T Byers

University of Colorado, Denver, Colorado, United States

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Publications (68)641.25 Total impact

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    ABSTRACT: to evaluate the effectiveness of a cardiovascular disease (CVD) risk factor reduction program for financially disadvantaged women. The program included cholesterol and blood pressure assessments and tailored physical activity and nutrition interventions. Women who attended selected National Breast and Cervical Cancer Early Detection Program sites in North Carolina and Massachusetts received either enhanced physical activity and nutrition interventions (EI) or minimum interventions (MI). The effectiveness of EI was assessed by pooling data from the North Carolina and Massachusetts projects after 1 year, and a mixed models analysis of covariance was used to compare changes in CVD risk factors across groups. The blood pressure, total cholesterol, and high-density lipoprotein cholesterol profiles of both groups improved, body weight was maintained, and smoking declined. The 10-year estimated coronary heart disease death rate (per 1,000 women) at baseline was 64.8 for the El group and 61.9 for the MI group. The rate declined by 3.5 deaths per 1,000 for the EI and 0.7 per 1,000 for the MI. Although the decline was statistically significant for the EI group, the difference between groups was not significant. Further lifestyle intervention research targeting financially disadvantaged women is needed.
    No preview · Article · Feb 2001 · Journal of the American Medical Women's Association (1972)
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    ABSTRACT: Updates to the American Cancer Society (ACS) guidelines regarding screening for the early detection of prostate, colorectal, and endometrial cancers, based on the recommendations of recent ACS workshops, are presented. Additionally, the authors review the "cancer-related check-up," clinical encounters that provide case-finding and health counseling opportunities. Finally, the ACS is issuing an updated narrative related to testing for early lung cancer detection for clinicians and individuals at high risk of lung cancer in light of emerging data on new imaging technologies. Although it is likely that current screening protocols will be supplanted in the future by newer, more effective technologies, the establishment of an organized and systematic approach to early cancer detection would lead to greater utilization of existing technology and greater progress in cancer control.
    No preview · Article · Nov 2000 · CA A Cancer Journal for Clinicians
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    ABSTRACT: To estimate the effect of intentional weight loss on mortality in overweight individuals with diabetes. We performed a prospective analysis with a 12-year mortality follow-up (1959-1972) of 4,970 overweight individuals with diabetes, 40-64 years of age, who were enrolled in the American Cancer Society's Cancer Prevention Study I. Rate ratios (RRs) were calculated, comparing overall death rates, and death from cardiovascular disease (CVD) or diabetes in individuals with and without reported intentional weight loss. Intentional weight loss was reported by 34% of the cohort. After adjustment for initial BMI, sociodemographic factors, health status, and physical activity, intentional weight loss was associated with a 25% reduction in total mortality (RR = 0.75; 95% CI 0.67-0.84), and a 28% reduction in CVD and diabetes mortality (RR = 0.72; 0.63-0.82). Intentional weight loss of 20-29 lb was associated with the largest reductions in mortality (approximately 33%). Weight loss >70 lb was associated with small increases in mortality Intentional weight loss was associated with substantial reductions in mortality in this observational study of overweight individuals with diabetes.
    Preview · Article · Nov 2000 · Diabetes Care
  • T Byers
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    ABSTRACT: Randomized controlled trials are regarded as the most definitive of study designs. The randomized controlled trials that have tested nutritional factors for cancer prevention are reviewed. Trials that have tested the effects of nutrients given as high-dose supplements have been largely disappointing, typically showing either no or harmful effects. Possible benefits of vitamin E for prostate cancer prevention and selenium for prostate, colorectal, and lung cancer prevention have emerged only as secondary endpoints in trials conducted for other purposes; confirmatory new trials for these nutrients are now underway or are planned. The limitations of both past and current randomized controlled trials for studying diet-cancer relationships are discussed. The disappointing findings that have emerged from short-term studies of high-dose supplements cannot be interpreted as direct tests of the diet-cancer relationship because high-dose supplements cannot fully simulate the effects of whole foods on cancer risk. As we await findings from current and future trials, we should not forget that the ample evidence from observational epidemiologic research--suggesting that diets rich in fruits and vegetables can reduce the risk of many of the most common cancers--can provide a sound basis for nutritional recommendations aimed at reducing cancer risk.
    No preview · Article · Nov 1999 · CA A Cancer Journal for Clinicians
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    ABSTRACT: To assess prospectively the relation between body mass index, weight gain, repeated intentional weight losses, and the risk of self-reported hypertension, the authors studied 46, 224 women who were participants in the Nurses Health Study II, who were free of hypertension in 1993, and who completed questions on intentional weight losses between 1989 and 1993. Women who reported they had intentionally lost ≥20 lbs (9 kg) ≥3 times were classified as severe weight cyclers. Women who had intentionally lost ≥10 lbs (4.5 kg) ≥3 times, but who did not meet the criteria for severe weight cycling, were classified as mild weight cyclers. Between 1993 and 1995, 1, 107 incident cases of diagnosed hypertension were reported. Body mass index and weight gain, but not weight cycler status, were independently associated with the development of hypertension. For each 10 Ib (4.5 kg) gain in weight between 1989 and 1993, the risk of hypertension increased 20% (odds ratio (OR) = 1.20, 95% confidence interval (Cl) 1.15, 1.24). After adjustment for body mass index and weight gain, the risks associated with mild weight cycling (OR = 1.15, 95% Cl 1.00, 1.33) and severe weight cycling (OR = 1.13, 95% Cl 0.79, 1.61) were small and not significant. Thus, the results of this study offer support for the current weight guidelines and provide further evidence of the health risks associated with excessive weight and weight gain. However, these data do not suggest an independent effect of weight cycling on risk of hypertension. Am J Epidemiol 1999; 150: 573-9.
    Full-text · Article · Oct 1999 · American Journal of Epidemiology
  • T Byers · J Mouchawar · J Marks · B Cady · N Lins · G M Swanson · D G Bal · H Eyre
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    ABSTRACT: Cancer incidence and mortality rates both began to decline in the U. S. in the early 1990s. Recognizing the unprecedented potential benefits of accelerating this decline, the American Cancer Society (ACS) has set ambitious challenge goals for the American public for a 25% reduction in cancer incidence rates and a 50% reduction in cancer mortality rates by the year 2015. This analysis examined the feasibility of reaching those goals by estimating future changes in cancer rates that can result from past and future reductions in cancer risk factors. Estimates for future declines in cancer risk factors in the U. S. under alternative scenarios were applied to conservative population-attributable risk estimates for cancer incidence and mortality rates in 1990 to estimate cancer rate trends in the year 2015. If the current trends toward a decline in the prevalence of cancer risk factors continue over the next decade, by the year 2015 one can expect a 13% decline in cancer incidence rates and a 21% decline in cancer mortality rates below their 1990 levels. With redoubled efforts to reduce the prevalence of known cancer risk factors further, by the year 2015 cancer incidence rates could be reduced by 19% and cancer mortality rates reduced by 29%. Such redoubled efforts would equate to approximately 100,000 cancer cases and 60,000 cancer deaths prevented each year by the year 2015. Past reductions in cancer risk factors in the U.S. population have led to recent declines in the rates of cancer incidence and mortality in the U.S. Redoubled efforts to act on current knowledge regarding how to prevent, detect, and treat cancer can result in attaining approximately 80% of the ACS challenge goal for cancer incidence rates and 60% of the ACS challenge goal for cancer mortality rates by the year 2015. New findings from cancer research are needed and will have to be applied quickly if the ACS challenge goals are to be met fully.
    No preview · Article · Sep 1999 · Cancer
  • T Byers · B Lyle
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    ABSTRACT: This statement summarizes the key points of discussion among a group of nutritional epidemiologists who met in Washington, DC, for 2 d in October of 1997 to reflect on the role of nutritional epidemiology in the development of dietary recommendations for the public. Although imprecision in the measurement of diet places limits on nutritional epidemiology, no other field of nutritional science can provide direct information on relations between nutrition and health in free-living human populations. Among the nutritional sciences, therefore, epidemiology was regarded as being critically important. Nutritional epidemiology can be improved in the future by the development of more precise measures of long-term dietary exposures, both by improved methods of self-reporting of diet and by the development of more useful biomarkers of long-term nutritional status. There is a need as well to reconsider the applicability of causal criteria as applied to nutritional epidemiology, because many of the important associations between dietary behaviors and chronic diseases cannot necessarily be expected to be either strong or to manifest linear dose-response relations. In the future, scientific evidence from the rapidly growing field of nutritional epidemiology will likely play an increasingly important role in developing nutrition policy and advice for the public.
    No preview · Article · Jul 1999 · American Journal of Clinical Nutrition
  • T Byers
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    ABSTRACT: Observations of the relations between food choices and health have been made since ancient times, but epidemiology, which can be regarded as the science of systematically studying these relations, has played a key role in official nutritional guidance only in recent years. In the past 20 y the principal goal of nutritional guidance has changed from the prevention of nutritional deficiencies to the prevention of chronic diseases. This evolving purpose of nutritional guidance has demanded that nutritional epidemiology play an increasingly important role. Although no other type of nutritional science can equal epidemiology in the relevance of either the dietary exposures or the health outcomes, substantial problems limit the ability of nutritional epidemiology to convincingly prove causal associations. The classic criteria for causation are often not met by nutritional epidemiologic studies, in large part because many dietary factors are weak and do not show linear dose-response relations with disease risk within the range of exposures common in the population. The most important problem in nutritional epidemiology in the past has been the inaccuracy of dietary assessment. In the future, an additional problem will be the proliferation of hypotheses that can be tested in multiple ways among the many subgroups of the population that can be defined by factors such as age, sex, and genotype. Future progress in our understanding of the relations between diet and health will necessitate improved methods in nutritional epidemiology and a better integration of epidemiologic methods with those used in the clinical nutritional sciences.
    No preview · Article · Jul 1999 · American Journal of Clinical Nutrition
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    ABSTRACT: Obesity and rapid weight loss in obese persons are known risk factors for gallstones. However, the effect of intentional, long-term, moderate weight changes on the risk for gallstones is unclear. To study long-term weight patterns in a cohort of women and to examine the relation between weight pattern and risk for cholecystectomy. Prospective cohort study. 11 U.S. states. 47,153 female registered nurses who did not undergo cholecystectomy before 1988. Cholecystectomy between 1988 and 1994 (ascertained by patient self-report). During the exposure period (1972 to 1988), there was evidence of substantial variation in weight due to intentional weight loss during adulthood. Among cohort patients, 54.9% reported weight cycling with at least one episode of intentional weight loss associated with regain. Of the total cohort, 20.1% were light cyclers (5 to 9 lb of weight loss and gain), 18.8% were moderate cyclers (10 to 19 lb of weight loss and gain), and 16.0% were severe cyclers (> or = 20 lb of weight loss and gain). Net weight gain without cycling occurred in 29.3% of women; net weight loss without cycling was the least common pattern (4.6%). Only 11.1% of the cohort maintained weight within 5 lb over the 16-year period. In the study, 1751 women had undergone cholecystectomy between 1988 and 1994. Compared with weight maintainers, the relative risk for cholecystectomy (adjusted for body mass index, age, alcohol intake, fat intake, and smoking) was 1.20 (95% CI, 0.96 to 1.50) among light cyclers, 1.31 among moderate cyclers (CI, 1.05 to 1.64), and 1.68 among severe cyclers (CI, 1.34 to 2.10). Weight cycling was highly prevalent in this large cohort of middle-aged women. The risk for cholecystectomy associated with weight cycling was substantial, independent of attained relative body weight.
    No preview · Article · Apr 1999 · Annals of internal medicine
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    ABSTRACT: Although 25% of US men indicate that they are trying to lose weight, the association between intentional weight loss and longevity in men is unknown. The authors analyzed prospective data from 49,337 overweight (initial body mass index > or =27) white men aged 40-64 years who, in 1959-1960, answered questions on weight change direction, amount, time interval, and intent. Vital status was determined in 1972. Proportional hazards regression estimated mortality rate ratios for men who intentionally lost weight compared with men with no weight change. Analyses were stratified by health status and adjusted for age, initial body mass index, smoking status, alcohol intake, education, physical activity, health history, and physical symptoms. Among men with no reported health conditions (n = 36,280), intentional weight loss was not associated with total, cardiovascular (CVD), or cancer mortality, but diabetes-associated mortality was increased 48% (95% confidence interval (CI) -7% to +133%) among those who lost 20 pounds (9.1 kg) or more; this increase was largely related to non-CVD mortality. Among men with reported health conditions (n = 13,057), intentional weight loss had no association with total or CVD mortality, but cancer mortality increased 25% (95% confidence interval -4% to +63%) among those who lost 20 pounds or more. Diabetes-associated mortality was reduced 32% (95% confidence interval -52% to -5%) among those who lost less than 20 pounds and 36% (95% confidence interval -49% to -20%) among those who lost more than 20 pounds. These results and those from our earlier study in women (Williamson et al., Am J Epidemiol 1995;141:1128-41) suggest that intentional weight loss may reduce the risk of dying from diabetes, but not from CVD. In observational studies, however, it is difficult to separate intentional weight loss from unintentional weight loss due to undiagnosed, underlying disease. Well-designed observational studies, as well as randomized controlled trials, are needed to determine whether intentional weight loss reduces CVD mortality.
    Preview · Article · Mar 1999 · American Journal of Epidemiology
  • M K Serdula · AH Mokdad · T Byers · P Z Siegel
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    ABSTRACT: The quantity-frequency method is commonly used to measure alcohol intake in large surveys. Because of time and space constraints, questionnaires are often shortened by combining questions on all types of alcohol into a single question. We investigated the effect of this practice using data from the Behavioral Risk Factor Surveillance System. We examined data collected from 213,842 respondents to surveys conducted by 32 states and the District of Columbia participating in the years 1987, 1988, 1989 and 1990. The 1987 and 1988 surveys asked questions about respondents' frequency and level of intake of specific alcohol-containing beverages. The 1989 and 1990 surveys asked about the frequency and quantity of intake of alcohol-containing beverages by combining all beverages into a single group. Among drinkers, the mean number of drinks per month was higher for those who were asked beverage-specific questions than for those who were asked grouped-beverage questions (men: 37.0 vs 29.6; women: 17.0 vs 13.9). Caution must be used in comparing level of alcohol intake from surveys in which beverages are not grouped identically.
    No preview · Article · Feb 1999 · Journal of studies on alcohol
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    ABSTRACT: This study compared fruit and vegetable assessments derived from 4 self-administered questionnaires. Among 102 adolescents, servings of fruits and vegetables assessed by 4 questionnaires were compared with estimates from 24-hour recalls. The prevalence of consuming 5 or more servings of fruits and vegetables a day was underestimated by the questionnaires. Questionnaires asking subjects to recall their diet over the previous year were more effective in ranking subjects (r's > or = .42) than those assessing previous-day diet (r's > or = .30). Brief assessments of fruit and vegetable intake are more useful for ranking subjects than for estimating prevalence of consumption of 5 or more servings per day.
    Full-text · Article · Aug 1998 · American Journal of Public Health
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    ABSTRACT: The authors compared interview reports with hospitalization records of participants in a nationally representative survey to determine the accuracy of self-reports of ischemic heart disease, stroke, gallbladder disease, ulcers, cataract, hip fracture, colon polyps, and cancers of the colon, breast, prostate, and lung. The study cohort consisted of 10,523 participants from the First National Health and Nutrition Examination Survey in 1971-1975 who were aged 25-74 years at the baseline examination and who completed a follow-up interview in 1982-1984. Self-reports of hospitalization for breast cancer were confirmed as accurate for 100% of cases where a hospital record was available. Self-report accuracy was also high for ischemic heart disease (84%), cataract (83%), and hip fracture (81%); it was moderate for lung cancer (78%), prostate cancer (75%), gallbladder disease (74%), colon cancer (71%), and stroke (67%); but it was low for ulcers (54%) and colon polyps (32%). Some of the self-reports of ulcers (20%), hip fracture (9%), ischemic heart disease (7%), and stroke (7%) were found to reflect diagnoses of other conditions of anatomic proximity. Accuracy of self-reports improved with higher levels of education, but was not generally related to age, gender, race, alcohol use, or smoking. The results suggest that self-reports of some diseases can be taken as accurate, but self-reports of other conditions might require medical record verification in epidemiologic follow-up studies.
    Full-text · Article · Jun 1998 · American Journal of Epidemiology
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    T Byers · K Gieseker
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    ABSTRACT: The methods used in nutritional epidemiology to study the relations between fatty acids and cancer risk include ecologic studies, case-control studies, cohort studies, and intervention trials examining either intermediate markers of cancer risk or cancer incidence. Each type of study design has its particular strengths and weaknesses. The inaccuracy of estimates of fatty acid intake from the use of dietary questionnaires linked to nutrient databases is a major limitation in nutritional epidemiology. Information on the concentrations of fatty acids in the circulation or in adipose tissue can complement estimations of dietary intake. Cancer prevention studies now underway are designed to test whole-diet effects on neoplasia and will not be able to separate the effects of specific fatty acids from those of other nutrients in the diet. The development of better intermediate markers of cancer risk could enable the use of experimental methods to assess the relation between specific fatty acids and cancer. Research findings as described in the literature are complicated both by the multiple hypotheses that can be tested when assessing fatty acid effects and by the uncertainties of multivariate adjustment. Although there are substantial obstacles to understanding the relations between fatty acid intakes and cancer risk, there is no better species than humans for inference about diet and cancer risk in people.
    Preview · Article · Jan 1998 · American Journal of Clinical Nutrition
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    Preview · Article · Nov 1997 · American Journal of Public Health
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    ABSTRACT: Although counts of leukocytes differ substantially between blacks and whites, and are predictive of ischaemic heart disease (IHD), racial differences in counts of leukocyte subpopulations have received less attention. We examined black/white differences in leukocyte subpopulations among 3467 white and 493 black 31-45 year-old-men who had previously served in the US Army. Laboratory determinations were performed at a central location during 1985-1986. Black men had an 840 cell/microliter (or 15%) lower mean total leukocyte count than did white men, largely due to a 960 cell/microliter (or 25%) lower mean neutrophil count. Although black men also had a 20% lower mean monocyte count (= 70 cells/microliter) than did white men, their mean lymphocyte count was 10% higher (approximately = 200 cells/microliter). Counts of various leukocyte subpopulations were associated with cigarette smoking, haemoglobin levels, platelet counts, and several other characteristics, but black/white differences in counts of neutrophils, lymphocytes, monocytes and other subpopulations could not be attributed to any of the examined covariates. Despite the relatively low counts of leukocytes and neutrophils among black men, their lymphocyte counts are generally higher than those among white men. It is possible that black/white differences in counts of various cell types may influence race-specific rates of IHD, and future studies should attempt to assess the importance of leukocyte subpopulations in the development of clinical disease.
    Preview · Article · Sep 1997 · International Journal of Epidemiology
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    ABSTRACT: Information about dietary behaviors, attitudes, and knowledge is important for state and local health agencies because national monitoring lacks the local representativeness and timeliness necessary to catalyze community interest and to design, target, and evaluate dietary intervention programs. Currently, however, both methods and resources are limited for surveying diet in the population of a state or community. Brief assessments are included in the Youth Risk Behavior Surveillance System for adolescents, which is conducted by state departments of education, and in the Behavioral Risk Factor Surveillance System for adults, which is operated by state departments of health. More quantitatively precise measurements are being made by a few states and communities but personnel and financial resources for such surveys are limited. Nutritionists in state and local health agencies should explore the possibility of developing public-private partnerships with food producers, retailers, and marketers to collect information about dietary determinants and behaviors in states and communities. Better standardization of dietary assessment methods is needed, as is development of better methods to identify attitudes about diet and barriers to dietary improvement. Most important, though, dietary surveillance in states and communities must be more strongly tied to intervention programs intended to improve nutrition in those populations.
    Preview · Article · May 1997 · American Journal of Clinical Nutrition
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    DA Galuska · Serdula MK · E Pamuk · P Z Siegel · T Byers
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    ABSTRACT: Using data from the Behavioral Risk Factor Surveillance System, this study describes trends in the prevalence of overweight between 1987 and 1993. 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. 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. 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.
    Preview · Article · Jan 1997 · American Journal of Public Health
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    ABSTRACT: 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. 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. 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. 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.
    Full-text · Article · May 1996 · International Journal of Epidemiology
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    E S Ford · D S Freedman · T Byers
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    ABSTRACT: A weak positive association between male pattern baldness and ischemic heart disease has been suggested previously. The authors examined this issue by using data from the Epidemiologic Follow-up Study of the First National Health and Nutrition Examination Survey. As part of the baseline medical examination between 1971 and 1975, the presence and degree of male alopecia (none, minimal, moderate, and severe) were recorded for a subset of participants. Among 3, 932 men aged 25–76 years who had complete data, 378 deaths and 939 incident events from ischemic heart disease occurred during an average follow-up period of 14 years. Among 2,019 men who were younger than age 55 years at baseline (61 deaths and 239 incident events of ischemic heart disease), severe baldness was positively associated with ischemic heart disease mortality (rate ratio = 2.51, 95% confidence interval 1.01–6.24) and somewhat less associated with ischemic heart disease incidence (rate ratio = 1.72, 95% confidence interval 0.96–3.08). No dose-response relation with degree of baldness was seen. Arthough these findings are tempered by the absence of information concerning the type of baldness (frontal or vertex), they provide support for earlier studies that indicate male pattern baldness that occurs before age 55 years may be by some mechanism related to ischemic heart disease.
    Preview · Article · May 1996 · American Journal of Epidemiology

Publication Stats

7k Citations
641.25 Total Impact Points

Institutions

  • 2000
    • University of Colorado
      Denver, Colorado, United States
  • 1998-1999
    • University of Colorado Hospital
      Denver, Colorado, United States
    • German Institute of Human Nutrition
      Berlín, Berlin, Germany
  • 1996
    • Uppsala University
      • Department of Statistics
      Uppsala, Uppsala, Sweden
    • Uppsala University Hospital
      • Department of Oncology
      Uppsala, Uppsala, Sweden
  • 1991-1996
    • Centers for Disease Control and Prevention
      • National Center for Chronic Disease Prevention and Health Promotion
      Atlanta, Michigan, United States
  • 1994
    • National Cancer Institute (USA)
      베서스다, Maryland, United States
    • Georgia Health Sciences University
      • Department of Pediatrics
      Augusta, GA, United States
  • 1982-1988
    • University at Buffalo, The State University of New York
      • Department of Social and Preventive Medicine
      Buffalo, New York, United States