A randomized, controlled trial to teach middle school children to recognize stroke and call 911: the kids identifying and defeating stroke project

BACKGROUND AND PURPOSE

Underutilization of acute stroke therapy is driven by delay to hospital arrival. We present the primary results of a pilot, randomized, controlled trial to encourage calling 911 for witnessed stroke among middle school children and their parents.

METHODS

This project occurred in Corpus Christi, an urban Texas community of 325,000. Three intervention and 3 control schools were randomly selected. The intervention contained 12 hours of classroom instruction divided among sixth, seventh, and eighth grades. Parents were educated indirectly through homework assignments. Two-sample t tests were used to compare pretest and posttest responses.

RESULTS

Domain 1 test questions involved stroke pathophysiology. Intervention students improved from 29% to 34% correct; control students changed from 28% to 25%. Domain 2 test questions involved stroke symptom knowledge. Intervention school students changed from 28% correct to 43%; control school students answered 25% correctly on the pretest and 29% on the posttest. Domain 3 test questions involved what to do for witnessed stroke. Intervention school students answered 36% of questions correctly on the pretest and 54% correctly on the posttest, whereas control students changed from 32% correct to 34%. A comparison of change in the mean proportion correct over time between intervention and control students was P<0.001 for each of the 3 individual domains. A poor parental response rate impaired the ability to assess parental improvement.

CONCLUSIONS

A scientific, theory-based, educational intervention can potentially improve intent to call 911 for stroke among middle school children. A different mechanism is needed to effectively diffuse the curriculum to parents.

A study to assess the effects of a broad-spectrum immune modulatory therapy on mortality and morbidity in patients with chronic heart failure: the ACCLAIM trial rationale and design

BACKGROUND

Evidence has accumulated regarding the importance of inflammatory mediators in the development and progression of heart failure (HF). Although targeted anticytokine treatment strategies, specifically antitumour necrosis factor-alpha, have yielded disappointing results, this may simply reflect the redundancy of the cytokine cascade and the fact that antitumour necrosis factor-alpha therapies do not stimulate increased activity of the anti-inflammatory arm of the immune system. Ex vivo exposure of autologous blood to controlled oxidative stress and subsequent intramuscular administration is a device-based procedure shown in experimental studies to have a broad-spectrum effect on a number of immune mediators. These studies have demonstrated that this approach downregulates inflammatory cytokines, whereas several anti-inflammatory cytokines are increased. In a feasibility study of 73 patients with moderate to severe HF, active therapy (versus placebo) had a significant benefit on both mortality and hospitalization, and was not associated with adverse hemodynamic or metabolic effects.

METHODS

The Advanced Chronic heart failure CLinical Assessment of Immune Modulation therapy (ACCLAIM) trial is a multicentre, randomized, double-blind, placebo-controlled clinical trial of New York Heart Association functional class II to IV chronic HF patients with left ventricular ejection fraction of 30% or less. Enrolling approximately 2400 subjects at 177 sites, the primary end point of the study was the cumulative incidence (time to first event) of the combined end point of total mortality or hospitalization for cardiovascular causes. The study was completed in late 2005, when 701 primary end point events had occurred and all patients had been treated for six months.

CONCLUSIONS

If the ACCLAIM trial confirms earlier results, this approach represents a novel nonpharmacological treatment for HF that targets a pathogenic mechanism contributing to progression of this syndrome not addressed by current therapies.

Kids Identifying and Defeating Stroke (KIDS): design of a school-based intervention to improve stroke awareness

BACKGROUND

We describe the design and baseline data of an educational intervention targeting predominantly Mexican American middle school students and their parents in an effort to improve stroke awareness. Increasing awareness in this group may increase the number of patients eligible for acute stroke treatment by encouraging emergency medical services (EMS) activation.

METHODS

This is a prospective, randomized study in which six middle schools were randomly assigned to receive a stroke education program or the standard health class. Primary outcome measures are the percentage of students and parents who recognize stroke symptoms and express the intent to activate EMS upon recognition of these findings.

RESULTS

A total of 547 students (271 control, 276 intervention) and 484 parents (231 control, 253 intervention) have been enrolled. Pretests were administered. The intervention has been successfully carried out in the parent and student cohorts over a three-year period. Posttests and persistence test results are pending.

CONCLUSION

Implementing a school-based stroke education initiative is feasible. Followup testing will demonstrate whether this educational initiative translates into a measurable and persistent improvement in stroke knowledge and behavioral intent to activate EMS upon recognition of stroke symptoms.

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.

A Multinational Study to Establish the Value of Early Adenosine Technetium-99m Sestamibi Myocardial Perfusion Imaging in Identifying a Low-Risk Group for Early Hospital Discharge After Acute Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine whether gated adenosine Tc-99m sestamibi single-photon emission computed tomography (ADSPECT) could accurately define risk and thereby guide therapeutic decision making in stable survivors of acute myocardial infarction (AMI).

BACKGROUND

Controversy continues as to the role of noninvasive stress imaging in stratifying risk early after AMI.

METHODS

The INSPIRE (Adenosine Sestamibi Post-Infarction Evaluation) trial is a prospective multicenter trial which enrolled 728 clinically stable survivors of AMI who had gated ADSPECT within 10 days of hospital admission and subsequent 1-year follow-up. Event rates were assessed within prospectively defined INSPIRE risk groups based on the adenosine-induced left ventricular perfusion defect size, extent of ischemia, and ejection fraction.

RESULTS

Total cardiac events/death and reinfarction significantly increased within each INSPIRE risk group from low (5.4%, 1.8%), to intermediate (14%, 9.2%), to high (18.6%, 11.6%) (p < 0.01). Event rates at 1 year were lowest in patients with the smallest perfusion defects but progressively increased when defect size exceeded 20% (p < 0.0001). The perfusion results significantly improved risk stratification beyond that provided by clinical and ejection fraction variables. The low-risk INSPIRE group, comprising one-third of all enrolled patients, had a shorter hospital stay with lower associated costs compared with the higher-risk groups (p < 0.001).

CONCLUSIONS

Gated ADSPECT performed early after AMI can accurately identify a sizeable low-risk group who have a <2% death and reinfarction rate at 1 year. Identifying these low-risk patients for early hospital discharge may improve utilization of health care resources at considerable cost savings.

An Initial Strategy of Intensive Medical Therapy Is Comparable to That of Coronary Revascularization for Suppression of Scintigraphic Ischemia in High-Risk But Stable Survivors of Acute Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine the relative benefit of intensive medical therapy compared with coronary revascularization for suppressing scintigraphic ischemia.

BACKGROUND

Although medical therapies can reduce myocardial ischemia and improve patient survival after acute myocardial infarction, the relative benefit of medical therapy versus coronary revascularization for reducing ischemia is unknown.

METHODS

A prospective randomized trial in 205 stable survivors of acute myocardial infarction was made to define the relative efficacy of an intensive medical therapy strategy versus coronary revascularization for suppressing scintigraphic ischemia as assessed by serial gated adenosine Tc-99m sestamibi myocardial perfusion tomography. All patients at baseline had large total (> or =20%) and ischemic (> or =10%) adenosine-induced left ventricular perfusion defects and an ejection fraction > or =35%. Imaging was performed during 1 to 10 days of hospital admission and repeated in an identical fashion after optimization of therapy. Patients randomized to either strategy had similar baseline demographic and scintigraphic characteristics.

RESULTS

Both intensive medical therapy and coronary revascularization induced significant but comparable reductions in total (-16.2 +/- 10% vs. -17.8 +/- 12%; p = NS) and ischemic (-15 +/- 9% vs. -16.2 +/- 9%; p = NS) perfusion defect sizes. Likewise, a similar percentage of patients randomized to medical therapy versus coronary revascularization had suppression of adenosine-induced ischemia (80% vs. 81%; p = NS).

CONCLUSIONS

Sequential adenosine sestamibi myocardial perfusion tomography can effectively monitor changes in scintigraphic ischemia after anti-ischemic medical or coronary revascularization therapy. A strategy of intensive medical therapy is comparable to coronary revascularization for suppressing ischemia in stable patients after acute infarction who have preserved LV function.

Argatroban tPA Stroke Study

BACKGROUND

The benefit of intravenous recombinant tissue plasminogen activator (rtPA) in acute stroke is linked to clot lysis and artery recanalization. Argatroban is a direct thrombin inhibitor that safely augments the benefit of rtPA in animal stroke models. There are no human data on this combination.

DESIGN

We report the first phase of the Argatroban tPA Stroke Study, an ongoing prospective, open-label, dose-escalation, safety and activity study of argatroban and rtPA in patients with ischemic stroke. The primary outcome was incidence of intracerebral hemorrhage; secondary outcome, complete recanalization at 2 hours. After standard-dose intravenous rtPA administration, a 100-mug/kg bolus of argatroban followed by infusion of 1 mug/kg per minute for 48 hours was adjusted to a target partial thromboplastin time of 1.75 times that of the control group.

RESULTS

Fifteen patients (including 10 men) were enrolled, with a mean +/- SD age of 61 +/- 13 years. All patients had middle cerebral artery occlusions. Baseline median National Institute of Health Stroke Scale score was 14 (range, 4-25). The mean +/- SD time from symptom onset to argatroban bolus administration was 172 +/- 53 minutes. Symptomatic intracerebral hemorrhage occurred in 2 patients, including 1 with parenchymal hemorrhage type 2. Asymptomatic bleeding occurred in 1 patient and there was 1 death. Recanalization was complete in 6 patients and partial in another 4, and reocclusion occurred in 3 within 2 hours of rtPA bolus administration.

CONCLUSION

The safety of low-dose argatroban combined with intravenous rtPA may be within acceptable limits, and its efficacy for producing fast and complete recanalization is promising, but a larger cohort of patients is required to confirm these preliminary observations.

Dependence, hyper-dependence and hypothesis testing in clinical trials

While investigators designing clinical trials face the important issue of endpoint selection, an equally troublesome concern can be the a priori selection of the endpoint analysis. In this latter circumstance, there may be only one endpoint of interest in the clinical trial, but several competing endpoint analyses are available (e.g., an analysis of the endpoint that is adjusted for clinical center versus an analysis that is adjusted for geographic region versus an unadjusted analysis). An example that demonstrates the unsatisfactory conclusions that ambiguous choices can produce is offered. A procedure utilizing conditional probability is provided that permits the conservation of type I error when the investigators have one endpoint and several worthy competitor endpoint analyses that are each prospectively identified and carried out at the trial's conclusion. When the high levels of dependence among these analyses are taken into account, it is possible to carry out the hypothesis tests in a way that 1) provides practicable type I error levels for each analysis, and 2) conserves the familywise type I error. In circumstances in which the endpoint and all members of the family of analyses are selected during the design phase of the trial, this procedure provides confirmatory conclusions as opposed to exploratory findings.

A scoring system for ascertainment of incident stroke; the Risk Index Score (RISc)

OBJECTIVES

The main objective of this study was to develop and validate a computer-based statistical algorithm that could be translated into a simple scoring system in order to ascertain incident stroke cases using hospital admission medical records data.

METHODS

The Risk Index Score (RISc) algorithm was developed using data collected prospectively by the Brain Attack Surveillance in Corpus Christi (BASIC) project, 2000. The validity of RISc was evaluated by estimating the concordance of scoring system stroke ascertainment to stroke ascertainment by physician and/or abstractor review of hospital admission records.

RESULTS

RISc was developed on 1718 randomly selected patients (training set) and then statistically validated on an independent sample of 858 patients (validation set). A multivariable logistic model was used to develop RISc and subsequently evaluated by goodness-of-fit and receiver operating characteristic (ROC) analyses. The higher the value of RISc, the higher the patient's risk of potential stroke. The study showed RISc was well calibrated and discriminated those who had potential stroke from those that did not on initial screening.

CONCLUSION

In this study we developed and validated a rapid, easy, efficient, and accurate method to ascertain incident stroke cases from routine hospital admission records for epidemiologic investigations. Validation of this scoring system was achieved statistically; however, clinical validation in a community hospital setting is warranted.

Prognostic use of echocardiography 1 year after a myocardial infarction

BACKGROUND

Left ventricular (LV) and right ventricular (RV) function are known predictors of morbidity and mortality after an acute myocardial infarction (MI). However, the prognostic use of a late evaluation of cardiac function after an MI remains unclear.

METHODS

We analyzed echocardiograms obtained 1 year after MI in patients with LV dysfunction at baseline (ejection fraction [EF] < or = 40%) from 291 patients enrolled in the SAVE echocardiographic substudy who did not develop heart failure (HF) or a recurrent MI during this first year. Left ventricular EF and RV fractional area change were assessed.

RESULTS

After a median follow-up of 22 months after the 1-year echocardiogram, a low LVEF (< 30%) at 1 year was associated with an increased risk of death and/or HF (hazards ratio [HR] 2.7, 95% CI 1.3-5.3). Presence of RV dysfunction was also associated with an increased risk of death (HR 8.9, 95% CI 3.5-22.1), development of HF (HR 7.1, 95% CI 3.4-15.0), and the composite end point of death or HF (HR 7.6, 95% CI 4.1-14.2). In multivariate analyses, both low LVEF and RV dysfunction remained independently predictive of the composite end point of death or HF. Patients with biventricular dysfunction were at the greatest risk of death and/or HF (HR 19.4, 95% CI 8.2-46.0) in follow-up.

CONCLUSIONS

In a stable population of survivors of MI, impaired LV and RV function at 1 year after MI are independently and additively predictive of increased risk of HF or death.

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.

Ischemic stroke subtypes among Mexican Americans and non-Hispanic whites: the BASIC Project

Ischemic stroke subtype distribution was compared between Mexican Americans (MAs) and non-Hispanic whites (NHWs) in a community-based stroke surveillance study in Nueces County, TX. There was no difference in the distribution of stroke subtype by ethnicity (p = 0.19). There was a similar proportion of small-vessel and large-artery strokes between the two ethnic groups (p = 0.32). Differences in stroke rates among MAs and NHWs are not explained by the distribution of ischemic stroke subtypes.

Chronic Kidney Disease, Cardiovascular Risk, and Response to Angiotensin-Converting Enzyme Inhibition After Myocardial Infarction

Background— Persons with end-stage renal disease and those with lesser degrees of chronic kidney disease (CKD) have an increased risk of death after myocardial infarction (MI) that is not fully explained by associated comorbidities. Future cardiovascular event rates and the relative response to therapy in persons with mild to moderate CKD are not well characterized.

Methods and Results— We calculated the estimated glomerular filtration rate (eGFR) using the 4-variable Modification of Diet in Renal Disease method in 2183 Survival And Ventricular Enlargement (SAVE) trial subjects. SAVE randomized post-MI subjects (3 to 16 days after MI) with left ventricular ejection fraction ≤40% and serum creatinine <2.5 mg/dL to captopril or placebo. Cox proportional hazards models were used to evaluate the relative hazard rates for death and cardiovascular events associated with reduced eGFR. Subjects with reduced eGFR were older and had more extensive comorbidities. The multivariable adjusted risk ratio for total mortality associated with reduced eGFR from 60 to 74, 45 to 59, and <45 mL · min −1 · 1.73 m −2 (compared with eGFR ≥75 mL · min −1 · 1.73 m −2 ) was 1.11 (0.86 to 1.42), 1.24 (0.96 to 1.60) and 1.81 (1.32 to 2.48), respectively ( P for trend =0.001). Similar adjusted trends were present for CV mortality ( P =0.001), recurrent MI ( P =0.017), and the combined CV mortality and morbidity outcome ( P =0.002). The absolute benefit of captopril tended to be greater in subjects with CKD: 12.4 versus 5.5 CV events prevented per 100 subjects with (n=719) and without (n=1464) CKD, respectively.

Conclusions— CKD was associated with a heightened risk for all major CV events after MI, particularly among subjects with an estimated glomerular filtration rate <45 mL · min −1 · 1.73 m −2 . Randomization to captopril resulted in a reduction of CV events irrespective of baseline kidney function.

Ultrasound-enhanced systemic thrombolysis for acute ischemic stroke

BACKGROUND

Transcranial Doppler ultrasonography that is aimed at residual obstructive intracranial blood flow may help expose thrombi to tissue plasminogen activator (t-PA). Our objective was to determine whether ultrasonography can safely enhance the thrombolytic activity of t-PA.

METHODS

We treated all patients who had acute ischemic stroke due to occlusion of the middle cerebral artery with intravenous t-PA within three hours after the onset of symptoms. The patients were randomly assigned to receive continuous 2-MHz transcranial Doppler ultrasonography (the target group) or placebo (the control group). The primary combined end point was complete recanalization as assessed by transcranial Doppler ultrasonography or dramatic clinical recovery. Secondary end points included recovery at 24 hours, a favorable outcome at three months, and death at three months.

RESULTS

A total of 126 patients were randomly assigned to receive continuous ultrasonography (63 patients) or placebo (63 patients). Symptomatic intracerebral hemorrhage occurred in three patients in the target group and in three in the control group. Complete recanalization or dramatic clinical recovery within two hours after the administration of a t-PA bolus occurred in 31 patients in the target group (49 percent), as compared with 19 patients in the control group (30 percent; P=0.03). Twenty-four hours after treatment of the patients eligible for follow-up, 24 in the target group (44 percent) and 21 in the control group (40 percent) had dramatic clinical recovery (P=0.7). At three months, 22 of 53 patients in the target group who were eligible for follow-up analysis (42 percent) and 14 of 49 in the control group (29 percent) had favorable outcomes (as indicated by a score of 0 to 1 on the modified Rankin scale) (P=0.20).

CONCLUSIONS

In patients with acute ischemic stroke, continuous transcranial Doppler augments t-PA-induced arterial recanalization, with a nonsignificant trend toward an increased rate of recovery from stroke, as compared with placebo.

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.

Alcohol consumption and prognosis in patients with left ventricular systolic dysfunction after a myocardial infarction

OBJECTIVES

We assessed the influence of alcohol intake on the development of symptomatic heart failure (HF) in patients with left ventricular (LV) dysfunction after a myocardial infarction (MI).

BACKGROUND

In contrast to protection from coronary heart disease, alcohol consumption has been linked to cardiodepressant effects and has been considered contraindicated in patients with HF.

METHODS

The Survival And Ventricular Enlargement (SAVE) trial randomized 2231 patients with a LV ejection fraction (EF) <40% following MI to an angiotensin-converting enzyme inhibitor or placebo. Patients were classified as nondrinkers, light-to-moderate drinkers (1 to 10 drinks/week), or heavy drinkers (>10 drinks/week) based on alcohol consumption reported at baseline. The primary outcome was hospitalization for HF or need for an open-label angiotensin-converting enzyme inhibitor. Analyses were repeated using alcohol consumption reported three months after MI.

RESULTS

Nondrinkers were older and had more comorbidities than light-to-moderate and heavy drinkers. In univariate analyses, baseline light-to-moderate alcohol intake was associated with a lower incidence of HF compared with nondrinkers (hazard ratio [HR] 0.71; 95% confidence interval [CI] 0.57 to 0.87), whereas heavy drinking was not (HR 0.91; 95% CI 0.67 to 1.23). After adjustment for baseline differences, light-to-moderate baseline alcohol consumption no longer significantly influenced the development of HF (light-to-moderate drinkers HR 0.93; 95% CI 0.75 to 1.17; heavy drinkers HR 1.25; 95% CI 0.91 to 1.72). Alcohol consumption reported three months after the MI similarly did not modify the risk of adverse outcome.

CONCLUSIONS

In patients with LV dysfunction after an MI, light-to-moderate alcohol intake either at baseline or following MI did not alter the risk for the development of HF requiring hospitalization or an open-label angiotensin-converting enzyme inhibitor.

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.

Access to Care, Acculturation, and Risk Factors for Stroke in Mexican Americans

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 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.

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.

Perils of the random experiment

Most medical research is executed on samples selected from large populations. Nevertheless, health care researchers often blur the difference between interpreting sample-based research and evaluating research that included the entire population of interest. This is an implication-critical distinction; in population research, every result applies to the population (because the entire population was included in the analysis), although only a few results from sample-based research can be extended to the population at large. Treating every result from sample-based research as if that result applies to the population is misleading. Using nonmathematic terminology, this article develops the reason for the differences in the implications of these two research perspectives. In sample-based research, the best indicators of which results should be extended from the sample to the population are the presence of (1) a prospective plan for that experiment; and (2) the execution of the experiment according to that plan (concordant execution). The absence of these two features produces execution and analysis decisions based on the incoming data stream-the hallmark of the random experiment. In this latter paradigm, allowing the data to influence the execution and analysis decisions renders the usual estimates of effect size, standard errors, confidence intervals, and P values untrustworthy. Readers of clinical trial results must be vigilant for nonprotocol-driven research and understand that the results from these programs are at best exploratory and cannot be used to answer scientific questions.

Sample size for biomarker studies: more subjects or more measurements per subject?

PURPOSE

In molecular epidemiologic studies, optimizing the use of available biological specimens while minimizing the cost is always a challenge. This is particularly true in pilot studies, which often have limited funding and involve small numbers of biological samples too small for assessment of recently developed biomarkers.

METHODS

In this study we examined several statistical approaches for determining how many experimental subjects to use in a biomarker study and how many repeated measurements to make on each sample, given specific funding considerations and the correlated nature of the repeated measurements.

RESULTS

A molecular epidemiology study of DNA repair and aging in basal cell carcinoma was used to illustrate the application of the statistical methods proposed.

CONCLUSIONS

Our methods extend traditional designs on biomarker studies with repeated measurements to including funding constraints.

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.

The fragility of cardiovascular clinical trial results

BACKGROUND

Clinical trials that have their prospective analysis plan altered are difficult to interpret.

METHODS AND RESULTS

After providing 4 examples of problematic trial results that have had their findings reversed, the necessity of a fixed research protocol is developed. Investigators generally wish to extend the results from their research sample to the larger population; however, this delicate extension is complicated by the presence of sampling error. No computational or statistical tools can remove sampling error--the most that researchers can do is to provide to the medical and regulatory communities a measure of the distorting effect that sampling error can produce. Investigators accomplish this by providing an estimate of how likely it is that the population produced a misleading sample for them to study. However, studies in which the data determine the analysis plan damage these estimators. When they are damaged, these estimators produce untrustworthy assessments of the degree to which the study results reflect the population findings.

CONCLUSIONS

The way to avoid these complications is to design the experiment carefully, then carefully execute the experiment as it was designed.

Right ventricular dysfunction and risk of heart failure and mortality after myocardial infarction

OBJECTIVES

The aim of this study was to determine the prognostic value of right ventricular (RV) function in patients after a myocardial infarction (MI).

BACKGROUND

Right ventricular function has been shown to predict exercise capacity, autonomic imbalance and survival in patients with advanced heart failure (HF).

METHODS

Two-dimensional echocardiograms were obtained in 416 patients with left ventricular (LV) dysfunction (ejection fraction [LVEF] < or = 40%) from the Survival And Ventricular Enlargement (SAVE) echocardiographic substudy (mean 11.1 +/- 3.2 days post infarction). Right ventricular function from the apical four-chamber view, assessed as the percent change in the cavity area from end diastole to end systole (fractional area change [FAC]), was related to clinical outcome.

RESULTS

Right ventricular function correlated only weakly with the LVEF (r = 0.12, p = 0.013). On univariate analyses, the RV FAC was a predictor of mortality, cardiovascular mortality and HF (p < 0.0001 for all) but not recurrent MI. After adjusting for age, gender, diabetes mellitus, hypertension, previous MI, LVEF, infarct size, cigarette smoking and treatment assignment, RV function remained an independent predictor of total mortality, cardiovascular mortality and HF. Each 5% decrease in the RV FAC was associated with a 16% increased odds of cardiovascular mortality (95% confidence interval 4.3% to 29.2%; p = 0.006).

CONCLUSIONS

Right ventricular function is an independent predictor of death and the development of HF in patients with LV dysfunction after MI.