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Biomedical subjects

A S Kosinski

Publications and source records attributed to A S Kosinski.

At least 19 recordsLinked to original sources
PubMed2000

Targeting patients undergoing angioplasty for thrombus inhibition: a cost-effectiveness and decision support model.

BACKGROUND: In recent clinical trials, glycoprotein IIb/IIIa blockers have demonstrated effectiveness in preventing adverse events after angioplasty in high-risk patients. However, uncertainty exists regarding the cost-effective selection of patients to receive antiplatelet therapy. METHODS AND RESULTS: All 4962 patients at Emory University Hospitals who underwent coronary intervention procedures (n=6062) from 1993 to 1995 were studied. Multivariate models to predict death and the composite of death, Q-wave and non-Q-wave myocardial infarction, and emergency additional revascularization were developed. Hospital costs and professional costs were determined. A cost-effectiveness analysis with therapy targeted to high-risk patients was performed. If patients with a >5% probability of events received antiplatelet therapy that reduced events by 24% and cost $1000, 40.1% of patients would receive therapy; complications would be reduced from 6.39% to 5.37%, and cost would increase $261 from $10343 to $10604, or $25504 per event prevented. The marginal cost per event prevented by moving from a 7% to a 5% probability of an event cutoff would be $57 799. CONCLUSIONS: For high-risk patients, there may be cost savings; for low-risk patients, therapy may not be cost effective; and for patients in the midrange (between 5% and 7% probability of an adverse event), events may be prevented at an acceptable level of cost.

Angioplasty↗
PubMed2000

Eight-year mortality in the Emory Angioplasty versus Surgery Trial (EAST)

OBJECTIVES: To evaluate the long-term outcome of patients randomized to coronary bypass surgery or coronary angioplasty. BACKGROUND: The Emory Angioplasty versus Surgery Trial (EAST) is a single center randomized comparison of a strategy of initial coronary angioplasty (n = 198) or coronary bypass surgery (n = 194) for patients with multivessel coronary artery disease. The primary end point (death, myocardial infarction or a large ischemic defect at 3 years) was not different, and repeat revascularization was significantly greater in the angioplasty group. Subsequently, the National Heart, Lung and Blood Institute supported a five-year extension of the trial. METHODS: After the three year anniversary visit, annual questionnaires, telephone contact and examination of medical records were accomplished until death or the eight year anniversary in 100% of the patients surviving at 3 years. RESULTS: Survival at 8 years is 79.3% in the angioplasty group and 82.7% in the surgical group (p = 0.40). Patients with proximal left anterior descending stenosis and those with diabetes tended to have better late survival with surgical intervention although not reaching statistical significance. After the first 3 years, repeat interventions remained relatively equal for both treatment groups. CONCLUSIONS: Long-term survival is not significantly different between angioplasty and surgery, and late (three to eight year) revascularization procedures were infrequent. Patients without treated diabetes had similar survival in both groups.

Aged↗
PubMed1999

Prognostic value of thallium-201 single-photon emission computed tomography for patients with multivessel coronary artery disease after revascularization (the Emory Angioplasty versus Surgery Trial [EAST]).

The aim of this study was to investigate the relation between reversible thallium single-photon emission computed tomography (SPECT) myocardial perfusion defects at 1-year after revascularization and quantitative indexes in Emory Angioplasty versus Surgery Trial (EAST) and outcomes 3 years after revascularization in 336 patients. EAST was a randomized controlled trial assessing cardiac outcomes for angioplasty versus bypass surgery for patients with multivessel coronary artery disease. During this prospective trial, a substudy included the evaluation of the prognostic value of reversible defects on quantitative thallium SPECT. At 1-year after revascularization, 336 patients underwent SPECT thallium-201 stress myocardial perfusion and 3-hour delayed imaging. Subsequent events, percutaneous transluminal coronary angioplasty, coronary artery bypass graft surgery, myocardial infarction, and death, were recorded at 3 years. A stress-induced reversible thallium-201 defect was defined using a quantitative index of a reversibility score >30% and severity score >500. Reversible defects were observed more frequently in the percutaneous transluminal coronary angioplasty than in the coronary artery bypass graft surgery treatment groups (46% vs 27%, p <0.001). A total of 123 patients had stress-induced, reversible thallium defects and more events than patients with other perfusion results (freedom from all events was 81.3% vs 94% [p <0.001], and freedom from myocardial infarction and death 88.3% vs 95.5% [p = 0.031]). Quantitative thallium SPECT at 1 year after revascularization risk stratifies patients as to their likelihood of major cardiac outcomes.

Aged↗
PubMed1999

Evaluating the exposure and disease relationship with adjustment for different types of exposure misclassification: a regression approach.

Misclassification of exposure can lead to biased results in the epidemiologic research. Available methods accounting for misclassification often require the use of a gold standard or assume non-differential misclassification of exposure. We present a regression approach which can detect and account for different types of misclassification when estimating the exposure and disease relationship. This approach uses two imperfect measures of a dichotomous exposure and does not require a gold standard. Standard statistical packages with a logistic regression module can be used for estimation of parameters through the EM algorithm process. Two examples are used to illustrate the methodology.

Algorithms↗
PubMed1999

A regression model for multivariate random length data.

Multivariate random length data occur when we observe multiple measurements of a quantitative variable and the variable number of these measurements is also an observed outcome for each experimental unit. For example, for a patient with coronary artery disease, we may observe a number of lesions in that patient's coronary arteries, along with percentage of blockage of each lesion. Barnhart and Sampson first proposed the multiple population model to analyse multivariate random length data without covariates. This paper extends their approach to deal with multiple covariates. We propose a new multiple population regression model with covariates, and discuss the estimation issues. We analyse data from the TYPE II coronary intervention study to illustrate the methodology.

Cholestyramine Resin↗
PubMed1999

Economic impact of GPIIB/IIIA blockade after high-risk angioplasty: results from the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis.

OBJECTIVE: This study was conducted to assess the impact of GPIIb/IIIa blockade with tirofiban on costs during the initial hospitalization and at 30 days among patients undergoing high-risk coronary angioplasty. BACKGROUND: GPIIb/IIIa blockers are a new class of compounds that have been shown in clinical studies to prevent complications after high-risk angioplasty. METHODS: The RESTORE trial was a multinational, blinded placebo-controlled study of 2,197 patients randomized to tirofiban or placebo following coronary angioplasty. This economic assessment was a prospective substudy of the RESTORE trial, and included 1,920 patients enrolled in the U.S. Costs were estimated for the U.S. cohort based on their utilization of healthcare resources and on costs measured directly in 820 U.S. patients at 30 sites. RESULTS: There was a 36% difference in the rate of the composite event of death, myocardial infarction (MI) and revascularization at two days between tirofiban and placebo (8% vs. 12%, p = 0.002). This difference was attributed to a reduction in nonfatal MI, repeat angioplasty, coronary surgery and stent placement. These clinical benefits followed a similar trend at 30 days, with a 16% reduction in the composite event (p = 0.10). In-hospital cost, including professional and study drug costs, was $12,145 +/- 5,882 with placebo versus $12,230 +/- 5,527 with tirofiban (p = 0.75). The 30-day cost was $12,402 +/- 6,147 with placebo versus $12,446 +/- 5,814 with tirofiban (p = 0.87). CONCLUSIONS: Tirofiban has been shown to decrease in-hospital and possibly 30-day events after high-risk angioplasty. The beneficial clinical effects of tirofiban in high-risk patients can be achieved at no increased cost.

Adult↗
PubMed1999

A comparison of the Charlson comorbidity index derived from medical record data and administrative billing data.

The objective of this article is to compare the Charlson comorbidity index derived from medical record data (Chart Index) with the same index derived from billing data (ICD-9 Index) to determine how well each predicted inpatient and 30-day mortality, length of stay, and complications among Medicare beneficiaries hospitalized for carotid endarterectomy. Economic and time constraints have increased the need for risk adjusters derived from administrative data, yet few studies have compared these measures with those derived from chart review. Using logistic regression, the Chart Index was found to be a significant predictor of inpatient mortality, 30-day mortality, length of stay, and complications, after controlling for age, gender, and neurologic and medical risk factors (P values = 0.004, 0.056, 0.0001, and 0.042, respectively). The ICD-9 Index approached significance as a predictor of the outcomes (P values = 0.092, 0.100, 0.093, and 0.080, respectively). The Chart Index was shown to be superior to the ICD-9 Index within this patient sample.

Comorbidity↗
PubMed1998

Concomitant aortic and renal artery reconstruction in patients on an intensive antihypertensive medical regimen: long-term outcome.

A beneficial effect in blood pressure control is presumed for patients on an intensive preoperative antihypertensive regimen who undergo empiric renal revascularization. Nonetheless, a noticeable decline in surgical cure rates for hypertension has been recently observed in patients with generalized atherosclerosis. The outcome of patients on multiple preoperative antihypertensive agents who underwent combined aortic and renal artery reconstruction was reviewed. The study population comprised 43 patients who underwent concomitant renal artery and aortic reconstruction for atherosclerotic disease between 1983 and 1995 and who were taking two or more antihypertensive medications and had a serum creatinine of less than or equal to 1.7 mg/dL. Operative management included an aortic reconstruction with either unilateral (n = 22) or bilateral (n = 19) aortorenal bypass or renal endarterectomy (n = 2). Operative mortality was 4.7% (2 of 43). The estimated 5-yr probability of survival was 83% (95% C.I. 0.70, 0.99). Late follow-up data on blood pressure control were available for review in 32 patients at a median follow-up of 37 months. Hypertension was cured in 1 (3%) and improved in an additional 15 (47%) patients. The numbers of antihypertensive medications taken preoperatively (mean = 2.7) declined at late follow-up (mean = 1.6). Notably, the largest reduction was observed with beta blockers (p = 0.006), central sympatholytics (p = 0.041), and angiotensin converting enzyme (ACE) inhibitors (p = 0.052). The number of preoperative antihypertensive medications was not significantly related to survival or to blood pressure improvement. However, uncontrolled preoperative hypertension despite antihypertensive therapy was associated with a favorable blood pressure response to operation (p < 0.001). Patients on an intensive antihypertensive regimen can safely undergo concomitant renal artery and aortic reconstruction for the empiric management of hypertension. Poorly controlled preoperative hypertension in the presence of multiple antihypertensive agents is a favorable marker for improved postoperative blood pressure control.

Aged↗
PubMed1998

Angiogenesis as a predictor of survival after surgical resection for stage I non-small-cell lung cancer.

OBJECTIVES: Some patients with surgically resected stage I non-small-cell lung cancer eventually have metastatic disease. A histologic marker of metastatic potential and diminished survival for stage I non-small-cell lung cancer may distinguish this patient population. This study evaluates the degree of angiogenesis as a predictor of cancer-related death after operation for stage I non-small-cell lung cancer. METHODS: Demographic, surgical, and histopathologic data, including presence of vascular invasion, were reviewed for 106 patients with stage I non-small-cell lung cancer from 1985 through 1990. Visual quantitation of microvessels immunostained with factor VIII-related antigen and CD31 in 5 microm sections from the paraffin blocks of tissue defined rumor angiogenesis. RESULTS: Follow-up was 95.1% complete, mean 5.2 +/- 3.0 years. Lung cancer-related mortality rate was 24.4% at 5 years. Mean microvessel counts were 20.7 +/- 11.2 for FVIII and 29.6 +/- 18.1 for CD31. Univariate analysis revealed an FVIII count of at least 20 (p = 0.025) and blood vessel invasion (p = 0.017) to be significant predictors of disease-related death. After adjustment for other patient and tumor characteristics, multivariate Cox regression analysis found an FVIII count of at least 20 (hazard ratio 2.9) and blood vessel invasion (hazard ratio 3.7) to be significant independent correlates of lung cancer death (p = 0.018 and p = 0.011, respectively). CD31 quantitation did not predict survival on univariate or multivariate analyses and did not correlate strongly with FVIII quantitation (Spearman's rank correlation r = 0.19). CONCLUSIONS: This analysis reveals a significant association between tumor neovascularization and cancer-related mortality rate among patients with stage I non-small-cell lung cancer. Microvessel quantitation of FVIII, as an indicator of tumor angiogenesis and metastatic potential, may define a subset of patients with stage I non-small-cell lung cancer who could benefit from adjuvant therapy after surgical resection.

Adenocarcinoma↗
PubMed1998

Prospective, randomized trial comparing blood and oxygenated crystalloid cardioplegia in reoperative coronary artery bypass grafting.

OBJECTIVES: Reoperative coronary artery bypass grafting presents unique challenges for myocardial preservation. The purpose of this study was to compare oxygenated blood cardioplegia with oxygenated crystalloid cardioplegia during reoperative coronary artery bypass grafting using transesophageal echocardiography to assess regional wall motion of the left ventricle before and after cardiopulmonary bypass. METHODS: Sixty-one patients undergoing reoperative coronary artery bypass grafting were prospectively randomized to receive oxygenated blood cardioplegia or oxygenated crystalloid cardioplegia delivered with a combined antegrade-retrograde technique. Transgastric short axis views of the left ventricle were made with transesophageal echocardiography during the operation before cardiopulmonary bypass and immediately after cardiopulmonary bypass. Regional wall motion was graded by a blinded observer, and before cardiopulmonary bypass scores were compared with after cardiopulmonary bypass scores. RESULTS: No significant differences were found in the change in regional wall motion score from before cardiopulmonary bypass to after cardiopulmonary bypass between the blood and crystalloid cardioplegia groups. CONCLUSIONS: This study found blood and crystalloid cardioplegia to be equally efficacious for myocardial preservation during reoperative coronary artery bypass grafting.

Bicarbonates↗
PubMed1998

Power considerations when a continuous outcome variable is dichotomized.

An investigator can compare two groups with respect to a continuous outcome variable, Y, by comparing the means of Y or by collapsing that variable into categories. For example, antihypertensive treatments can be compared on the basis of blood pressure measurements, or on the basis of the proportions of patients with blood pressure in prespecified ranges. This report is concerned with the loss of power when inherently continuous variables are dichotomized. The report will focus on the power loss when a normally distributed variable with a known, common variance in each of two groups is dichotomized. Power is shown to depend on the relationship between the means of the two groups and the cutoff point, and it varies from negligible to substantial. The results will be applied to data from the Lovastatin Restenosis Trial. Initially the trial considered a dichotomous outcome (proportion of patients with elevated percent diameter stenosis), but the endpoint was later changed to the mean percent diameter stenosis. The modification in the design of the trial was well justified because the power loss was considerable when comparing proportions.

Algorithms↗
PubMed1997

Angioplasty or surgery for multivessel coronary artery disease: comparison of eligible registry and randomized patients in the EAST trial and influence of treatment selection on outcomes. Emory Angioplasty versus Surgery Trial Investigators.

The Emory Angioplasty versus Surgery Trial (EAST) showed that multivessel patients eligible for both percutaneous transluminal coronary angioplasty (PTCA) and coronary bypass surgery (CABG) had equivalent 3-year outcomes regarding survival, myocardial infarction, and major myocardial ischemia. Patients eligible for the trial who were not randomized because of physician or patient refusal were followed in a registry. This study compares the outcomes of the randomized and registry patients. Of the 842 eligible patients, 450 did not enter the trial. Their baseline features closely resembled those of the randomized patients and follow up was performed using the same methods. In the registry there was a bias toward selecting CABG in patients with 3-vessel disease (84%) and PTCA in patients with 2-vessel disease (54%). Three-year survival for the registry patients was 96.4%, which was better than the randomized patients, 93.4% (p = 0.044). Angina relief in the registry was equal for CABG and PTCA patients and was better for the PTCA registry (12.4%) than PTCA randomized patients (19.6%) (p = 0.079). Thus, the registry confirms that EAST is representative of all eligible patients and does not represent a low-risk subgroup. Since baseline differences were small, improved survival in the registry may be due to treatment selection. Physician judgment, even in patients judged appropriate for clinical trials, remains a potentially important predictor of outcomes.

Aged↗
PubMed1997

Tubal ligation and fatal ovarian cancer in a large prospective cohort study.

Several studies suggest that tubal sterilization may decrease the risk of ovarian cancer. Data from the Cancer Prevention Study II were analyzed to examine the relation between tubal ligation and ovarian cancer mortality in a large prospective study. A total of 396,114 women who had not had hysterectomies and who had no prior history of cancer (except nonmelanoma skin cancer) were followed prospectively for approximately 9 years from 1982 to 1991. During this time, 799 ovarian cancer deaths were observed. Tubal ligation was significantly associated with a decreased risk of ovarian cancer mortality in an age- and race-adjusted Cox proportional hazards model (hazard ratio (HR) = 0.64, 95% confidence interval (CI) 0.42-0.96), and the results were essentially unchanged when controlling for potential ovarian cancer risk factors (HR = 0.68, 95% CI 0.45-1.03). The protective effect appeared to be greater in the first 20 years after the procedure (HR = 0.49, 95% CI 0.24-0.99) than later (HR = 0.80, 95% CI 0.48-1.34). No interactions between ever having had a tubal ligation and other covariates were observed. These data suggest that tubal ligation reduces the risk of fatal ovarian cancer.

Adult↗
PubMed1997

Late survival after valve operation in patients with left ventricular dysfunction.

BACKGROUND: Left ventricular dysfunction is a predictor of hospital mortality after cardiac valve operation. We evaluated late survival in a large cohort of these patients. METHODS: From 1980 to 1993, 257 patients with a preoperative ejection fraction of 0.40 or less underwent aortic (n = 177), mitral (n = 72), or combined (n = 8) valve operation, with or without concomitant coronary artery bypass grafting. RESULTS: Hospital mortality was 12.5%. Follow-up was 98% complete. Logistic regression analysis showed that an ejection fraction of less than 0.30, mitral regurgitation, concomitant coronary artery bypass grafting, emergency operation, and reoperation were independent correlates of hospital mortality (all at p < 0.05). Kaplan-Meier survival curves of the 220 hospital survivors showed a 65% 5-year survival. Multivariate analysis revealed preoperative use of diuretics, male sex, reoperation, age exceeding 60 years, and aortic regurgitation to be independent predictors of poor late outcome (all at p < 0.05). CONCLUSIONS: The liability of left ventricular dysfunction with regard to diminished long-term survival is not completely reversed by valve operation. If operation is not performed before left ventricular dysfunction develops, postoperative medical treatment of these dilated, remodeled ventricles should be considered.

Adolescent↗
PubMed1996

Is there a bias against performing coronary revascularization in women?

This study compares referral to coronary revascularization after diagnostic cardiac catheterization in 8,133 women and 25,785 men. Although gender played a role, angiographic severity of coronary disease was the most important determinant of the selection of patients for revascularization.

Age Distribution↗
PubMed1996

Effectiveness of revascularization in the Emory angioplasty versus surgery trial. A randomized comparison of coronary angioplasty with bypass surgery.

BACKGROUND: The Emory Angioplasty Versus Surgery Trial (EAST) was designed to determine whether percutaneous transluminal coronary angioplasty (PTCA) is as effective as coronary artery bypass graft surgery (CABG) in restoring arterial perfusion capacity in eligible patients with multivessel disease. METHODS AND RESULTS: Of 392 patients in EAST, 198 were randomized to PTCA and 194 to CABG. Index lesions (2.7 +/- 1.0 per patient) were those with > or = 50% stenosis judged treatable by both angioplasty and surgery. Coronary segments jeopardized by these index lesions were designated as index segments (4.4 +/- 1.4 per patient). Percent stenosis was measured by quantitative angiography at the point of greatest obstruction in the main perfusion path of each index segment. The EAST primary arteriographic end point was the percent of a patient's index segments with < 50% stenosis in the main perfusion pathways at 1 and 3 years. At baseline, the percent of index segments for which revascularization was attempted was 85% for PTCA and 98% for CABG (P < .0001). At 1 year, PTCA patients had a smaller percentage of successfully revascularized index segments than CABG patients (59% versus 88%, P < .001). At 3 years, the findings were similar but less striking (70% versus 87%, P < .001). When only "high-priority" index segments (2.1 +/- 1.6 per patient) were considered, baseline attempts were comparable (96% versus 99%, P = NS); despite this, CABG remained more successful at 1 (64% versus 93%, P < .001) and 3 (76% versus 89%, P < .01) years. However, the mean percent of index segments free of severe stenosis (> or = 70%) did not differ between PTCA and CABG patients at 3 years (93% versus 95%, P = NS). Furthermore, the frequency of patients with all index segments free of severe stenosis did not differ between the two groups at 1 (76% versus 83%, P = NS) or 3 (82% for both PTCA and CABG) years. CONCLUSIONS: In patients with multivessel disease, index segment revascularization was more complete with CABG than PTCA at both 1 and 3 years. However, when the physiological priority of the target lesion and the measured severity of the residual stenosis are taken into account, the advantage of CABG becomes less significant or nonsignificant. This may, in part, explain why these two strategies did not differ in terms of the EAST primary clinical end points over 3 years.

Aged↗