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Biomedical subjects

J F Toole

Publications and source records attributed to J F Toole.

At least 37 records · Page 2Linked to original sources
PubMed1997

Disability in US presidents report. Recommendations and commentaries by the Working Group. The Working Group on Presidential Disability.

If the president of the United States must decide within minutes how to respond to a dire emergency, its citizens expect him or her to be mentally competent and to act wisely. Because the presidency of the United States is now the world's most powerful office, should its incumbent become even temporarily unable to exercise good judgment, the consequences for the world could be unimaginably far-reaching.

Persons with Disabilities↗
PubMed1997

The delay in reporting symptoms of carotid artery stenosis in an at-risk population. The Asymptomatic Carotid Atherosclerosis Study experience: a statement of concern regarding watchful waiting.

OBJECTIVE: To examine whether patients in the Asymptomatic Carotid Atherosclerosis Study reported symptoms of cerebral and retinal ischemia promptly to the investigating team. DESIGN: Cohort study within the Asymptomatic Carotid Atherosclerosis Study, a prospective, randomized, multicenter clinical trial, with a median follow-up time of 2.7 years. SETTING: Thirty-nine clinical sites across the United States and Canada. PATIENTS: Patients with asymptomatic carotid artery stenosis (> or = 60% reduction in diameter) who experienced either a transient ischemic attack (TIA) (n = 115) or stroke (n = 127) during the follow-up period, as verified by an external committee. MAIN OUTCOME MEASURE: Proportion of patients who reported cerebrovascular symptoms to a study nurse or physician within 3 days of occurrence. RESULTS: Thirty-seven patients (32.2%) experiencing TIA and 57 (44.9%) experiencing stroke reported symptoms to the study staff within 3 days of onset. For TIA, there was a statistically significant inverse association between prompt reporting and the amount of time a patient was enrolled in the study before the event occurred (48% with TIA occurring within 6 months vs 9% with TIA after year 3; P = .04). For stroke, there was a statistically significant association between prompt reporting and treatment arm (56% for the surgical vs 38% for the medical group; P = .05). For either TIA or stroke, none of the other factors examined were significantly associated with prompt reporting. CONCLUSIONS: Despite extensive education and reinforcement, fewer than 40% of all first events were reported within 3 days and fewer than 25% were reported in less than 24 hours. Frequent outpatient evaluation of high-risk patients and careful review of symptoms is necessary to determine when asymptomatic carotid artery stenosis has become symptomatic to offer appropriate forms of therapy.

Adult↗
PubMed1997

Validation of the ACAS TIA/stroke algorithm.

BACKGROUND AND PURPOSE: An easily administered questionnaire and algorithm classifying transient ischemic attacks (TIAs) or strokes, and also their distribution, could be invaluable for identifying endpoints in epidemiologic studies or clinical trials of prevention and therapy of cerebral ischemia. The Asymptomatic Carotid Atherosclerosis Study (ACAS) devised a symptom-based questionnaire and algorithm for detecting events in the trial. The purpose of this study was to determine sensitivity, specificity, and agreement rates of the questionnaire and algorithm against diagnoses of a panel of cerebrovascular disease authorities. METHODS: Three hundred eighty-one men and women at eight medical centers reported symptoms of stroke, TIA, or other neurologic illness. The questionnaire was administered by trained interviewers and the responses were analyzed using the algorithm. A standardized neurologic examination was performed by a neurologist. Data were submitted to two or more external reviewers. Sensitivity, specificity, and the kappa statistic (kappa) were used to evaluate the relationship between the algorithm and the external reviewers' diagnosis. RESULTS: Of the 381 reviews, 196 were diagnosed as TIA or stroke by the external panel. The algorithm's agreement with the diagnosis of TIA or stroke was 80.1%, and kappa was 0.60. Sensitivity was 87.8%, and specificity was 71.9%. CONCLUSION: While statistical agreement rates depend on the method of sample selection, the algorithm has a high agreement with an external panel of experts and is a sensitive tool for event detection. The lower specificity indicates that careful neurologic evaluation may be required to confirm or refute events identified by the screening algorithm.

Adult↗
PubMed1996

Self-reported transient ischemic attack and stroke symptoms: methods and baseline prevalence. The ARIC Study, 1987-1989.

As part of the Atherosclerosis Risk in Communities (ARIC) Study assessment of the etiology and sequelae of atherosclerosis, a standardized questionnaire on transient ischemic attack (TIA) and nonfatal stroke and a computerized diagnostic algorithm simulating clinical reasoning were developed and tested at the four ARIC field centers: Forsyth County, North Carolina; Minneapolis, Minnesota; Jackson, Mississippi; and Washington County, Maryland. The diagnostic algorithm used participant responses to a series of questions about six neurologic trigger symptoms to identify symptoms of TIA or stroke and their vascular distribution. Among 12,205 ARIO participants reporting their lifetime occurrence of one or more symptoms probably due to cerebrovascular causes, nearly half (47%) reported the sudden onset of at least one symptom sometime prior to their ARIC examination. Of those with at least one symptom, only 12.9% were classified by the computer algorithm as having symptoms of TIA or stroke. Dizziness/loss of balance was the most frequently reported symptom (36%); 1.2% of these persons were classified by the algorithm as having a TIA/stroke event. Positive symptoms of speech dysfunction were classified most often (77.%) as being symptoms of TIA or stroke. Symptoms suggesting TIA were reported more frequently than symptoms suggesting stroke by both sexes. TIA or stroke-like phenomena were more frequent (p < 0.001) in females (7%) than in males (5%) and increased with age in both sexes (p = 0.13 for females; p = 0.02 for males). In Forsyth County, TIA and stroke symptoms were greater in African Americans than in Caucasians (p = 0.05, controlling for sex). The association of algorithmically defined symptoms of TIA or stroke with traditional cerebrovascular risk factors is the subject of a companion paper.

Algorithms↗
PubMed1996

Association of transient ischemic attack/stroke symptoms assessed by standardized questionnaire and algorithm with cerebrovascular risk factors and carotid artery wall thickness. The ARIC Study, 1987-1989.

The baseline examination (1987-1989) for the Atherosclerosis Risk in Communities (ARIC) Study was conducted in 15,792 free-living residents aged 45-64 years in four geographically dispersed US communities. A questionnaire on symptoms of transient ischemic attack (TIA) and stroke was evaluated by computer algorithm for 12,205 of these participants. Data were also collected on lipoprotein levels, hemostasis, hematology, anthropometry, blood pressure, medical history, lifestyle, socioeconomic status, and medication use. Noninvasive high resolution B-mode ultrasonographic imaging was used to determine carotid arterial intimal-medial wall thickness (IMT). The cross-sectional relation between the prevalence of TIA/stroke symptoms and putative risk factors was assessed by logistic regression, controlling for age and community. Odds ratios for TIA/stroke symptoms were significantly elevated (p < or = 0.01) for diabetes mellitus, current smoking, hypertension, lower levels of education, income, and work activity, and higher levels of lipoprotein(a), IMT, hemostasis factor VIII, and von Willebrand factor. However, the relations with education and carotid IMT were not present for black Americans. In whites, the relations of TIA/stroke symptoms to IMT were nonlinear. Only at extreme levels of IMT were symptoms substantially more frequent: For example, men with an IMT greater than 1.17 mm or women with an IMT greater than 0.85 mm had approximately twice the odds of having positive TIA/stroke symptoms as those with lower IMTs. The authors plan in future analyses to address the issue prospectively, as well as to examine the relation with magnetic resonance imaging-defined outcomes and clinically defined incident stroke.

Algorithms↗
PubMed1996

Surgical results: a justification of the surgeon selection process for the ACAS trial. The ACAS Investigators.

PURPOSE: The selection of surgeons to participate in a prospective randomized trial comparing the efficacy of a surgical method with medical management is critically important because it will have a direct impact on the outcome of the study and the future use of the operation. We report the success of the method used for selecting surgeons who participated in the Asymptomatic Carotid Atherosclerosis Study (ACAS) by examining the surgical morbidity and mortality rates and the outcome of the study. METHODS: A Surgical Management Committee established criteria for auditing surgeons who wished to participate in the study. The parameters included a minimum performance of at least 12 carotid endarterectomies (CEA) per year and an audit of each surgeon's last 50 consecutive CEAs with required documentation of a combined neurologic morbidity and mortality rate of <3.0% for asymptomatic patients and <5.0% for all indications including symptomatic patients. RESULTS: As of February 1991, 164 surgeons from 48 medical centers applied for ACAS participation. One hundred seventeen were approved, and their aggregate experience of 5641 operations yielded a combined neurologic morbidity and mortality rate of 2.3% for asymptomatic and symptomatic patients combined. The morbidity and mortality rate for CEA on asymptomatic patients was 1.7%. These surgeons, plus those recruited after February 1991, became investigators in the ACAS trial and were responsible for the surgical care of 825 patients who were randomized to the surgical arm. Seven hundred twenty-four patients actually underwent CEA. One patient (0.14%) died and ten patients (1.38%) had strokes within the 30-day perioperative interval, for a combined stroke or death incidence of 1.52%. The 5-year stroke event rate in the surgical group (including perioperative morbidity and mortality rates) was 5.1%. compared with 11% of patients treated medically, yielding a relative risk reduction of 53% in favor of surgery (p=0.004). CONCLUSIONS: A method for selecting surgeons for participation in the ACAS trial was successful in providing low perioperative morbidity and mortality rates. This materially influenced the outcome of the study in favor of CEA.

Arteriosclerosis↗
PubMed1996

Comparison of centralized versus "site-based" measurement of angiographic stenosis for eligibility in the asymptomatic carotid atherosclerosis study.

RATIONALE AND OBJECTIVES: The authors determine the reliability of centralized versus noncentralized (site-based) measurement of angiographic stenosis of patients enrolled into the multicenter, prospective, Asymptomatic Carotid Atherosclerosis Study by angiographic studies. METHODS: Percent agreements and correlations of 244 masked and prospectively interpreted angiograms were calculated for comparison of centralized and noncentralized readers measuring the percent carotid stenosis from the same angiographic studies. Univariate summary statistics for differences in percent stenoses were calculated for these readings. RESULTS: Agreement between readings were 88.5% and 91.8% with kappa statistics of 0.77 and 0.73 for > or = 60% and > or = 80% stenosis, respectively, for comparison of 33 centers to the designated central reader. Comparison between the designated central reader and a second central reader derived percent agreements of 85.0% and 86.5% with kappa statistics of 0.69 and 0.41 for > or = 60% and > or = 80% stenoses, respectively, for arteries selected from the original group. Hence, agreement was slightly better between the enrolling centers and the designated central reader than between the two central readers. CONCLUSIONS: Both centralized and noncentralized (site-based) methods of angiographic measurement of stenosis are equally reliable for large, prospective, masked, multicenter trials when quality control measures are instituted to ensure uniform application of eligibility criteria.

Angiography↗
PubMed1996

An approach for the use of Doppler ultrasound as a screening tool for hemodynamically significant stenosis (despite heterogeneity of Doppler performance). A multicenter experience. Asymptomatic Carotid Atherosclerosis Study Investigators.

BACKGROUND AND PURPOSE: The Asymptomatic Carotid Atherosclerosis Study (ACAS) Doppler validation study assessed the performance of individual Doppler machines across a spectrum of laboratories. We attempted to establish a threshold specific to individual machines to predict angiographically defined hemodynamic stenosis. The reliability of these Doppler ultrasound criteria was prospectively and independently evaluated among patients screened with ultrasound in the ACAS trial. METHODS: Regression techniques were used to establish the relationship between Doppler velocity and percent stenosis by angiography for 63 specific Doppler machines. This relationship was used to establish a Doppler threshold to provide a 90% positive predictive value (PPV) of a 60% stenosis by angiography. The sensitivity of each Doppler machine to detect a 60% stenosis (at the 90% PPV threshold) was estimated. The efficacy of these Doppler thresholds was then prospectively evaluated by calculating the PPV among ACAS participants eligible by ultrasound. RESULTS: Of the 63 machines, 13 (21%) had an excellent sensitivity (80%+) at 90% PPV. In 32 devices (51%) only a marginal sensitivity (50% to 80%) could be achieved. In 9 devices (14%) the sensitivity was poor (0% to 50%), and in 9 (14%) no threshold could be established. Despite the heterogeneity of Doppler performance, the standardization program worked as designed in the ACAS trial. Of 825 surgical patients, 399 were eligible by Doppler and 395 subsequently underwent angiography. Of these, 32 (8.1%; 95% confidence interval, 5.4% to 10.8%) did not have hemodynamically significant stenosis by arteriography, a proportion nonsignificantly lower than the planned 10% by the PPV. CONCLUSIONS: The performance of Doppler ultrasound was highly variable. This suggests that Doppler performance is likely overstated in the literature, but specific devices may perform satisfactorily to detect individuals with hemodynamically significant stenosis. Because performance differs substantially among devices, local investigators are strongly urged to maintain local standardization series. With such standardization, ultrasound performance is sufficient for admission to clinical trials and as the is sufficient for admission to clinical trials and as the basis for carotid surgery. However, without quality control many ultrasound machines are not adequate to accurately predict the degree of carotid stenosis and should not be the only test to decide whether surgery is warranted.

Angiography↗
PubMed1996

An analysis of perioperative surgical mortality and morbidity in the asymptomatic carotid atherosclerosis study. ACAS Investigators. Asymptomatic Carotid Atherosclerosis Study.

BACKGROUND AND PURPOSE: Our aim was to determine the perioperative morbidity and mortality rates of patients in the surgical arm of the multi-institutional, prospective, randomized Asymptomatic Carotid Atherosclerosis Study (ACAS). METHODS: Of 828 patients with carotid stenosis of 60% or more randomized to the surgical arm of ACAS, 721 underwent carotid endarterectomy (CEA). To qualify for participation, surgeons were required to have performed at least 12 CEAs per year with a combined neurological morbidity and mortality rate no greater than 3% for asymptomatic patients and 5% for symptomatic patients. Clinical centers had to demonstrate arteriographic morbidity less than 1% and mortality less than 0.1% per year. Primary events were stroke and death in the period between randomization and 30 days after surgery; secondary events were transient ischemic attack and myocardial infarction occurring in the same period. RESULTS: Of the 721 patients who underwent CEA, 1 died and 10 others had strokes within 30 days (1.5%). Of the 415 who underwent arteriography after randomization but before CEA, 5 (1.2%) suffered transient ischemic attack or stroke caused by arteriography. Thus, a nearly equal risk of stroke was associated with both CEA and carotid arteriography. In addition, 6 transient ischemic attacks and 3 myocardial infarctions could be directly linked to CEA, for a total CEA event rate of 2.6%. CONCLUSIONS: Patients with asymptomatic internal carotid artery stenosis exceeding 60% reduction in diameter who are acceptable candidates for elective operation may be considered for CEA if the combined arteriographic and surgical complication rates are 3% or less.

Anesthesia↗
PubMed1996

Presence and severity of cerebral white matter lesions and hypertension, its treatment, and its control. The ARIC Study. Atherosclerosis Risk in Communities Study.

BACKGROUND AND PURPOSE: White matter lesions (WML) may result from cerebral hypoperfusion or ischemia. We investigated the association of WML with blood pressure, hypertension, and its treatment and control. METHODS: A random sample of 1920 participants aged 55 to 72 years in the Atherosclerosis Risk in Communities Study (ARIC) was examined. Spin-density 1.5-T MRI scan images were coded from 0 for normal to 9 for most severe WML. Hypertension was defined as systolic or diastolic pressure > or = 140/90 mm Hg or use of antihypertensive medication. RESULTS: The percentages of persons with WML grades 0 through 2 and 3 through 9, respectively, were as follow: normotensive, 92.4% and 7.6%, versus all hypertensive subjects, 83% and 17% (P < .001); and treated controlled hypertensive, 86% and 14%, versus treated uncontrolled hypertensive subjects, 76% and 24% (P = .003). Multivariable adjusted odds ratios (95% confidence intervals) for WML grade > or = 3 relative to normotensive subjects was 2.34 (1.71 to 3.20) for all hypertensives, 1.99 (1.19 to 3.08) for untreated hypertensives, 1.94 (1.32 to 2.85) for treated controlled hypertensives, and 3.40 (2.30 to 5.03) for treated uncontrolled hypertensives. After additional adjustment for hypertension duration, treatment, and control status, the odds ratios (95% confidence intervals) for a 1 SD increase of systolic and diastolic blood pressure were 1.43 (1.11 to 1.85) and 1.16 (0.94 to 1.43), respectively. CONCLUSIONS: Hypertension is associated with increased odds of WML, and treated uncontrolled hypertensive subjects have greater odds of WML than those with treated controlled hypertension. The data suggest that the level of blood pressure, especially systolic blood pressure, is related to WML, additional to the effects of categorically defined hypertension and its treatment and control status.

Aged↗
PubMed1996

[Indications for endarterectomy in asymptomatic stenoses of the internal or common carotid artery--results of the North American ACAS Study].

OBJECTIVE: To determine the effect of endarterectomy on the primary prevention of ischemic stroke in patients with asymptomatic carotid artery stenosis. METHODS: In a prospective, randomized, multicenter trial 1659 patients with asymptomatic carotid stenosis of 60% or more were studied in two treatment arms (endarterectomy: n = 825; medical therapy: n = 834). Endpoints were: (1) ischemic stroke in the vascular territory of the study artery, (2) any perioperative stroke or any perioperative death. RESULTS: The Kaplan-Meier 5-year-risk estimation showed a relative risk reduction of 53% (confidence interval: 22%-72%) for patients in the surgical arm. The combined perioperative morbidity and mortality rate was 2.3%. CONCLUSION: Endarterectomy of asymptomatic carotid artery stenosis performed with a perioperative complication rate of less than 3% reduces the 5-year risk of ipsilateral stroke.

Adult↗
PubMed1995

Medical compared with surgical treatment of asymptomatic carotid artery stenosis.

The Asymptomatic Carotid Atherosclerosis Study (ACAS) results suggest that carotid endarterectomy combined with aspirin and risk factor reduction is superior to aspirin and risk factor reduction is superior to aspirin and risk factor reduction alone in preventing ipsilateral stroke in asymptomatic patients with diameter stenosis of the carotid artery of 60% or more. The absolute risk reduction over 5 years conferred by surgical therapy is modest (5.9%) compared with the risk reduction conferred by surgical therapy for symptomatic carotid disease but compares favorably with the degree of stroke prevention shown for antihypertensive therapy in the elderly. For prevention of stroke in women and for prevention of major stroke, the ACAS results favoring surgery did not reach statistical significance. The combined arteriographic and perioperative surgery-related mortality and stroke rates achieved by the carefully selected surgical teams was low (2.3%). Accordingly, carotid endarterectomy can be recommended for preventing stroke in the setting of hemodynamically significant stenosis when the arteriographic and surgical complication rates can be kept low.

Aspirin↗