32). Intracerebral hemorrhage was more common in Mexican Americans (age-adjusted risk ratio = 1.63, 95% confidence interval: 1.24, 2.16). The subarachnoid hemorrhage age-adjusted risk ratio was 1.57 (95% confidence interval: 0.86, 2.89). Mexican Americans experience a substantially greater ischemic stroke and intracerebral hemorrhage incidence compared with non-Hispanic Whites. As the Mexican-American population grows and ages, measures to target this population for stroke prevention are critical.

Age Distribution↗

PubMed2004

Stroke risk after transient ischemic attack in a population-based setting.

BACKGROUND AND PURPOSE: Stroke risk after transient ischemic attack (TIA) has not been examined in an ethnically diverse population-based community setting. The purpose of this study was to identify stroke risk among TIA patients in a population-based cerebrovascular disease surveillance project. METHODS: The Brain Attack Surveillance in Corpus Christi (BASIC) Project prospectively ascertains stroke and TIA cases in a geographically isolated Southeast Texas County. The community is approximately half Mexican American and half nonHispanic white. Cases are validated by board-certified neurologists using source documentation. Cumulative risk for stroke after TIA was determined using Kaplan-Meier estimates. Cox proportional hazards regression was used to test for associations between stroke risk after TIA and demographics, symptoms, risk factors, and history of stroke/TIA. RESULTS: BASIC identified 612 TIA cases between January 1, 2000, and December 31, 2002; 60.9% were female and 48.0% were Mexican American. Median age was 73.8 years. Stroke risk within 2 days, 7 days, 30 days, 90 days, and 12 months was 1.64%, 1.97%, 3.15%, 4.03%, and 7.27%, respectively. Stroke risk was not influenced by ethnicity, symptoms, or risk factors. CONCLUSIONS: Using a population-based design, we found that early stroke risk after TIA was less than previously reported in this bi-ethnic population of Mexican Americans and nonHispanic whites. Approximately half of the 90-day stroke risk after TIA occurred within 2 days.

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PubMed2004

Designing multi-ethnic stroke studies: the Brain Attack Surveillance in Corpus Christi (BASIC) project.

The Brain Attack Surveillance in Corpus Christi (BASIC) project is a population-based stroke study comparing Mexican Americans and non-Hispanic whites. Extensive effort is made to detect all patients regardless of ethnicity and ensure equal participation in the interview among both groups. We describe here the study's design and process evaluation with a focus on reducing bias in case ascertainment and participation. During the first 28 months of the project, 11,829 subjects were screened. Availability of neuroimaging did not differ by ethnicity (P=0.22), nor did confidence in the validated diagnosis of stroke (P=0.10). Participation rate in the interview also did not differ by ethnicity (P=0.92). There was excellent agreement of ethnic classification between chart abstraction and self-report (kappa=0.94, P<0.001). We conclude that multi-ethnic stroke comparison studies are feasible. Utilizing epidemiologic principles to design, recruit and analyze data are critical. Process evaluation to examine for sources of bias is important to study conduct.

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PubMed2003

Access to care, acculturation, and risk factors for stroke in Mexican Americans: the Brain Attack Surveillance in Corpus Christi (BASIC) project.

BACKGROUND AND PURPOSE: Mexican Americans are the largest subgroup of Hispanic Americans, now the most numerous US minority population. We compared access to care, acculturation, and biological risk factors among Mexican American and non-Hispanic white stroke patients and the general population. METHODS: The Brain Attack Surveillance in Corpus Christi project is a population-based stroke surveillance study conducted in southeast Texas. All stroke cases were ascertained through active and passive surveillance from January 2000 through April 2002 and compared with population estimates from a random-digit telephone survey. RESULTS: Compared with non-Hispanic white stroke patients (n=405), Mexican American stroke patients (n=403) were less likely to have graduated from high school (odds ratio [OR], 15.4; 95% confidence interval [CI], 10.6 to 22.4) and more likely to earn less than 20 000 dollars per year (OR, 6.5; 95% CI, 4.5 to 9.4). Mexican American stroke patients were more likely to have diabetes (OR, 2.7; 95% CI, 2.0 to 3.7) and less likely to have atrial fibrillation (OR, 0.5; 95% CI, 0.4 to 0.8). Compared with population estimates (n=719), stroke was associated with diabetes (Mexican Americans: OR, 3.6; 95% CI, 2.2 to 5.8; non-Hispanic whites: OR, 3.0; 95% CI, 1.7 to 5.5), hypertension (Mexican Americans: OR, 2.8; 95% CI, 1.8 to 4.3; non-Hispanic whites: OR, 3.3; 95% CI, 2.2 to 5.0), lower incomes (Mexican Americans: OR, 3.4; 95% CI, 2.1 to 5.4; non-Hispanic whites: OR, 3.0; 95% CI, 1.7 to 5.2), and lower educational attainment (Mexican Americans: OR, 5.1; 95% CI, 3.2 to 8.1; non-Hispanic whites: OR, 4.5; 95% CI, 2.2 to 9.3). CONCLUSIONS: Biological and social variables are associated with stroke to a similar extent in both Mexican Americans and non-Hispanic whites. Health behavior interventions for both populations may follow from this work. Stroke disparities between these populations may be explained only partially by differences in the prevalence of currently identified biological and social factors.

Acculturation↗

PubMed2003

Improving efficiency of stroke research: the Brain Attack Surveillance in Corpus Christi study.

We studied whether a computer algorithm or abstractor could diagnose stroke as well as a fellowship-trained stroke neurologist. As part of an ongoing prospective, community-based stroke surveillance project, a diagnostic algorithm was developed, and patients' neurologic signs and symptoms were collected in a computerized database. The abstractors were blinded to the results of this algorithm and were asked to verify whether the patient had a stroke. The separate results of the computer and abstractor were compared with the final diagnosis given by the blinded neurologist. From 1 January through 31 July 2000, 3418 cases were screened. The abstractors yielded sensitivity 91%, specificity 97%, positive predictive value (PPV) 85%, and negative predictive value (NPV) 99%. Three computer algorithms were evaluated. The sensitivities ranged from 83% to 96%, specificity ranged from 88% to 97%, PPV ranged from 54% to 81%, and NPV ranged from 97% to 99%. The use of computer verification or abstractors may obviate the need for physician stroke verification and may greatly improve study efficiency.

Algorithms↗

PubMed2002

Comparison of active and passive surveillance for cerebrovascular disease: The Brain Attack Surveillance in Corpus Christi (BASIC) Project.

To provide a scientific rationale for choosing an optimal stroke surveillance method, the authors compared active surveillance with passive surveillance. The methods involved ascertaining cerebrovascular events that occurred in Nueces County, Texas, during calendar year 2000. Active methods utilized screening of hospital and emergency department logs and routine visiting of hospital wards and out-of-hospital sources. Passive means relied on International Classification of Diseases, Ninth Revision (ICD-9), discharge codes for case ascertainment. Cases were validated by fellowship-trained stroke neurologists on the basis of published criteria. The results showed that, of the 6,236 events identified through both active and passive surveillance, 802 were validated to be cerebrovascular events. When passive surveillance alone was used, 209 (26.1%) cases were missed, including 73 (9.1%) cases involving hospital admission and 136 (17.0%) out-of-hospital strokes. Through active surveillance alone, 57 (7.1%) cases were missed. The positive predictive value of active surveillance was 12.2%. Among the 2,099 patients admitted to a hospital, passive surveillance using ICD-9 codes missed 73 cases of cerebrovascular disease and mistakenly included 222 noncases. There were 57 admitted hospital cases missed by active surveillance, including 13 not recognized because of human error. This study provided a quantitative means of assessing the utility of active and passive surveillance for cerebrovascular disease. More uniform surveillance methods would allow comparisons across studies and communities.

Cerebrovascular Disorders↗

PubMedDate not supplied

Use of death certificates to study ethnic-specific mortality.

OBJECTIVES: The Hispanic population in the United States represents more than 40 million individuals, with Mexican Americans (MA) as the largest subgroup. To assess the utility of death certificates and medical records as the source of race/ethnicity data for epidemiologic studies, we compared self-reported race/ ethnicity to race/ethnicity recorded on death certificates and medical records in a bi-ethnic, non-immigrant U.S. community with a significant MA population. METHODS: This study utilized data collected from a subset of 1,856 participants of the Brain Attack Surveillance in Corpus Christi (BASIC) project. In-person interviews were conducted to determine self-reported race/ethnicity. Of those interviewed, 480 subsequently expired. Using self-reported race/ethnicity as the gold standard, we determined percent agreement, sensitivity, and specificity of the death certificate and medical record. RESULTS: Of the 480 subjects, 259 self-reported their race/ethnicity as non-Hispanic white (NHW), 195 self-reported as MA, and 26 self-reported as non-Hispanic black. Median age was 78.5 years and 55.8% were female. Percent agreement between self-reported race/ethnicity and race/ethnicity recorded on the death certificate and medical record was 97.1% and 96.3% respectively. Five percent of MAs were misclassified as NHW on their death certificates and 3% on their medical records. CONCLUSIONS: Results indicated that Hispanic designation recorded on death certificates and medical records in this community was largely consistent with that of self-report. This study suggests that vital statistics data in non-immigrant U.S. Hispanic communities can be used with confidence to investigate ethnic-specific aspects of disease and mortality. Similar studies in other multi-racial communities should be conducted to confirm and generalize these results.

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