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Biomedical subjects

R A Kronmal

Publications and source records attributed to R A Kronmal.

At least 73 records · Page 4Linked to original sources
PubMed1991

The Cardiovascular Health Study: design and rationale.

The Cardiovascular Health Study (CHS) is a population-based, longitudinal study of coronary heart disease and stroke in adults aged 65 years and older. The main objective of the study is to identify factors related to the onset and course of coronary heart disease and stroke. CHS is designed to determine the importance of conventional cardiovascular disease (CVD) risk factors in older adults, and to identify new risk factors in this age group, especially those that may be protective and modifiable. The study design called for enrollment of 1250 men and women in each of four communities: Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania. Eligible participants were sampled from Medicare eligibility lists in each area. Extensive physical and laboratory evaluations were performed at baseline to identify the presence and severity of CVD risk factors such as hypertension, hypercholesterolemia and glucose intolerance; subclinical disease such as carotid artery atherosclerosis, left ventricular enlargement, and transient ischemia; and clinically overt CVD. These examinations in CHS permit evaluation of CVD risk factors in older adults, particularly in groups previously under-represented in epidemiologic studies, such as women and the very old. The first of two examination cycles began in June 1989. A second comprehensive examination will be repeated three years later. Periodic interim contacts are scheduled to ascertain and verify the incidence of CVD events, the frequency of recurrent events, and the sequellae of CVD.

Aged↗
PubMed1990

Coronary Artery Surgery Study (CASS): comparability of 10 year survival in randomized and randomizable patients.

The Coronary Artery Surgery Study (CASS) includes 780 patients with mild or moderate stable angina pectoris or asymptomatic survivors of a myocardial infarction who were randomized to either medical or surgical therapy and 1,319 patients who were eligible for randomization but were not randomized (randomizable patients). There were no substantial aggregate differences observed in any of the survival comparisons after 10 years of follow-up study between the randomized and randomizable patients assigned to the medical (79% versus 80%) or surgical (82% versus 81%) groups or in patient subgroups stratified according to coronary artery disease extent and left ventricular ejection fraction. Cox regression analyses were done with independent variables known to be predictors of survival, including surgical versus medical therapy and randomized versus randomizable group, to test the null hypothesis of a mortality difference between medical versus surgical assignment according to group assignment (randomized versus randomizable). In no case did the initial group category enter as a significant predictor of survival. The results in the randomizable group reinforce those in the randomized group with respect to the medical versus surgical comparison. Two subgroups are identified with a significant surgical advantage: 1) patients with proximal left anterior descending coronary artery stenosis greater than or equal to 70% and an ejection fraction less than 0.50, and 2) patients with three vessel coronary artery disease and an ejection fraction less than 0.50. In both groups, coronary bypass surgery had a statistically significant beneficial effect on survival (p less than 0.05). After a decade of follow-up, the CASS randomizable patients confirm conclusions reached on the basis of the CASS randomized trial.

Angina Pectoris↗
PubMed1990

Risk ratios and risk differences in estimating the effect of risk factors for cardiovascular disease in the elderly.

This article reviews the nature of the effects of hypertension, smoking and cholesterol on the incidence of cardiovascular disease and emphasizes how these effects vary by age. In the Methods section, we discuss briefly the concepts of additive and multiplicative statistical models as tools for summarizing data. In the results section, we summarize available data on the association between incident stroke and coronary heart disease in the elderly and each of these major risk factors. The traditional multiplicative model parsimoniously characterizes the individual and joint effects of age and high blood pressure in terms of risk ratios; but, for smoking and cholesterol, an additive model appears to be the most parsimonious. We discuss the consequences of these observations for the study and prevention of cardiovascular disease in the elderly.

Adult↗
PubMed1989

Interannual variation of the incidence of Haemophilus influenzae type b meningitis.

We conducted a population-based retrospective cohort study to define the annual age-specific incidence of Haemophilus influenzae type b meningitis for birth to 5-year-old residents of King County, Washington, from January 1977 through December 1986. We found naturally occurring wide interannual variations in incidence. The standard deviations of the age-specific incidence during the eight years before the introduction of H influenzae vaccine varied from 26% to 115% of the mean. If short-term changes in incidence were used to assess the efficacy of an H influenzae vaccine (which is less than 100% efficacious and not administered to all susceptible children), the conclusions could be erroneous. To avoid this bias, long-term cohort studies, case/control studies using concurrent controls, or large clinical trials are better choices. We found no significant change in overall incidence during the ten-year study period.

Age Factors↗
PubMed1989

Anomalous coronary arteries: location, degree of atherosclerosis and effect on survival--a report from the Coronary Artery Surgery Study.

Limited information is available about clinical presentation, degree of atherosclerosis and effect on overall survival in a large series of patients with coronary artery anomalies. From the National Heart, Lung, and Blood Institute Multicenter Coronary Artery Surgery Study (CASS), detailed coding of coronary angiograms was available in 24,959 patients. Of these patients, 73 (0.3%) had major coronary artery anomalies: 70 had one coronary anomaly and 3 had two coronary anomalies. The most common anomaly involved the circumflex coronary artery (60%). In 69% of these, the circumflex artery arose from a separate ostium in the right coronary sinus, and in 31% it originated as a branch of the right coronary artery. The most common anomalous course was anterior or posterior to the great vessels but not between the great vessels. The major exception to this finding was an anomalous right coronary artery; 7 of 15 such arteries coursed between the great vessels. Anomalous circumflex coronary arteries had a significantly greater degree of stenosis than that in nonanomalous arteries in age- and gender-matched control patients (p = 0.02). Despite this difference, at 7 years there was no significant difference in survival by location or degree of stenosis in the anomalous artery.

Adult↗
PubMed1989

The impact of Haemophilus influenzae type b meningitis on nutritional status.

We investigated the immediate impact and long-term effects of Haemophilus influenzae type b meningitis on nutritional status and growth in 111 children. Mean weight change during 10 d of hospitalization was a loss of less than 1%. Follow-up median weight-for-height percentiles increased after admission (p less than 0.01). Percentile values were as follows: admission, 45th; 1 mo, 60th; 3 mo, 60th; and 6 mo, 68th. Forty-three percent of the cases were greater than 75th percentile of weight-for-height at 6 mo after disease. An additional follow-up assessment of weight-for-height indicated that 43% of a representative sample subset of 49 were still obese 1.17-5.5 y after disease. Significant differences in median concentrations of serum prealbumin were found between days 1 (128 mg/L) and 5 (199 mg/L, p less than 0.0001) and days 5 and 10 (214 mg/L, p less than 0.02). Median erythrocyte glutathione reductase activity coefficients increased between days 1 (1.16) and 5 (1.20, p less than 0.01). The mean free erythrocyte protoporphyrin-heme ratio increased between days 5 (10.78 X 10(-6)) and 10 (14.22 X 10(-6), p less than 0.01). We conclude that there were transient adverse changes in nutritional status. Obesity appears to occur after disease.

Acute Disease↗
PubMed1989

Anemia during Haemophilus influenzae type b meningitis: lack of an effect of chloramphenicol.

We sought to determine whether chloramphenicol would worsen or mitigate the anemia associated with Haemophilus influenzae type b meningitis if administered in doses which produce 'therapeutic' serum concentrations. Seventy-four cases of H. influenzae meningitis were stratified by chloramphenicol cumulative doses (mg/kg body weight) of less than 300 and greater than 300. There was no significant difference in the decrease in blood hemoglobin concentration or in the increase in the FEP:Heme ratio between the two study groups. Plasma iron and transferrin saturation values indicated iron deficiency at days 1 and 5 of hospitalization; by day 10 mean values were within the normal range. These data suggest that H. influenzae type b meningitis, not chloramphenicol therapy in the presence of monitoring is causing the observed anemia.

Anemia↗
PubMed1988

Beneficial six-year outcome of smoking cessation in older men and women with coronary artery disease. Results from the CASS registry.

We investigated the effects of cigarette smoking and cessation of smoking in a cohort of 1893 men and women from the Coronary Artery Surgery Study (CASS) registry who were 55 years of age or older and had angiographically documented coronary artery disease. The six-year mortality rate was greater among continuing smokers (n = 1086) than among those who quit smoking during the year before enrollment in the study and abstained throughout the study (n = 807) (relative risk, 1.7 [95 percent confidence limits, 1.4, 2.0]). Continuing smokers were also at higher risk of either myocardial infarction or death (1.5 [1.2, 1.7]). There was no diminution of the beneficial effect with increasing age. The relative risks of death were 1.7 (1.4, 2.1) and 1.6 (1.1, 2.3) for the groups 55 to 64 years old and 65 or older, respectively, and 1.6 (1.4, 1.9) for comparable subgroups among CASS subjects 35 to 54 years of age. When subjects were arrayed according to risk quartile, the benefits of smoking cessation were greatest in those at moderate risk. We conclude that smoking cessation lessens the risk of death or myocardial infarction in older as well as younger persons with coronary artery disease.

Adult↗
PubMed1988

Prevalence and significance of atrial fibrillation in coronary artery disease (CASS Registry).

Estimates of the prevalence of atrial fibrillation (AF) in patients with coronary artery disease have varied from "frequent" to less than 2%. Data on 18,343 patients with angiographically demonstrated CAD in the Coronary Artery Surgery Study (CASS) registry were reviewed and AF was found to be present in 116 (0.6%) patients. The presence of AF was positively associated with the following clinical and angiographic variables: older age, sex (male), mitral regurgitation and functional impairment due to congestive heart failure. The number of diseased coronary arteries was negatively related to the presence of AF. Atrial fibrillation was an independent predictor of survival and its presence doubled the estimated risk over those patients without AF.

Adult↗
PubMed1987

Evaluation of the use of braces to prevent injury to the knee in collegiate football players.

Data were collected in 1984 from seventy-one schools that were members of Division I of the National College Athletic Association and in 1985 from sixty-one of these schools to assess whether the use of so-called preventive braces for the knee was associated with a decrease in either the severity or the incidence (or both) of injuries to the knee in collegiate football players. Over-all, players who wore braces on the knees had significantly more injuries to the knee than players who did not. The severity of the injuries was no different in the two groups. Based on these findings, we cannot recommend the use of these braces in an attempt to prevent injury to collegiate football players.

Adult↗
PubMed1986

Effect of age at loss of dietary control on intellectual performance and behavior of children with phenylketonuria.

We determined the effect on intellectual performance and behavior of the age at which dietary control was lost in 119 10-year-old children with phenylketonuria (PKU) who had started on a diet low in phenylalanine before the age of 65 days. The children's diets were considered to be out of control when their blood phenylalanine concentration persistently exceeded 15 mg per deciliter. The age at which control was lost was the best, and frequently the only, predictor of the child's IQ at the age of 8 or 10 years and of the deficit in the child's IQ as compared with those of his or her unaffected siblings or parents. The age at which control was lost was also the best predictor of the deficit in scores on the Wide Range Achievement Test of children with PKU at the age of eight, as compared with their unaffected siblings, and of behavior problems (Louisville Behavior Checklist). Variables that were not significant included the maximal phenylalanine concentration before dietary therapy, the age at which treatment was started, and the family's coping abilities. The greatest deficiencies in all of these outcomes were observed among children who were out of dietary control before the age of six years. The highest correlation between the IQs of the children with PKU and their respective parents was observed among the children still on the diet at the age of eight years; the lowest, among those who had poor dietary control before the age of six. These findings suggest that phenylalanine restriction should continue after the age of eight years in children with PKU.

Adolescent↗
PubMed1986

Effect of cigarette smoking on survival of patients with angiographically documented coronary artery disease. Report from the CASS registry.

Through a multicenter registry of patients in the Coronary Artery Surgery Study, we prospectively evaluated morbidity and mortality in 4,165 smokers with angiographically proved coronary artery disease, 2,675 of whom continued to smoke and 1,490 of whom quit. At five years, mortality (adjusted by Cox analysis for baseline differences) was 22% for those who continued smoking and 15% for quitters. The relative risk (also from the Cox analysis) for mortality in continuers vs quitters was 1.55 (95% confidence interval, 1.29 to 1.85). The adverse effect of smoking mainly took the form of higher frequencies of myocardial infarction--associated death and sudden death: the frequencies of these events during follow-up in continuers vs quitters were 7.9% vs 4.4% for myocardial infarction--associated death and 2.8% vs 1.5% for sudden death. This study supports the recommendation that patients with coronary artery disease should stop smoking.

Coronary Disease↗
PubMed1986

Seven year survival of patients with normal or near normal coronary arteriograms: a CASS registry study.

The effect on 7 year survival of having a normal or near normal coronary arteriogram was examined using data from the CASS registry of 21,487 consecutive coronary arteriograms taken in 15 clinical sites. Of these, 4,051 arteriograms were normal or near normal, and the patients had normal left ventricular function as judged by absence of a history of congestive heart failure, no reported segmental wall motion abnormality and an ejection fraction of at least 50%; 3,136 arteriograms were entirely normal and the remaining 915 revealed mild disease with less than 50% stenosis in one or more segments. The 7 year survival rate was 96% for the patients with a normal arteriogram and 92% for those whose study revealed mild disease (p less than 0.0001). Nine risk variables recorded at entry were analyzed for predictive value for survival: age, sex, height, weight, history of smoking, presence of absence of mild disease, electrocardiographic response to exercise, family history of coronary heart disease and a history of hypertension. Of these, age, smoking history, presence or absence of disease and a history of hypertension had predictive value.

Adult↗
PubMed1986

Natural history of Giardia infection of infants and children in rural Guatemala and its impact on physical growth.

Longitudinal data on Giardia excretion, diarrheal disease, and physical growth during the first 3 yr of life collected more than 20 yr ago in 45 Guatemalan children were analyzed. This report describes the natural history of this infection and estimates its effects on growth. All children had at least one Giardia infection, prevalence and incidence rates reaching 20.2% and 5.3%, respectively by the end of the third year. The mean number of Giardia infections per child increased from 0.7 in the first to 3.6 in the third year. More than 40% of these infections lasted 2-6 wk or more and were commonly associated with diarrhea. Weight velocity was significantly lower in the second year of life in Giardia-infected than in Giardia-negative children (p = 0.03). The duration of Giardia episodes and their association with diarrhea appeared to be the most important factors associated with growth disturbance. Although simultaneous infection with other enteropathogens occurred in many children, our findings suggest that Giardia infection may have independent deleterious effects on children's growth.

Body Height↗
PubMed1985

Comparison of coronary artery bypass surgery and medical therapy in patients 65 years of age or older. A nonrandomized study from the Coronary Artery Surgery Study (CASS) registry.

We compared the results of coronary artery bypass surgery with those of medical therapy alone in 1491 nonrandomized patients 65 years of age or older. Cumulative survival at six years (adjusted for major differences in important base-line characteristics) was 79 per cent in the surgical group and 64 per cent in the medical group (P less than 0.0001). At five years, chest pain was absent in 62 per cent of the surgical group and 29 per cent of the medical group (P less than 0.0001). Analysis by the Cox proportional-hazards model suggested an independent beneficial effect of surgery on survival (P less than 0.0001). Patients were divided into risk quartiles on the basis of preoperative predictors of survival identified by the Cox model. Surgical benefit was greatest in "high-risk" patients (those in the two quartiles containing patients with the poorest prognosis). Among 234 "low-risk" patients with mild angina, relatively good ventricular function, and no left main coronary artery disease, there was no survival difference between those treated medically and those treated surgically. We conclude that in specific higher-risk subsets of non-randomized patients 65 years of age or older, coronary bypass surgery appeared to improve survival and symptoms in comparison with medical therapy alone. These conclusions must be tempered by consideration of the limitations of nonrandomized studies, particularly since patients in the two treatment groups differed substantially with regard to important base-line characteristics.

Aged↗
PubMed1985

Determinants of operative mortality and long-term survival in patients with unstable angina. The CASS experience.

To identify the factors that determine operative mortality and long-term survival, we analyzed the data from 3,311 patients who underwent surgical therapy for unstable angina according to clinical presentation. Overall operative mortality was 3.9% and no differences in operative mortality were found between patients with coronary insufficiency, new-onset angina, rest angina, or changing patterns of angina. Logistic regression analysis indicated that age, left ventricular score, and presence of a left main stenosis in a left dominant circulation were related to operative mortality. The 7 year cumulative survival rate was 79%. Features predictive of long-term outcome by Cox analysis included left ventricular score, congestive heart failure score, other illness, extent of coronary disease, and cardiomegaly. Operative mortality of those patients who underwent coronary bypass during their initial hospitalization with unstable angina was similar to that of patients who were discharged and readmitted for operation at a later date. Thus, patients with unstable angina demonstrate a relatively low operative mortality, which is unrelated to the clinical presentation. Long-term survival is primarily determined by clinical and angiographic markers of left ventricular dysfunction, associated illness, and the extent of coronary disease.

Angina Pectoris↗