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T Byers

Publications and source records attributed to T Byers.

At least 55 records · Page 3Linked to original sources
PubMed1996

Reliability of alcohol intake as recalled from 10 years in the past.

The authors assessed the reliability of alcohol intake as recalled from 10 years in the past in a cohort of 2,907 US adults. Participants reported their drinking habits in the First National Health and Nutrition Examination Survey interview during 1971-1975. During a follow-up interview in 1982-1984, they were asked to recall their drinking habits 10 years earlier and to report their current habits. In general, the correlation for recalled alcohol intake versus reported intake at baseline was good (r = 0.7). For all subgroups stratified by race, sex, education, smoking status, and disease status, the age-adjusted correlations for recalled alcohol intake versus baseline intake were equal to or higher than those for current alcohol intake versus baseline intake. The reliability of recall of alcohol intake in the past differs among subgroups with different age and education levels. Recalled alcohol intake was also highly correlated with current alcohol intake; in particular, current heavier drinkers tended to underestimate their previous amount of drinking, an effect that was independent of other factors. These data suggest that although recalled alcohol intake is a better predictor of past intake than are reports of current intake, current drinking habits may be an important influencing factor in the estimation of alcohol intake as recalled from the distant past.

Adult↗
PubMed1996

Correlates of leukocyte counts in men.

Because of previously reported associations between a high leukocyte count and risk of ischemic heart disease (IHD), we examined the relation of leukocyte counts to various characteristics among 3591 white and 506 black 31- to 45-year-old men. The mean leukocyte count was approximately 1000 cells/microL higher among whites than among blacks, and approximately 1900 cells/microL higher among current smokers than among nonsmokers. The leukocyte count was also higher among men who had recently stopped smoking and among men who reported their general health as poor or fair. Independent of these relations, the leukocyte count was associated positively with the platelet count (r = 0.29), triglyceride level (r = 0.21), heart rate (r = 0.15), and use of corticosteroids and beta-blockers; and inversely with alcohol consumption and prothrombin time (r = -0.10). The examined characteristics could together account for 37% of the variability in leukocyte counts. These relatively strong associations indicate that it may be difficult to disentangle the relation of the leukocyte count to IHD from that of other risk factors.

Adult↗
PubMed1996

A search for recall bias in a case-control study of diet and breast cancer.

BACKGROUND: In retrospective studies of dietary habits and breast cancer risk, recall bias is a concern since diet has been publicized as a cause of breast cancer. METHODS: In a case-control study of diet and breast cancer risk nested within a cohort of women screened with mammography, we contrasted answers to a retrospective dietary interview with answers to a dietary questionnaire which was filled out before any diagnostic procedures for breast cancer were undertaken. The source population was all women aged 40-74 in two counties in Sweden invited to mammographic screening and asked to fill out a questionnaire before the screening. Cases and controls were subsequently defined -- matched on age, county of residence, and time of mammography -- and approached for an interview. RESULTS: In all, 265 cases and 431 controls participated in the study. Means of frequencies differed between the agreement in the questionnaire's and the interview's classifications of study subjects into quartiles of monthly intake varied between 31 percent and 57 percent. Kappa statistics in all food groups were below 0.41. In a regression analysis, case subjects with low responses on the questionnaire about intake of meat, snacks, and coffee and tea gave higher responses on interview than did controls who had low questionnaire responses for these food groups. The reverse was also true: cases' responses that were high on the questionnaire were lower on interview for these food groups than were controls' responses. CONCLUSIONS: We found few signs of recall bias, and the few indications of a differential misclassification that we found were not in food groups that have been publicly discussed as causes of breast cancer.

Adult↗
PubMed1996

The association between fruit and vegetable intake and chronic disease risk factors.

Understanding the associations between fruit and vegetable intake and other health behaviors is important for properly interpreting the rapidly growing number of studies that link low intakes of fruits and vegetables to the risk of cancer and cardiovascular disease. To examine the association between fruit and vegetable intake and behavioral risk factors for chronic diseases, we analyzed data from a population-based behavioral risk factor survey. Data were collected in 1990 from 21,892 adults in 16 states by a random-digit-dial telephone survey. Respondents answered questions about behaviors related to chronic disease risk, including their frequency of intake of fruits and vegetables, using a six-item questionnaire. Consumption of fruits and vegetables was lowest among those who also reported that they were sedentary, heavy smokers, heavy drinkers, or had never had their blood cholesterol checked. Because fruit and vegetable intake covaries with several other chronic disease risk factors, it is important to account for possible confounding between fruit and vegetable intake and other behaviors in etiologic studies of the risk of cancer and cardiovascular disease.

Adolescent↗
PubMed1996

Does diabetes mellitus increase the requirement for vitamin C?

This paper reviews the scientific evidence regarding the vitamin C status of people with diabetes mellitus and whether they might have increased dietary vitamin C requirements. English language articles published from 1935 to the present that either compare ascorbic acid concentrations of persons with and without diabetes mellitus or assess the impact of vitamin C supplementation on various health outcomes among persons with diabetes mellitus were examined. Most studies have found people with diabetes mellitus to have at least 30% lower circulating ascorbic acid concentrations than people without diabetes mellitus. Vitamin C supplementation had little impact on blood glucose concentrations, but was found to lower cellular sorbitol concentrations and to reduce capillary fragility. Much of the past research in this area has been methodologically weak. To further understand the relation of ascorbic acid and diabetes mellitus, randomized clinical trials of ascorbic acid supplementation should be a high priority for research.

Ascorbic Acid↗
PubMed1996

Trends in overweight among US adults from 1987 to 1993: a multistate telephone survey.

OBJECTIVES: Using data from the Behavioral Risk Factor Surveillance System, this study describes trends in the prevalence of overweight between 1987 and 1993. METHODS: Data were examined from 33 states participating in an ongoing telephone survey of health behaviors of adults (n = 387,704). Self-reported weights and heights were used to calculate sex-specific prevalence estimates of overweight for each year from 1987 to 1993. Time trends were evaluated with the use of linear regression. RESULTS: Between 1987 and 1993, the age-adjusted prevalence of overweight increased by 0.9% per year for both sexes (from 21.9% to 26.7% among men and from 20.6% to 25.4% among women). The increasing linear trend was observed in all subgroups of the population but was most notable for Black men (1.5% per year) and men living in the Northeast (1.4% per year). Secular changes in smoking and leisure-time physical activity did not entirely account for the increase in overweight. CONCLUSIONS: The prevalence of overweight among American adults increased by 5% between 1987 and 1993. Efforts are needed to explore the causes of this adverse trend and to find effective strategies to prevent obesity.

Adult↗
PubMed1996

Menstrual patterns and breast cancer mortality in a large U.S. cohort.

We examined the relation between menstrual irregularity and breast cancer mortality in the American Cancer Society Cancer Prevention Study I. In 1959, 428,653 women age 30 years and older completed a questionnaire on possible cancer risk factors, including their recollection of their menstrual pattern at age 20 years. We used proportional hazards analysis to estimate rate ratios, based on 2,226 breast cancer deaths over 13 years of follow-up. Women who reported having irregular menstruation at age 20 years were at reduced risk for breast cancer mortality (rate ratio = 0.84; 95% confidence interval = 0.74-0.96). The relation was neither confounded nor modified by other breast cancer risk factors.

Adult↗
PubMed1995

Relation of weight variability and intentionality of weight loss to disease history and health-related variables in a population-based sample of women aged 55-69 years.

The authors examined the relation of recalled weight variability and history of intentional and unintentional weight loss with disease history in 41,837 older women. Lifetime history of disease, current medication use, health-related behaviors, body weight, and intentional and unintentional weight loss episodes of at least 20 lbs (9.1 kg) were assessed by means of two surveys, completed 6 years apart. Weight variability, as measured by the root mean square error around the linear regression line of weight on age at ages 18, 30, and 40 years, was positively related to disease history. Women who reported losing > or = 20 lbs (> or = 9.1 kg) unintentionally between the ages 18 and 39 years were more likely to report a history of disease than were women who had never lost > or = 20 lbs (> or = 9.1 kg) during this age period. Intentional weight loss episodes of > or = 20 lbs (> or = 9.1 kg) between ages 18 and 39 years were also associated with higher cumulative disease prevalence. These results suggest that both unintentional and, to a lesser degree, intentional weight loss may contribute to the observed positive relation between weight loss or variability and disease. Prospective studies are needed to confirm whether weight variability is a risk factor for disease only when unintentional, or whether intentional weight loss also increases risk.

Aged↗
PubMed1995

Relation of body fat distribution to ischemic heart disease. The National Health and Nutrition Examination Survey I (NHANES I) Epidemiologic Follow-up Study.

Although an excess of adipose tissue in the abdominal and truncal regions is associated with various metabolic alterations, relatively few cohort studies have examined its importance in the development of ischemic heart disease, and little information is available from black populations. The authors examined the relation of central obesity, as characterized by a thick subscapular skinfold relative to the triceps skinfold, to the incidence of ischemic heart disease among 9,822 persons in the Epidemiologic Follow-up Study of the National Health and Nutrition Examination Survey I; baseline data were collected in 1971-1975 and follow-up was through 1987. We found that, independently of relative weight, cigarette smoking, and other covariates, the hazard rate ratios for ischemic heart disease incidence contrasting the upper and lower quintiles of central obesity were 1.75 (95% confidence interval 1.3-2.3) among women and 1.65 (95% confidence interval 1.3-2.2) among men. Although central obesity was related similarly to disease among white and black men, the association among women differed between whites (rate ratio = 1.94) and blacks (rate ratio = 0.73); p = 0.002 for race x the central obesity product term. Additional research is needed to clarify the relation of various anthropometric measurements to ischemic heart disease, particularly among blacks, but the assessment of fat distribution may help identify high-risk persons for whom weight loss might be most beneficial.

Adipose Tissue↗
PubMed1995

Effects of question order on estimates of the prevalence of attempted weight loss.

Although numerous surveys have been conducted to estimate the prevalence of attempted weight loss, little information is available on the possible effects of question order on the prevalence estimates. The authors examined data collected from 231,852 respondents to surveys conducted in the District of Columbia and 20 states that participated in the Behavioral Risk Factor Surveillance System between 1985 and 1992. In surveys conducted from 1985 to 1988, respondents (n = 117,827) were first asked their body weight and then were asked if they were trying to lose weight; 48% of the women and 29% of the men reported that they were trying to lose weight. In 1989, 1991, and 1992 (no questions about weight control were asked in 1990), the order of the questions was reversed so that respondents (n = 114,025) were asked whether they were trying to lose weight before they were asked to report their weight; 41% of the women and 26% of the men reported that they were trying to lose weight. The authors conclude that survey respondents, especially women, may be more likely to report that they are trying to lose weight when questions about weight control practices immediately follow questions on current weight. This apparent effect of question order points to the need for caution in comparing prevalence estimates across surveys in which the questions are not asked in a similar order, even when the questions are worded identically.

Adult↗
PubMed1995

Prospective study of intentional weight loss and mortality in never-smoking overweight US white women aged 40-64 years.

Although 40% of US women indicate they are currently trying to lose weight, the association between intentional weight loss and longevity is unknown. The authors analyzed prospective data from 43,457 overweight, never-smoking US white women aged 40-64 years who in 1959-1960 completed a questionnaire that included questions on weight change direction, amount, time interval, and intentionality. Vital status was determined in 1972. Proportional hazards regression was used to estimate mortality rate ratios for women who intentionally lost weight compared with women who had no change in weight. Women who died within the first 3 years of follow-up were excluded. Analyses were stratified by preexisting illness and adjusted for age, beginning body mass index, alcohol intake, education, physical activity, and health conditions. In women with obesity-related health conditions (n = 15,069), intentional weight loss of any amount was associated with a 20% reduction in all-cause mortality, primarily due to a 40-50% reduction in mortality from obesity-related cancers; diabetes-associated mortality was also reduced by 30-40% in those who intentionally lost weight. In women with no preexisting illness (n = 28,388), intentional weight loss of > or = 20 lb (> or = 9.1 kg) that occurred within the previous year was associated with about a 25% reduction in all-cause, cardiovascular, and cancer mortality; however, loss of < 20 lb (< 9.1 kg) or loss that occurred over an interval of > or = 1 year was generally associated with small to modest increases in mortality. The association between intentional weight loss and longevity in middle-aged overweight women appears to depend on their health status. Intentional weight loss among women with obesity-related conditions is generally associated with decreased premature mortality, whereas among women with no preexisting illness, the association is equivocal.

Adult↗
PubMed1995

Relation of serum uric acid to mortality and ischemic heart disease. The NHANES I Epidemiologic Follow-up Study.

Although hyperuricemia is frequently found among persons with ischemic heart disease, its importance as a risk factor remains uncertain. The authors examined this relation among 5,421 persons in the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study; baseline data were collected in 1971-1975 and follow-up was through 1987. No associations were seen among men, but, among women, the serum uric acid level was predictive of mortality from all causes and from ischemic heart disease. These associations persisted even after excluding the first 10 years of follow-up and were independent of use of antihypertensive agents and diuretics, diastolic blood pressure, overweight, and other characteristics. A dose-response relation was evident for mortality from ischemic heart disease: each 1-mg/dl change in uric acid (about two thirds of the standard deviation) among women increased the rate by 1.48 (95% confidence interval 1.3-1.7). Furthermore, as compared with women who had a uric acid level < 4 mg/dl, those with a level > or = 7 mg/dl had a 4.8-fold (95% confidence interval 1.9-12) higher rate of ischemic heart disease mortality. In contrast, the uric acid level showed a weaker relation with disease incidence among women, with a rate ratio of 1.14 for each 1-mg/dl change. Although the biologic mechanism is unclear, further investigation into the possible role of uric acid in the development of ischemic heart disease is needed.

Adult↗
PubMed1995

Plasma lipid levels and psychologic characteristics in men.

Results of several studies suggest that either a reduction in the serum level of total cholesterol level or a persistently low cholesterol level may be associated with an increase in violent deaths. Although there are several possible explanations for these observations, it has been suggested that the cholesterol level could influence various behaviors. We therefore examined the cross-sectional relation of several psychologic characteristics, assessed by the Diagnostic Interview Schedule and the Minnesota Multiphasic Personality Inventory, to levels of total cholesterol, high-density lipoprotein cholesterol, and triglycerides among 3,490 men aged 31-45 years who were examined in 1985-1986. (All men had served in the US Army between 1965 and 1971). Compared with that of other men, the mean total cholesterol level was 5 mg/dl higher among 697 men diagnosed with generalized anxiety disorder (possibly because of increased catecholamine levels) and 7 mg/dl lower among 325 men with antisocial personality disorder (p < 0.01 for each association). These differences could not be attributed to education, relative weight, cigarette smoking, use of various medications, or other potential confounders. In contrast, cholesterol levels were not significantly associated with major depression or hostility; levels of high-density lipoprotein cholesterol and triglycerides were not related to any diagnosis. If the serum level of total cholesterol is found to be predictive of antisocial personality disorder in longitudinal analyses, this association may have implications for cholesterol-lowering recommendations.

Adult↗
PubMed1995

History of intentional and unintentional weight loss in a population-based sample of women aged 55 to 69 years.

Although both overweight and body weight fluctuation are related to chronic disease risk, little is known about the history of and reasons for body weight change in the general population. This paper reports the incidence of intentional and unintentional weight loss episodes during adulthood in a population-based sample of 26,261 women aged 55 to 69 years. Intentional weight loss episodes of each of four amounts (5-9, 10-19, 20-49, 50+ lbs.) and unintentional weight loss episodes of 20 or more lbs. were recalled for each of three age periods (18-39, 40-54, 55+ years). At least one intentional weight loss episode of 5 or more lbs. was reported by 69% of women, 46% reported at least one intentional weight loss episode of 10 or more lbs, and 25% reported at least one intentional weight loss episode 20 or more lbs. At least one unintentional weight loss episode of 20 or more lbs. was reported by 29% of the women. Reasons for weight losses of 20 or more lbs. were also recalled. Women who had intentionally lost 20 or more lbs. were more likely to report weight losses due to low-calorie diets, exercise and weight loss groups, while women who had unintentionally lost 20 or more lbs. were more likely to report weight losses due to depression or stress. These findings question the common assumption that weight losses in adult women are primarily intentional and emphasize the need to distinguish the reasons for weight loss in studies examining the relationship between body weight changes and health outcomes.

Aged↗
PubMed1995

Epidemiologic evidence for vitamin C and vitamin E in cancer prevention.

Antioxidant nutrients have been hypothesized to be protective against cancer. Vitamin C is a major circulating water-soluble antioxidant, and vitamin E is a major lipid-soluble antioxidant. Many case-control and cohort studies have related cancer risk to estimates of nutrient intake derived from food intake reports. Diets high in fruit and vegetables, and hence high in vitamin C, have been found to be associated with lower risk for cancers of the oral cavity, esophagus, stomach, colon, and lung. Diets high in added vegetable oils, and hence high in vitamin E, have been less consistently shown to be associated with cancer protection. This may be because vitamin E offers less protection against cancer or because the estimation of vitamin E intake is less accurate than is the estimation of vitamin C intake. In contrast with the findings from epidemiologic studies based on foods, observational studies of nutrients consumed in supplements and recent experimental trials provide little support for a strong protective role for vitamins C or E against cancer. If vitamins C or E are indeed protective against cancer, that protection may derive from their consumption in complex mixtures with other nutrients and with other bioactive compounds as found in the matrix provided by whole foods.

Ascorbic Acid↗
PubMed1995

A brief, telephone-administered food frequency questionnaire can be useful for surveillance of dietary fat intakes.

A 13-item questionnaire designed for quick telephone administration was evaluated for use in surveillance of fat intake in the United States. Study populations included 560 middle-aged and older adults from Beaver Dam, WI, 252 middle-aged and older women from Wisconsin, 73 young, low income Hispanic women from Chicago, IL, 52 older adults from Arizona and 135 younger adults from Augusta, GA. Correlations between fat scores and fat intakes measured by multiple food records or recalls or by more extensive food frequency questionnaires ranged from 0.33 to 0.60, similar to results from other published questionnaire validation studies. Correlations with percentage of energy from fat were lower (0.26 to 0.42), except for the Chicago population, for which there was no correlation (-0.02). There was no systematic variation in correlations among other subgroups defined by demographic and health-related characteristics, including race (black vs. white). Most, but not all, of the substantial differences in fat intakes among subgroups were identified by the questionnaire. The questionnaire will not capture small differences in intakes among groups and is inappropriate when the sample size is limited or for populations with diets substantially different from the typical U.S. diets, such as the Chicago population. However, with attention to its limitations, the questionnaire is useful for surveillance.

Adolescent↗