Biomedical subjects

L E Chambless

Publications and source records attributed to L E Chambless.

At least 109 records · Page 6Linked to original sources

PubMed1987

Cigarette smoking, alcohol consumption, and breast cancer risk.

The effects of cigarette smoking and alcohol consumption on breast cancer risk were investigated in 276 primary, histologically confirmed breast cancer patients and 1,519 community-based comparison subjects identified in 1977 and 1978 in North Carolina. Data on both behaviors and other pertinent personal and medical characteristics were obtained by interview. Analytic methods included stratification and logistic regression. Among current cigarette smokers of 1-20 cigarettes per day and over 20 per day, the odds ratios (ORs) adjusted for age, race, alcohol consumption, estrogen use, and oral contraceptive use for breast cancer were 0.75 [95% confidence interval (CI) 0.52-1.09] and 0.57 (95% CI 0.30-1.08), respectively. A decrease in risk was not seen in former smokers. With respect to alcohol consumption, the adjusted OR for those having one drink or more per week compared to those having less than one was 1.45 (95% CI 0.99-2.12). If the comparison was ever versus never drinkers, the adjusted OR was 1.47 (95% CI 1.10-1.97); for current drinkers versus nondrinkers, the adjusted OR was 1.89 (95% CI 1.40-2.56). The ORs were adjusted for age, race, cigarette smoking, estrogen use, an oral contraceptive use. These data supports those reports showing an inverse association of cigarette smoking and a positive association of alcohol consumption with breast cancer risk.

Adult↗

PubMed1986

A screening survey of dyslipoproteinemias associated with prescription drug use. The Lipid Research Clinics Program Prevalence Study.

In 10 North American study populations, we surveyed alterations in blood cholesterol, triglyceride, and high-density lipoprotein cholesterol levels associated with the use of 20 categories of prescription medications. In addition, odds ratios for use of these medication categories were determined for five of the more common dyslipoproteinemias found in these populations. Increased lipid levels were found in association with use of several categories of cardiovascular drugs as well as allopurinol and warfarin. Decreased lipid levels were found in association with anti-infective agents and thyroid hormone. Few significant lipid level alterations were found with the use of antihistamines, barbiturates, analgesics, and the phenothiazines. The associations described here must be interpreted cautiously because of limitations in the study design, particularly the confounding effects of the conditions under drug treatment. However, several drug-lipid effects are suggested that may alter lipid levels and that require experimental confirmation. These findings have implications for both clinical management of individuals with dyslipoproteinemias and in the determinants and modification of population lipid levels.

Adult↗

PubMed1986

The association of dyslipoproteinemia with symptoms and signs of peripheral arterial disease. The Lipid Research Clinics Program Prevalence Study.

Intermittent claudication, leg pain during a graded exercise test (GXT), and resting systolic pressures in the upper and lower extremities were recorded as indicators of peripheral arterial disease at visit 2 of the Lipid Research Clinics (LRC) Prevalence Study. Systolic pressures of the upper and lower extremities were measured in a subsample of participants. We compared lipid levels of persons with and without claudication and with or without GXT-induced leg pain. We also compared lipid levels between groups with high and low arm:ankle systolic blood pressure ratios. Twenty-one (1.0%) men, 10 (1.0%) female nonusers and six (1.0%) female users of gonadal hormones had intermittent claudication determined by standardized questionnaire. Men with claudication had lower high-density lipoprotein (HDL)-cholesterol (35.6 vs 46.4 mg/dl), and their mean triglyceride level and cigarette consumption were higher and regular exercise less frequent. Men with type IIb dyslipoproteinemia were more likely to report claudication. One hundred sixty-nine (4.0%) men, 101 (3.8%) female nonusers, and 47 (4.1%) female users of hormones stopped the GXT because of leg pain. Mean HDL-cholesterol levels were lower for those with GXT-induced leg pain in all three sex-hormone usage groups (42.0 vs 46.9, p less than .001; 53.9 vs 59.4, p less than .001; 65.3 vs 67.2, p = NS) and mean low-density lipoprotein cholesterol levels were higher in those with leg pain on GXT in two of three groups (146.4 vs 146.2, p = NS; 155.7 vs 144.6, p less than .01; 144.4 vs 133.5, p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

The association of dyslipoproteinemia with corneal arcus and xanthelasma. The Lipid Research Clinics Program Prevalence Study.

The prevalence rates of xanthelasma and corneal arcus were computed for normolipidemic and dyslipoproteinemic participants in the Lipid Research Clinics population surveys. The prevalence of both xanthelasma and corneal arcus increased with age, was highest in persons with type II phenotype, and usually low in those with type IV phenotype. The relative effects of age and use of gonadal hormones were different in the two lesions. Both xanthelasma and corneal arcus were associated with increased levels of plasma cholesterol and low-density lipoprotein cholesterol (LDL-C), especially in young males. In general, persons with either lesion had increased odds of having type IIa dyslipoproteinemia but decreased odds of having type IV. Xanthelasma and corneal arcus were highly associated with each other, especially in young people. There was no consistent univariate association of xanthelasma and corneal arcus with smoking, alcohol consumption, blood pressure, obesity, sedentary lifestyle, family history of ischemic heart disease, or glucose and uric acid plasma concentrations. Adjusted odds ratios for ischemic heart disease in participants with xanthelasma and corneal arcus were generally increased, except in older female nonusers of gonadal hormones, in whom they were significantly decreased. Neither xanthelasma nor corneal arcus showed a consistent association with manifestations of peripheral arterial disease. Thus the clinical findings of xanthelasma or corneal arcus, especially in young people, seem to identify persons with plasma lipoprotein abnormalities.

Adult↗

PubMed1986

Patterns of dyslipoproteinemia in selected North American populations. The Lipid Research Clinics Program Prevalence Study.

This article describes the assignment of dyslipoproteinemia (DLP) in several free-living North American populations and presents mean lipid and lipoprotein levels for each type. Dyslipoproteinemic phenotypes were assigned by a modified version of the National Institutes of Health (Fredrickson) phenotyping system. Criteria for assigning phenotypes included age- and sex-specific 5th and 95th percentiles for low-density lipoprotein and high-density lipoprotein cholesterol and total triglyceride, as well as other qualitative and quantitative criteria. Phenotypes IIb, III, I, and V were uncommon, confirming clinical impressions of their frequency. Lipid and lipoprotein levels in specific phenotypes were generally as expected. In the type III phenotype, however, mean cholesterol and triglyceride levels were surprisingly low. Gonadal hormone use, in the form of both oral contraceptives and postmenopausal estrogens, was reported in approximately 30% of women in these populations and was associated with dramatic differences in the frequency of DLP when compared with women not taking hormones. In general, these differences reflected the previously described effects of estrogen and progestins on lipoprotein levels. These data gathered in free-living populations: confirm clinical impressions of the rarity of some phenotypes, focus attention on those phenotypes in which diminished rather than elevated lipoproteins are found, and provide further evidence of the effect of hormones on lipid and lipoprotein levels.

Adolescent↗

PubMed1986

Detection of dyslipoproteinemia with the use of plasma total cholesterol and triglyceride as screening tests. The Lipid Research Clinics Program Prevalence Study.

The efficiency of screening for dyslipoproteinemias associated with hyperlipoproteinemia or with hypolipoproteinemia was examined in 8449 white examinees from the Lipid Research Clinics Prevalence Study. A two-stage lipid screening approach was used. A positive screening test for hyperlipidemia was defined as an elevated level of plasma total cholesterol or triglyceride at both visit 1 and visit 2. A positive screening test for hypolipidemia was defined as a reduced plasma total cholesterol level at both visits. The syndromes of dyslipoproteinemia were defined according to the lipoprotein pattern present at visit 2. When hyperlipidemia was used as a screening tool, generally only about one-half or less of the cases of hyperlipoproteinemia were detected (high proportion of false-negative results). Of all the hyperlipidemic participants, more than 80% had hyperlipoproteinemias (type I, IIa, IIb, III, IV, or V), and such lipid screening therefore provided a lower proportion of false-positive than false-negative results. Most of the participants (greater than 98%) without hyperlipoproteinemia were correctly identified (true negatives). The efficiency of screening for hypolipoproteinemia was in general poorer than that found for hyperlipoproteinemia. Our results were found to be related, in part, to the marked regression to the mean of plasma cholesterol and triglycerides at the extremes of the distributions and to the wide variety of dyslipoproteinemias that can be present within a given range of plasma cholesterol or triglyceride values. The results emphasize the importance of measuring plasma lipoproteins in the patient who is being evaluated for dyslipoproteinemia.

Adolescent↗

PubMed1986

Populations and methods for assessing dyslipoproteinemia and its correlates. The Lipid Research Clinics Program Prevalence Study.

This article presents the basic methods and populations of the Lipid Research Clinics (LRC) Program Prevalence Study. The purpose is to provide a frame of reference for the other articles in this monograph; hence, the populations and major data collected are described briefly, as are procedures for enhancement of data quality and approaches to statistical analysis. More detailed descriptions for some procedures are included in the pertinent articles. The two sequential screening examinations of the Prevalence Study provided 60,502 participants from centers in the United States and Canada for the first phase and 13,852 for the second. The monograph is based on data from 11,657 white and 644 black participants aged 6 years or older screened at both visits.

Adolescent↗

PubMed1986

Frequency and clustering of nonlipid coronary risk factors in dyslipoproteinemia. The Lipid Research Clinics Program Prevalence Study.

In a defined population of 4349 men and 3398 women, we evaluated the frequency and clustering of five nonlipid coronary heart disease risk factors--obesity, hypertension, sedentary lifestyle, cigarette smoking, and alcohol consumption--in nine categorical lipoprotein phenotypes--normal, types I or V, IIA, IIB, III, IV, hypoHDL (high-density lipoprotein), hypoLDL (low-density lipoprotein), and hyperHDL. This analysis indicated that compared with the normal phenotype, nonlipid coronary risk factors tend to be more frequent and thus cluster in individuals with "high risk" phenotypes, and occur somewhat less frequently in those with "low risk" phenotypes. Thus, identification of a high-risk phenotype suggests the presence of nonlipid risk factors as well, and the clinician should be alert to this possibility. A multivariable analysis of the independent associations of each of the risk factors with the lipid and lipoprotein components that define the phenotypes suggested that several behavioral risk factors may directly affect lipid and lipoprotein levels. This observation raises the possibility that certain intervention strategies, such as weight loss, smoking cessation, and regular exercise, may favorably influence dyslipoproteinemia.

Adult↗

PubMed1986

Progeny's lipid and lipoprotein levels by parental mortality. The Lipid Research Clinics Program Prevalence Study.

Using data from Lipid Research Clinics study participants at visit 2 (3972 and 2346 adult men and women), we examined the hypothesis that parental mortality from cardiovascular disease (CVD) or cancer before age 60 predicts their adult progeny's lipid and lipoprotein levels. Weighted regression analysis was used to control for the potential effect of progeny's other CVD risk factors (age, systolic blood pressure, Quetelet index, cigarette smoking, and alcohol consumption), and to assess for the effect of progeny's parental cause-specific mortality status on progeny's lipids and lipoproteins. Nearly all of the statistically significant parent-progeny predictions were for sons. Paternal death from CVD before age 60 years was associated with significantly higher plasma total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels in sons and (at marginal significance) in daughters, when compared with those in reference progeny with paternal survival over age 60 or over age 75. Maternal death from CVD before 60 was associated with lower levels of high-density lipoprotein cholesterol (HDL-C) in sons. Paternal and maternal death from cancer before age 60 years were associated with higher triglyceride levels in adult sons than in sons whose parents had lived beyond ages 60 and 75. Paternal all-cause mortality before age 60 was associated with higher cholesterol and triglycerides in sons; maternal all-cause mortality before age 60 was associated with depression of HDL-C in sons. Familial aggregation of lipids and lipoproteins may account, in part, for familial aggregation of CVD. Knowledge of family history facilitates identification of progeny at higher risk for CVD by virtue of elevated cholesterol or LDL-C, or reduced HDL-C.

Adult↗

PubMed1986

Alterations in clinical chemistry levels associated with the dyslipoproteinemias. The Lipid Research Clinics Program Prevalence Study.

Mean blood levels of eight components of clinical chemistry and the proportion of participants with abnormal chemistry values were calculated for persons with six dyslipoproteinemias (DLPs) and compared with findings from normolipidemic participants in 10 defined North American Lipid Research Clinics Program study populations. Most of the significant differences in mean chemistry levels were in persons with type IIB and IV DLP, and were characterized by higher mean levels of serum alkaline phosphatase, glucose, SGOT, and uric acid, and by lower mean levels of total bilirubin and thyroxine. Similarly, persons with type IIB and IV DLP were more likely to have significantly increased percentages of abnormal clinical chemistry values than were normolipidemics, but for a given chemistry this was rarely over 10% to 15% higher. With the exception of some participants with types IIB and IV DLP, the DLPs detected in these study populations were not associated with a substantial prevalence of abnormal clinical chemistry values and, by inference, were not frequently associated with the diseases or metabolic abnormalities for which these chemical abnormalities are indicators.

Adult↗

PubMed1986

Dyslipoproteinemias and manifestations of coronary heart disease. The Lipid Research Clinics Program Prevalence Study.

The Lipid Research Clinics Prevalence Study population underwent a noninvasive evaluation to assess the odds of coronary heart disease (CHD) among individuals with various types of dyslipoproteinemia (DLP) relative to the odds for individuals free of DLP in a nonselected population. The noninvasive evaluation included the Rose questionnaire for angina, a resting electrocardiogram, and a graded treadmill exercise test. The presence of manifestations of CHD was assessed by a combination of these findings. Multiple linear regression and multiple logistic regression analyses were used to evaluate associations between CHD and DLP, with adjustments for the following covariates: age, body mass, systolic blood pressure, alcohol consumption, and cigarette use. There were no consistent associations in women or in men 30 to 49 years old. In men 50 to 69 years old, the mean high-density lipoprotein cholesterol (HDL-C) values and HDL-C/cholesterol ratio were significantly lower in the definite CHD and angina categories, compared with the negative (no evidence of CHD) group. Higher odds ratios for CHD were present in those classified as having type IIa, type IV, and hypoHDL DLPs, relative to those classified as normal by the phenotyping algorithm. These associations were consistent across the several categories of CHD manifestations, but did not reach statistical significance after adjustment for multiple testing. A statistically significant lower odds ratio for CHD was observed in men 50 to 69 classified as having hyperHDL when compared with those without DLPs. The associations between CHD and the various forms of DLP were consistent with those observed between CHD and the plasma lipid and lipoprotein-cholesterol concentrations. The Lipid Research Clinics Prevalence Study confirmed the relationship between elevated low-density lipoprotein cholesterol, decreased HDL-C, and noninvasively determined CHD in a free-living asymptomatic population of older men.

Adult↗

PubMed1985

A comparison of direct adjustment and regression adjustment of epidemiologic measures.

Although regression adjustment can provide a useful alternative to direct adjustment, especially when data are sparse, many researchers are unaware that adjusted summary measures can be easily derived from regression coefficients. In a non-technical discussion with examples, the direct adjustment procedure is compared with three methods of regression adjustment based on analysis of covariance models: the conditional prediction method, the stratified prediction method, and the marginal prediction method. Both the stratified prediction and direct adjustment methods yield summary measures that are weighted averages of stratum-specific measures, while adjusted measures from the conditional prediction method are similar to stratum-specific estimates. In contrast to the other adjustment procedures, which can use internal or external weights, the marginal prediction method always gives an internally adjusted measure. Under certain conditions, the three regression adjustment procedures produce identical results. Major advantages of direct adjustment include computational simplicity and relatively few statistical assumptions. Regression adjustment, however, is more convenient for statistical tests for interactions and group differences, and often precludes the need to categorize continuous variables, so that problems with empty strata are avoided.

Age Factors↗

PubMed1985

Menopausal change in serum cholesterol. Black/white differences in Evans County, Georgia.

The relationship between menopausal status and total serum cholesterol was examined cross-sectionally in a population of 40- to 54-year-old black and white women of Evans County, Georgia. The relationship differed in blacks and whites as assessed by a significant interaction term in linear regression. Controlling for age, Quetelet index, and smoking status, white postmenopausal women showed an estimated increase in total serum cholesterol of 25 mg/dl (p less than 0.001) compared with premenopausal whites, whereas black postmenopausal women showed no significant increase in total serum cholesterol compared with premenopausal blacks. The authors were unable to attribute the lack of menopausal effect in blacks to selection or measurement bias, nor did confounding or effect modification by obesity or social status negate their findings. Of six other populations in which menopausal influence on total serum cholesterol has been examined, only Pima Indians failed to show a significant increase.

Adult↗

PubMed1984

Hormonal and personal effects on estrogen receptors in breast cancer.

Since high estrogen receptor protein in breast cancer tissue has a favorable effect on patient prognosis, factors influencing estrogen receptor levels are the focus of this research. From April 1977 to December 1978, 246 histologically confirmed primary breast cancer patients from three North Carolina hospitals were interviewed and provided with photographic displays of hormonal products. Their tumor tissue was analyzed for estrogen receptor protein by the sucrose density gradient assay. Data were analyzed by multiple regression and logistic regression techniques. No statistically significant relationship was found between gonadal hormone usage and estrogen receptor levels, although recent users of either oral contraceptives or replacement estrogens had lower receptor levels. Users of progestogen-predominant and -intermediate types of oral contraceptives also had lower estrogen receptor protein. An effect of menopausal status, independent of age, was not evident. Statistically significant associations involved age and race among postmenopausal patients. With black breast cancer patients aged less than 70 years as the reference group, the relative odds of having high estrogen receptor protein (greater than 10 fmol/mg of cytosol protein) were 2.4 times greater among whites aged less than 70, 1.6 times greater in blacks aged greater than or equal to 70, and 12.8 times greater in whites greater than or equal to 70 years. These differences in estrogen receptor protein may contribute to the black-white differential in breast cancer survival.

Adult↗

PubMed1982

Breast cancer and estrogen replacement therapy.

Concern over the possible effect of estrogen replacement therapy on the subsequent development of breast cancer prompted us to compare 199 postmenopausal breast cancer patients with 451 hospital control subjects and 852 community control subjects on their prior use of estrogens. Estrogen use did not increase the breast cancer risk for women with a surgical menopause. Among women with a natural menopause, estrogens administered by all routes were associated with breast cancer risks of 1.7 of 1.8. There was no coherent pattern of changing risks with varying durations of use, different daily dosages, years since first use of estrogen, or years since most recent use. When women who usually received estrogen by injection were excluded, the risk estimates for oral estrogens were 1.3 (case subjects compared to community control subjects) and 1.2 (case subjects compared to hospital control subjects). These increases were not statistically significant. Use of injectable estrogens produced a fourfold increase in breast cancer risk among naturally postmenopausal women.

Administration, Oral↗

PubMed1982

Statistical methods in the study of toxic shock syndrome.

Analysis of statistical methods used in matched case-control studies of toxic shock syndrome shows that matching has implications for validity and precision of the studies and for the choice of analysis techniques. The studies considered accounted for the matching in the analysis, either by the Mantel-Haenszel or Miettinen-Pike-Morrow approach to 1-to-M matched designs, or by the use of conditional maximum likelihood fitting of logistic regression models. Methods of dealing with confounding and effect modification in the (matched) logistic regression model are presented in the context of studies of toxic shock syndrome. The varied statistical techniques used in these studies were generally appropriate to the matched design except that nonmatching variables were not thoroughly considered as effect modifiers or confounders.

Carboxymethylcellulose Sodium↗

PubMedDate not supplied

A community-based study of explanatory factors for the excess risk for early renal function decline in blacks vs whites with diabetes: the Atherosclerosis Risk in Communities study.

CONTEXT: The explanation for the excess risk for diabetic renal disease in blacks is uncertain. OBJECTIVES: To compare the incidence of early renal function decline in black and white adults with diabetes and to examine possible explanatory factors for racial differences. DESIGN: Prospective cohort study. SETTING: Four US communities participating in the Atherosclerosis Risk in Communities study. PARTICIPANTS: Community-based sample of 1434 diabetic adults aged 45 to 64 years. MEASUREMENTS: Detailed baseline assessment using structured interview, results of physical examination, and laboratory measurements. MAIN OUTCOME: Development of early renal function decline defined by an increase in serum creatinine of at least 35.4 micromol/L (0.4 mg/dL) during 3 years of follow-up. RESULTS: During 3 years of follow-up, early renal function decline developed in 45 blacks (28.4 per 1000 person-years [PY]) and 25 whites (9.6 per 1000 PY). After adjustment for age, sex, and baseline serum creatinine level, early renal function decline was more than 3 times as likely to develop in blacks than whites (odds ratio, 3.15; 95% confidence interval, 1.86-5.33). Additional adjustment for education, household income, health insurance, fasting glucose level, mean systolic blood pressure, smoking history, and physical activity level reduced the relative odds in blacks to 1.38 (95% confidence interval, 0.71-2.69), corresponding to a 82% reduction in excess risk. CONCLUSIONS: These data suggest that early renal function decline is 3 times more likely to develop in blacks than whites and that potentially modifiable factors, including lower socioeconomic status, suboptimal health behaviors, and suboptimal control of glucose level and blood pressure, account for more than 80% of this disparity.

Black People↗

PubMedDate not supplied

Correlation of factor VIIa values with factor VII gene polymorphism, fasting and postprandial triglyceride levels, and subclinical carotid atherosclerosis.

BACKGROUND: Factor VII plays a pivotal role in coagulation. Factor VIIc levels were reported to be a risk factor for fatal coronary heart disease (CHD). Factor VIIc and VIIag levels were noted to be positively associated with plasma triglyceride (TG) levels and influenced by a VII gene polymorphism. The purpose of this study is to determine whether these associations are related to activated factor VII (factor VIIa). METHODS AND RESULTS: Fasting and 3.5-hour postprandial samples from 216 cases with subclinical atherosclerosis and 341 matched controls selected from the ARIC cohort were assayed for levels of factors VIIa, VIIc, and VIIag and TG, and factor VII codon 353 gene polymorphism. The level of factor VIIa was higher in Arg/Arg than in Arg/Gln+Gln/Gln genotypes, and the difference was in accord with that of factors VIIag and VIIc. However, the factor VIIa difference was statistically insignificant. Factor VIIa values were not correlated with fasting or 3.5-hour postprandial TG levels, nor were they associated with subclinical atherosclerosis. CONCLUSIONS: Factor VIIa levels, like factor VIIag and VIIc levels, are influenced by factor VII gene codon 353 polymorphism. However, unlike factor VIIag or VIIc, factor VIIa is not influenced by TG levels; none of these is associated with subclinical atherosclerosis.

Arteriosclerosis↗