Biomedical subjects

C Burchfiel

Publications and source records attributed to C Burchfiel.

6 recordsLinked to original sources

PubMed1994

Pulmonary function decline and 17-year total mortality: the Honolulu Heart Program.

The Honolulu Heart Program continues to follow a cohort of Japanese-American men initially aged 45-68 years, of whom 4,000 had three acceptable measurements of forced expiratory volume in 1 second (FEV1) between 1965 and 1974 and were free of cardiovascular disease and cancer. The 6-year rate of change (slope) in FEV1 was calculated using a within-person linear regression method. Men were divided into tertiles based on the rate of change in FEV1. During 17 subsequent years of follow-up, 796 deaths occurred. The tertile with the greatest rate of decline in FEV1 (mean, -61 ml/year) had the highest age-adjusted total mortality rate (17.3/1,000 person-years), followed by rates of 13.2 for the middle tertile (mean, -25 ml/year) and 11.0 for men with the smallest change in FEV1 (mean, +9 ml/year) (test for trend, p < 0.0001). Using the Cox model, comparing the tertile with the smallest change in FEV1 as a reference group with the tertile with the greatest decline in FEV1, and after adjusting for age, hypertension, smoking, body mass index, alcohol intake, diabetes mellitus, and cholesterol, the authors found the relative risk (RR) for total mortality to be 1.48 (95% confidence interval (CI) 1.24-1.77). After stratification by smoking status, this association remained significant for past smokers (RR = 1.79, 95% CI 1.31-2.14), as well as for the low, < or = 42 (RR = 1.46, 95% CI 1.05-2.03), and high, > 42 (RR = 1.56, 95% CI 1.20-2.02), pack-year groups. An increased risk was also present for current smokers (RR = 1.29), but it was of borderline significance (p = 0.08). No association was found among never smokers. These data suggest that the rate of decline in FEV1 is a predictor of total mortality among smokers.

Aged↗

PubMed1990

Initial report of the Veterans Administration Preoperative Risk Assessment Study for Cardiac Surgery.

This study was authorized by the Department of Veterans Affairs to improve the quality assurance of cardiac surgery by assessing preoperative risk factors and relating them to operative mortality. Data were received on 10,480 patients over a 2-year period. Preoperative risk variables were subjected to univariate and multivariate logistic regression analyses. Significant variables for coronary artery bypass grafting after logistic regression analysis in order of importance are previous cardiac operation, priority of operation, New York Heart Association functional class, peripheral vascular disease, age, pulmonary rales, current diuretic use, and chronic obstructive pulmonary disease. For patients undergoing valve or other cardiac operations with or without coronary artery bypass grafting, those variables found to be significant after multivariate logistic regression analysis are priority of operation; age; peripheral vascular disease; great vessel repair; all other except aortic valve replacement, mitral valve replacement, and great vessel repair; mitral valve replacement; and cardiomegaly. By identifying these current risk factors and the coefficients from the multivariate stepwise logistic regression analysis, expected mortality can be calculated. We propose that the ratio of observed to expected mortality is a better measure of quality of care than unadjusted mortality.

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PubMed1990

Identification of patients at greatest risk for developing major complications at cardiac surgery.

As part of a prospective program to use risk-adjusted outcome (operative mortality and morbidity) as a measure of quality of care, we have analyzed perioperative complication data in 10,634 patients representing 73% of all patients undergoing cardiac surgery requiring cardiopulmonary bypass at Veterans Administration medical centers between April 1, 1987, and March 31, 1989. One or more complications occurred in 15% of patients undergoing coronary artery bypass grafting, and in 24% of patients undergoing valve and other cardiac surgery. Patients experiencing one or more complications had an eightfold to 10-fold increase in operative mortality compared with patients with no perioperative complications. The most frequent complication was requirement for mechanical ventilation for at least 48 hours occurring in 8% of patients undergoing coronary artery bypass and in 15% of patients undergoing valve and other cardiac surgery; 24-25% of these patients died within 30 days of surgery or as a direct result of a surgical complication. Previous heart surgery was a strong predictor of development of one or more complications in both groups of patients, being associated with an adjusted relative risk of 1.6-2.0. Other important predictors in both surgical groups were surgical priority, older age, peripheral vascular disease, and higher serum creatinine. Although a number of preoperative risk factors could be identified for the development of renal failure, low cardiac output, and requirement for prolonged mechanical support, few risk factors could be identified for the development of mediastinitis and reoperation for bleeding. This observation suggests that mediastinitis and reoperation for bleeding are more likely the result of technical factors rather than patient-related risk factors.

Cardiac Surgical Procedures↗

PubMed1988

Six month postoperative hemodynamics of the Hancock heterograft and the Björk-Shiley prosthesis: results of a Veterans Administration cooperative prospective randomized trial.

In a Veterans Administration Cooperative Study involving 13 medical centers, 575 patients undergoing single valve replacement were prospectively randomized to receive either the standard Björk-Shiley prosthesis or the Hancock porcine heterograft (with a modified orifice for sizes 23 and smaller). The hemodynamic data in the 268 patients who underwent cardiac catheterization an average of 6 months (range 3 to 12) postoperatively are reported. Statistical analyses were performed on valve sizes 23, 25 and 27 in the aortic position, and 29, 31 and 33 in the mitral position. A wide variation was observed in mean pressure gradient and calculated orifice area in both valve types within all sizes in both the aortic and the mitral positions. In the aortic position, the Björk-Shiley prosthesis tended to have a lower pressure gradient and larger calculated orifice area than the Hancock heterograft, but the differences in gradient between the two valve types were significant only in the larger-sized valves. The difference in calculated area between the two valve types was not significant within each valve size. In the mitral position, there were no differences in gradient and calculated orifice area between the two types of prostheses. The postoperative cardiac index, regurgitant volume, pulmonary artery systolic and mean pressures, left ventricular end-diastolic pressure, left ventricular ejection fraction and left ventricular end-diastolic volume index did not differ in patients receiving the Björk-Shiley prosthesis from values in patients receiving the Hancock heterograft. Hence, the overall hemodynamic performance of both types of valves is remarkably similar. The choice between these two prostheses should, therefore, be governed not by the hemodynamic performance, but by other factors such as valve durability, risk of anticoagulation and incidence of valve-related complications.

Aortic Valve↗

PubMed1987

Clinical, hemodynamic, and angiographic predictors of operative mortality in patients undergoing single valve replacement. Veterans Administration Cooperative Study on Valvular Heart Disease.

Preoperative characteristics of 964 patients in the Veterans Administration Cooperative Study on Valvular Heart Disease undergoing single valve replacement were examined to determine predictors of operative mortality. The operative mortality rate was 8.3% in 661 patients having isolated aortic valve disease and 7.5% in 239 patients having isolated mitral valve disease, but 12.5% in 64 patients with multivalve disease undergoing single valve replacement. For the aortic valve replacement subgroup, three-vessel coronary artery disease, left ventricular systolic pressure, prior cardiac operation, body surface area, and cardiac index were related to operative mortality. In the mitral valve replacement group, there was a strong association of operative mortality with advanced age, exertional dizziness, reduced cardiac index, left ventricular contraction grade, ST segment depression on the resting electrocardiogram, and pleural effusion. The risk of operative death for an individual patient undergoing aortic or mitral valve replacement may be estimated with the use of independent risk factors.

Adult↗

PubMedDate not supplied

Arsenic exposure, smoking, and respiratory cancer in copper smelter workers.

A report by Lee and Fraumeni in 1969 linked exposure to arsenic and other contaminants to a threefold excess of respiratory cancer among 8,047 employees at the Anaconda copper smelter. We established vital status through December 1977 for a sample of 1,800 men from the original cohort. Average arsenic concentrations were estimated for each smelter department based on industrial hygiene measurements made from 1943 to 1965. Departments with similar concentrations were combined into four categories of exposure: 1) low (less than 100 micrograms/m3), 2) medium (100-499 micrograms/m3), 3) high (500-4,999 micrograms/m3) and 4) very high (greater than or equal to 5,000 micrograms/m3). Three indices of individual arsenic exposure were developed: time-weighted average, 30-day ceiling, and cumulative. Exposures to sulfur dioxide and asbestos were also examined. Smoking habits were obtained by questionnaire. Mortality was compared to that of men in the State of Montana using the modified lifetable method. A clear dose-response relationship between arsenic exposure and respiratory cancer was demonstrated. Men in the highest exposure category had a sevenfold excess. Those in the low and medium categories had a risk close to that expected. Ceiling arsenic exposure appeared to be more important than did time-weighted average exposure. Sulfur dioxide and asbestos did not appear to be important in the excess of respiratory cancer, although sulfur dioxide and arsenic exposures could not be separated completely. Smoking did not appear to be as important as arsenic exposure. Our findings suggest that had men worked only in departments with low or medium arsenic exposures (i.e., less than 500 micrograms/m3) there would have been little excess respiratory cancer. Since the estimates of arsenic exposure were based on department averages rather than on concentrations for individual jobs, these results must be interpreted with caution.

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