Showing papers in "American Journal of Epidemiology in 1985"
TL;DR: Data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.
Abstract: The aim of this study was to evaluate the reproducibility and validity of a 61-item semiquantitative food frequency questionnaire used in a large prospective study among women. This form was administered twice to 173 participants at an interval of approximately one year (1980-1981), and four one-week diet records for each subject were collected during that period. Intraclass correlation coefficients for nutrient intakes estimated by the one-week diet records (range = 0.41 for total vitamin A without supplements to 0.79 for vitamin B6 with supplements) were similar to those computed from the questionnaire (range = 0.49 for total vitamin A without supplements to 0.71 for sucrose), indicating that these methods were generally comparable with respect to reproducibility. With the exception of sucrose and total carbohydrate, nutrient intakes from the diet records tended to correlate more strongly with those computed from the questionnaire after adjustment for total caloric intake. Correlation coefficients between the mean calorie-adjusted intakes from the four one-week diet records and those from the questionnaire completed after the diet records ranged from 0.36 for vitamin A without supplements to 0.75 for vitamin C with supplements. Overall, 48% of subjects in the lowest quintile of calorie-adjusted intake computed from the diet records were also in the lowest questionnaire quintile, and 74% were in the lowest one of two questionnaire quintiles. Similarly, 49% of those in the highest diet record quintile were also in the highest questionnaire quintile, and 77% were in the highest one or two questionnaire quintiles. These data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.
4,012 citations
TL;DR: It is found that the establishment of intensive infection surveillance and control programs was strongly associated with reductions in rates of nosocomial urinary tract infection, surgical wound infection, pneumonia, and bacteremia between 1970 and 1975-1976, after controlling for other characteristics of the hospitals and their patients.
Abstract: In a representative sample of US general hospitals, the authors found that the establishment of intensive infection surveillance and control programs was strongly associated with reductions in rates of nosocomial urinary tract infection, surgical wound infection, pneumonia, and bacteremia between 1970 and 1975-1976, after controlling for other characteristics of the hospitals and their patients. Essential components of effective programs included conducting organized surveillance and control activities and having a trained, effectual infection control physician, an infection control nurse per 250 beds, and a system for reporting infection rates to practicing surgeons. Programs with these components reduced their hospitals' infection rates by 32%. Since relatively few hospitals had very effective programs, however, only 6% of the nation's approximately 2 million nosocomial infections were being prevented in the mid-1970s, leaving another 26% to be prevented by universal adoption of these programs. Among hospitals without effective programs, the overall infection rate increased by 18% from 1970 to 1976.
1,937 citations
TL;DR: New methods of quantifying the physical activity habits of communities were developed which are practical for large health surveys, provide information on the distribution of activity habits in the population, can detect changes in activity over time, and can be compared with other epidemiologic studies of physical activity.
Abstract: Previous measures of physical activity for epidemiologic studies were considered inadequate to meet the needs of a community-based health education trial. Therefore, new methods of quantifying the physical activity habits of communities were developed which are practical for large health surveys, provide information on the distribution of activity habits in the population, can detect changes in activity over time, and can be compared with other epidemiologic studies of physical activity. Independent self-reports of vigorous activity (at least 6 metabolic equivalents (METs) ), moderate activity (3-5 METs), and total energy expenditure (kilocalories per day) are described, and the physical activity practices of samples of California cities are presented. Relationships between physical activity measures and age, education, occupation, ethnicity, marital status, and body mass index are analyzed, and the reliabilities of the three activity indices are reported. The new assessment procedure is contrasted with nine other measures of physical activity used in community surveys.
1,723 citations
TL;DR: A straightforward and unified approach is presented for the calculation of the population attributable risk per cent in the general multivariate setting, with emphasis on using data from case-control studies, so that risks need not be estimated separately in a large number of strata.
Abstract: A straightforward and unified approach is presented for the calculation of the population attributable risk per cent (etiologic fraction) in the general multivariate setting, with emphasis on using data from case-control studies. The summary attributable risk for multiple factors can be estimated, with or without adjustment for other (confounding) risk factors. The relation of this approach to procedures in the literature is discussed. Given values of the relative risks for various combinations of factors, all that is required is the distribution of these factors among the cases only. The required information can often be estimated solely from case-control data, and in some situations relative risk estimates from one population can be applied to calculation of attributable risk for another population. The authors emphasize the benefits to be obtained from logistic regression models, so that risks need not be estimated separately in a large number of strata, some of which may contain inadequate numbers of individuals. This approach allows incorporation of important interactions between factors, but does not require that all possible interactions be included. The approach is illustrated with data on four risk factors from a pair-matched case-control study of participants in a multicenter breast cancer screening project.
1,195 citations
TL;DR: The physical activity recall provides useful estimates of habitual physical activity for research in epidemiologic and health education studies, and changes in energy expenditure were associated with changes in maximal oxygen uptake and body fatness.
Abstract: Assessment of habitual physical activity in epidemiologic and health education studies has been difficult. A seven-day physical activity recall interview was developed and administered in a community health survey, a randomized clinical trial, and two worksite health promotion programs during 1979-1982. These studies were conducted in several populations in California, Texas, Pennsylvania, and New Jersey. Energy expenditure estimates from the physical activity recall conformed to expected age- and sex-specific values in the cross-sectional community survey. Estimates of energy expenditure were also congruent with other questions on physical activity and job classification. In a randomized, one-year exercise trial, the physical activity recall detected increases in energy expenditure in the treated group and was positively associated with miles run during training (p less than 0.05). Changes in energy expenditure were associated with changes in maximal oxygen uptake (VO2max (r = 0.33, p less than 0.05) and body fatness (r = -0.50, p less than 0.01) at six months, and in high density lipoprotein-cholesterol (r = 0.31, p less than 0.05) and triglyceride (r = -0.41, p less than 0.01) at one year. The physical activity recall detected significant (p less than 0.01) increases in energy expenditure in treatment groups in two worksite health promotion projects. These data suggest that the physical activity recall provides useful estimates of habitual physical activity for research in epidemiologic and health education studies.
1,136 citations
TL;DR: The Baltimore-Washington Infant Study is a regional epidemiologic study of congenital heart disease and the data of the New England Infant Cardiac Program showed similar occurrences of major morphologic abnormalities, suggesting that these are stable basic estimates in the eastern United States.
Abstract: The Baltimore-Washington Infant Study is a regional epidemiologic study of congenital heart disease. Among Infants born in the study area in 1981 and 1982, 664 had a diagnosis of congenital heart disease confirmed in the first year of life by echocardiography, cardiac catheterization, cardiac surgery, or autopsy. The prevalence rate was 3.7/1,000 livebirths for all cases and 2.4/1,000 livebirths for cases confirmed by invasive methods only. Diagnosis-specific prevalence rates of congenital heart disease are compared with those of eight previous case series. Changing diagnostic categorizations in the time span covered and methodological differences resulted in great variation of the data. However, the data of the New England Infant Cardiac Program which used the same case discovery methods showed similar occurrences of major morphologic abnormalities, suggesting that these are stable basic estimates in the eastern United States. For all case series, the rate of confirmed congenital heart disease was approximately 4/1,000 livebirths over the 40-year time span.
940 citations
TL;DR: If adjustments are made for the accuracy of the diagnostic method, the increasing nationwide secular trend, and the number of nosocomial infections in nursing homes, however, as many as 4 million nosocomIAL infections per year may now be occurring.
Abstract: From a random sample of patients and hospitals and extrapolation ratios derived from the best available sources of data, the authors estimate that the nationwide nosocomial infection rate among the 6,449 acute-care US hospitals in 1975-1976 was 5.7 nosocomial infections per 100 admissions and that over 2 million nosocomial infections occurred in a 12-month period in these hospitals. Nosocomial urinary tract infections constituted 42% of the infections, surgical wound infections 24%, nosocomial pneumonia 10%, nosocomial bacteremia 5%, and nosocomial infections at all other sites 19%. If adjustments are made for the accuracy of the diagnostic method, the increasing nationwide secular trend, and the number of nosocomial infections in nursing homes, however, as many as 4 million nosocomial infections per year may now be occurring. This greatly exceeds previous estimates and calls for timely and accurate vital statistics on the problem.
713 citations
TL;DR: The authors used information collected on 58,498 patients undergoing operations in 1970 to develop a simple multivariate risk index and found that a subgroup, consisting of half the surgical patients, can be identified in whom 90% of the surgical wound infections will develop.
Abstract: To predict the likelihood that a patient will develop a surgical wound infection from several risk factors, the authors used information collected on 58,498 patients undergoing operations in 1970 to develop a simple multivariate risk index. Analyzing 10 risk factors with stepwise multiple logistic regression techniques, they developed a model combining information on four of the risk factors to predict a patient's probability of getting a surgical wound infection. Then, with information collected on another sample of 59,352 surgical patients admitted in 1975-1976, the validity of this index as a predictor of surgical wound infection risk was verified. With the simplified index, a subgroup, consisting of half the surgical patients, can be identified in whom 90% of the surgical wound infections will develop. By the inclusion of factors measuring the risk due to the patient's susceptibility as well as that due to the level of wound contamination, the simplified index predicts surgical wound infection risk about twice as well as the traditional classification of wound contamination (Goodman-Kruskal G = 0.67 vs. 0.36, p less than 0.0001). Use of this new index might substantially increase the efficiency of routine surgical wound infection surveillance and control.
697 citations
TL;DR: Foods sometimes overlooked as important sources are found in some instances to be quantitatively important to population intake, such as spaghetti dishes as an independent source of carotenoids.
Abstract: Dietary data from 11,658 adult respondents in the second National Health and Nutrition Examination Survey were used to provide quantitative information regarding the contribution of specific foods to the total population intake of the following 10 nutrients: vitamin A, thiamine, riboflavin, niacin, vitamin C, iron, phosphorus, calcium, sodium, and potassium. Data are reported in the companion paper regarding the number of adults in the US population consuming each of 147 food items, representing all foods reported by these respondents. The percentage of total nutrient intake which each food provides is presented for the top 50 contributors of each of the nutrients listed above. Foods sometimes overlooked as important sources are found in some instances to be quantitatively important to population intake, such as spaghetti dishes as an independent source of carotenoids. These data should be useful to epidemiologists with a substantive interest in dietary etiologies or a methodological interest in the development of dietary assessment instruments. In addition, they may be useful to health care planners or nutrition educators.
488 citations
TL;DR: Dietary data from 11,658 adult respondents in the second National Health and Nutrition Examination Survey were used to provide quantitative information regarding the contribution of specific foods to the total population intake of the following nutrients: calories, protein, carbohydrate, total fat, saturated fat, oleic acid, linoleic acid and cholesterol.
Abstract: Dietary data from 11,658 adult respondents in the second National Health and Nutrition Examination Survey were used to provide quantitative information regarding the contribution of specific foods to the total population intake of the following nutrients: calories, protein, carbohydrate, total fat, saturated fat, oleic acid, linoleic acid, and cholesterol. The percentage of total nutrient intake which each food provides is presented for the top 50 contributors of each of these nutrients, as well as the proportion of the population consuming them. These data may provide a basis for the selection of foods to be included in dietary assessment instruments. They may also be useful to health care planners or nutrition educators.
404 citations
TL;DR: Serum uric acid relationship with myocardial infarction was equally strong in both sexes, even correcting for antihypertensive treatment, and in multivariate analysis, including age, systolic blood pressure, relative weight, cigarette smoking, and serum cholesterol, serum uric Acid did not add independently to the prediction of coronary heart disease.
Abstract: Uric acid values were obtained on subjects of the original Framingham cohort at their fourth and 13th biennial examinations. The mean uric acid value for men was 5.0 mg/dl at the fourth examination and 5.7 mg/dl at examination 13 and was 3.9 mg/dl and 4.7 mg/dl, respectively, for women. This secular trend was due to both "laboratory drift" and increasing use of diuretics. Serum uric acid values were consistently higher in subjects of both sexes who were taking antihypertensive drugs at both examinations. Serum uric acid values correlated with systolic and diastolic blood pressure in both sexes; the relationship was stronger in women than in men and for systolic than for diastolic pressure. Correlations were stronger at examination 4 than at examination 13 when more antihypertensive treatment was used. Examination 4 serum uric acid predicted the subsequent development of coronary heart disease, in general, and myocardial infarction, in particular, but not angina pectoris. The uric acid relationship with myocardial infarction was equally strong in both sexes, even correcting for antihypertensive treatment. However, in multivariate analysis, including age, systolic blood pressure, relative weight, cigarette smoking, and serum cholesterol, serum uric acid did not add independently to the prediction of coronary heart disease.
TL;DR: The applications of Poisson regression analysis to problems of summarizing relative risk and disease rate modeling are illustrated with examples of cancer incidence and mortality data, including an example of a nonlinear model predicted by the multistage theory of carcinogenesis.
Abstract: Summarizing relative risk estimates across strata of a covariate is commonly done in comparative epidemiologic studies of incidence or mortality. Conventional Mantel-Haenszel and rate standardization techniques used for this purpose are strictly suitable only when there is no interaction between relative risk and the covariate, and tests for interaction typically are limited to examination for departures from linearity. Poisson regression modeling offers an alternative technique which can be used for summarizing relative risk and for evaluating complex interactions with covariates. A more general application of Poisson regression is its utility in modeling disease rates according to postulated etiologic mechanisms of exposures or according to disease expression characteristics in the population. The applications of Poisson regression analysis to problems of summarizing relative risk and disease rate modeling are illustrated with examples of cancer incidence and mortality data, including an example of a nonlinear model predicted by the multistage theory of carcinogenesis.
TL;DR: It is hypothesized that a 20% decrease in cardiovascular Disease risk will lead to a significant decline in cardiovascular disease event rates in two treatment communities compared with three reference communities as a result of a six-year intervention program of community-wide health education and organization.
Abstract: The Stanford Five-City Project is a large experimental field study of community health education for the prevention of cardiovascular disease. It will provide data on fundamental questions in cardiovascular disease epidemiology, communication, health education, behavior change, and community organization, and will also test the ability of a potentially cost-effective program to prevent cardiovascular disease at the community level. This paper describes the purposes, hypotheses, design, and methods of the Five-City Project as a reference for future papers describing results. It is hypothesized that a 20% decrease in cardiovascular disease risk will lead to a significant decline in cardiovascular disease event rates in two treatment communities compared with three reference communities as a result of a six-year intervention program of community-wide health education and organization. Risk factor change will be assessed through four surveys of independent samples and in a repeatedly surveyed cohort. Cardiovascular disease event rates will be assessed through continuous community surveillance of fatal and nonfatal myocardial infarction and stroke.
TL;DR: This study describes the development of benign prostatic hyperplasia among 2,036 volunteers in the Veterans Administration Normative Aging Study, a longitudinal study of human aging situated in Boston.
Abstract: This study describes the development of benign prostatic hyperplasia among 2,036 volunteers in the Veterans Administration Normative Aging Study, a longitudinal study of human aging situated in Boston. Men were followed from enrollment in the study (between 1961 and 1970) until their last examination prior to May 15, 1982. Two indications of benign prostatic hyperplasia were considered: 1) a clinical diagnosis made at a uniform physical examination, and 2) surgical treatment. Incidence rates for both a clinical diagnosis and surgery for benign prostatic hyperplasia increased through the eighth decade. Life table analysis estimated the lifetime probability of surgical treatment to be 0.29. Known risk factors for cardiovascular disease and diabetes as well as marital and socioeconomic status, religion, cigarette smoking and alcohol and coffee consumption were evaluated as risk factors. Controlling for age in proportional hazards models, statistically significant predictors of surgery were prior clinical diagnosis, lower socioeconomic status, Jewish religion, and not currently smoking cigarettes; whereas only body mass index was a significant predictor of a clinical diagnosis. Although a prior clinical diagnosis was an important predictor of surgery (adjusted odds ratio 3.52, 95% confidence interval = 1.93-6.42), this diagnosis is neither sensitive nor specific in its association with surgery.
TL;DR: The relationship between blood pressure and blood lead levels in the second National Health and Nutrition Examination Survey (1976-1980) has been examined and findings are consistent with current epidemiologic and animal studies, indicating that a causal relationship is probable.
Abstract: The relationship between blood pressure and blood lead levels in the second National Health and Nutrition Examination Survey (1976-1980) has been examined for white males aged 40-59 years. After adjustment for age, body mass index, nutritional factors, and blood biochemistries in a multiple linear regression model, the relationship of systolic and diastolic blood pressures to blood lead levels was statistically significant (p < 0.01). There was no evidence of a threshold blood lead level for this relationship. Although these data alone do not prove a causal relationship between low blood lead levels and blood pressure, the findings are consistent with current epidemiologic and animal studies, indicating that a causal reationship is probable. To examine the potential health risks, the multiple logistic risk factor coefficients from the Pooling Project and Framingham studies were used to predict the impact of the 37% decrease in mean blood lead levels which occurred in adult white males from 1976 to 1980. As a result of this blood lead decrease, the calculations predicted a 4.7% decrease in the incidence of fatal and nonfatal myocardial infarction over 10 years, a 6.7% decrease in the incidence of fatal and nonfatal strokes over 10 years, and a 5.5% decreasemore » in the incidence of death from all causes over 11.5 years. In addition, as a result of this blood lead decrease, the predicted number of white males in this age group with hypertension (diastolic blood pressure greater than or equal to 90 mmHg) decreased by 17.5%.« less
TL;DR: Apparent contrasts in symptoms associated with hepatitis A infection in adults and children suggest a basic age-dependent difference in immune response to such infection.
Abstract: Hepatitis A virus infection is often described as mild or asymptomatic, particularly in children. The failure of most adults who are found to be immune to remember symptoms of an illness suggestive of hepatitis A virus supports this belief. In 1982, two large outbreaks occurred in well documented populations of military personnel. These outbreaks were each extensively studied epidemiologically and serologically. It was found that 28/29 (96.6%) hepatitis A infections recognized prior to immune serum globulin in Outbreak A and 35/46 (76.1%) infections in Outbreak A were symptomatic. Symptomatic cases failed to occur beyond eight days of immune serum globulin administration to these predominantly susceptible groups. Between 40 and 70% of patients were icteric. Apparent contrasts in symptoms associated with hepatitis A infection in adults and children suggest a basic age-dependent difference in immune response to such infection.
TL;DR: It was found that consumption of dietary fiber was associated with decreased risk of gastric cancer; the odds ratio estimate of trend was 0.40/10 g average daily intake of fiber, and a number of dietary components seem to be implicated in the pathogenesis of stomach cancer.
Abstract: A case-control study of diet and stomach cancer was conducted during 1979-1982 in Toronto, Winnipeg, and St. John's Canada. Two hundred forty-six histologically verified cancer cases were individually matched by age, sex, and area of residence to 246 randomly selected population controls. Daily nutrient consumption values were calculated from quantitative diet history questionnaire data through use of the US Department of Agriculture Food Composition Data Bank, which was extended and modified for Canadian items. For the analysis, continuous conditional logistic regression methods were used. It was found that consumption of dietary fiber was associated with decreased risk of gastric cancer; the odds ratio estimate of trend was 0.40/10 g average daily intake of fiber (i.e., 0.40(1.5)/15 g, etc.) (p less than 10(-8)). Also, average daily consumption of nitrite, chocolate, and carbohydrate was associated with increasing trends in risk, with odds ratio estimates, respectively, 2.6/mg (p less than 10(-4)), 1.8/10 g (p less than 10(-4)), and 1.5/100 g (p = 0.015). While citrus fruit intake appeared to be somewhat protective (odds ratio = 0.75/100 g daily average, p = 0.0056), vitamin C intake was less so, and vitamin E not at all. Thus, a number of dietary components seem to be implicated in the pathogenesis of stomach cancer.
TL;DR: Age-specific infection rates determined by serology for the 1976-1977 and 1977-1978 influenza seasons confirmed the consistently high rates for type A (H3N2) in children with some fall-off with increasing age, as well as the operation of a selection mechanism in the former.
Abstract: The occurrence of influenza was followed in Tecumseh, Michigan during the five year period 1976-1981 by identifying onset of acute respiratory illness and by virus isolation and serology. Type B outbreaks were observed in 1976-1977 and 1979-1980, type A (H3N2) in 1977-1978 and 1980-1981, and type A (H1N1) viruses in 1977-1978, 1978-1979, and 1980-1981. Evidence of low level circulation of viruses in the year preceding an outbreak was not obtained. Age-specific isolation rates from specimens collected by the community physicians differed from age-specific isolation rates from specimens collected from the surveillance, suggesting the operation of a selection mechanism in the former. Symptoms associated with virus isolation were strongly influenced by age. Within age groups, several variables, especially median duration, indicated type A (H3N2) had produced the most severe illnesses, type A (H1N1) the mildest, with type B intermediate. Age-specific infection rates determined by serology for the 1976-1977 and 1977-1978 influenza seasons confirmed the consistently high rates for type A (H3N2) in children with some fall-off with increasing age. Type A (H1N1) rates peaked in children aged 5-19 years and type B in children aged 5-14 years. This may be related in part to insensitivity of the hemagglutination inhibition test in those under age 5 years. Infection with type A (H1N1) was detected at low frequency in adults. Pathogenicity was calculated based on the serologic data. It was estimated for all ages combined that, at a minimum, type A (H3N2) infection produced febrile illness in 25% of cases and type B infection produced respiratory illness in 34% of cases.
TL;DR: Questions are raised regarding the robustness of the Type A hypothesis in its present form and the validity of procedures used to assess behavior patterns in the Multiple Risk Factor Intervention Trial.
Abstract: Behavior pattern was assessed by interview for 3,110 men at eight centers in the Multiple Risk Factor Intervention Trial (1973-1976). The Type A pattern was not significantly associated with risk of first major coronary events (coronary death and definite nonfatal myocardial infarction) after a mean follow-up of 7.1 years. Crude relative risks for Types A1-A2 versus X-B were 1.08 in usual care, 0.82 in special intervention, and 0.92 overall. Adjustment for age, blood pressure, cigarette smoking, serum cholesterol, consumption of alcohol, and educational attainment yielded relative risks of 0.99 in usual care, 0.81 in special intervention, and 0.87 overall (95% confidence interval = 0.59-1.28). The Jenkins Activity Survey Type A score, obtained for 12,772 men at all 22 centers, was also not significantly associated with risk of first major coronary events. Overall, crude risks in the lowest (Type B) through highest (Type A) quintiles of the score's distribution were 5.0%, 4.4%, 4.0%, 4.3%, and 4.1%, respectively. The proportional hazards regression coefficient, adjusted for the variables listed above, was -0.006 (95% confidence interval = -0.015-0.003). These results raise questions regarding the robustness of the Type A hypothesis in its present form. Further studies are needed to investigate these questions and to evaluate the validity of procedures used to assess behavior patterns.
TL;DR: Although energy expenditure was generally low in this population of 25- to 74-year-old residents, greater leisure time physical activity for the most part was associated with lower coronary risk factors.
Abstract: Energy expenditure in leisure time physical activity was measured using the Minnesota Leisure Time Physical Activity Questionnaire in a probability sample of 25- to 74-year-old residents of the seven-county metropolitan area of Minneapolis-St. Paul, Minnesota. Geometric mean estimates of leisure time physical energy expenditure were 193 kcal per day for men and 111 kcal per day for women. Only 34% of men and 17% of women expended 2,000 kcal or more per week in leisure time physical activity. Energy expenditure, especially in heavy intensity activities, declined with age, more so for women than men. Significant associations were observed between leisure time physical activity, particularly heavy intensity activity, and other coronary heart disease risk factors. Greater heavy intensity activity was associated with higher education (r = 0.14 to 0.26), greater Type A behavior (r = 0.14 to 0.15), higher serum high density lipoprotein (HDL) cholesterol levels (r = 0.09 to 0.10), lower serum thiocyanate (r = 0.10 to -0.14), lower body mass index (r = -0.10 to -0.11), lower heart rate (r = -0.07 to -0.10), and lower systolic blood pressure (r = -0.06 to -0.09). Thus, although energy expenditure was generally low in this population, greater leisure time physical activity for the most part was associated with lower coronary risk factors.
TL;DR: The only major difference between patients with dementia of the Alzheimer type and controls was a significantly greater occurrence of antecedent head trauma in the patients, consistent with the literature on posttraumatic dementia but its importance is presently unclear.
Abstract: A case-control study to assess factors of possible etiologic significance to dementia of the Alzheimer type was conducted with 78 male cases diagnosed in 1979-1982 at the Veterans Administration Medical Center in Minneapolis, Minnesota and age-race-sex-matched hospital and neighborhood controls (14 of 16 autopsied cases were histopathologically confirmed). Information was obtained on variables relevant to vital, genetic, and immunologic hypotheses, and on possible occupational and environmental exposures, drug use, psychologic stress, smoking, and alcohol consumption. The only major difference between patients with dementia of the Alzheimer type and controls was a significantly greater occurrence of antecedent head trauma in the patients (odds ratio = 4.50). This finding is consistent with the literature on posttraumatic dementia but its importance is presently unclear.
TL;DR: Blood group did not affect an individual's risk of having a culture-proven infection with V. cholerae 01 but was directly related to the severity of disease, and individuals with the most severe diarrhea compared with those with asymptomatic infection were more often of blood group O.
Abstract: At the Matlab Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh, the authors examined the blood groups of patients hospitalized between January and September 1979 for diarrheal disease due to a variety of bacterial and viral agents. A significant association was identified only for cholera, in which cholera patients were twice as likely to have blood group O and one-ninth as likely to have blood group AB as community controls. A follow-up study of family contacts of cholera patients, carried out between September 1980 and July 1982, indicated that blood group did not affect an individual's risk of having a culture-proven infection with V. cholerae 01 but was directly related to the severity of disease. Individuals with the most severe diarrhea compared with those with asymptomatic infection were more often of blood group O (68% versus 36%, p less than 0.01) and less often of AB (0% versus 7%, p less than 0.01). It was not possible to identify the molecular basis for this genetically related protection using biologic models of cholera that are currently available. The constant selective pressure of cholera against people of O blood group may account in part for the extremely low prevalence of O group genes and the high prevalence of B group genes found among the people living in the Gangetic Delta.
TL;DR: Using maximal oxygen uptake as the measure of fitness, the authors found that the Paffenbarger Physical Activity Index, although more detailed, may be less valid than the simpler sweat induction frequency question for estimating fitness.
Abstract: Maximal oxygen uptake has been used as a measure of physical fitness. This measure increases by approximately 25% when sedentary individuals become more physically active. Oxygen uptake measurement in the laboratory or estimation in fieldwork is complex and costly with finite risk. For the present study, 36 men and 32 women completed the Paffenbarger Physical Activity Index Questionnaire, including a sweat-inducing physical activity frequency question, and had measurement of oxygen uptake during pedal ergometry. Using maximal oxygen uptake as the measure of fitness, the authors found that the Paffenbarger Physical Activity Index, although more detailed, may be less valid than the simpler sweat induction frequency question for estimating fitness. The correlations observed between the sweat question and oxygen uptake were 0.54 for males, 0.26 for females, and 0.46 for the total group. The correlations between the Physical Activity Index and oxygen uptake were 0.26 for males, 0.08 for females, and 0.29 for the total group. The regression relationship (oxygen uptake = 1.92 X (sweat days) + 23.76; standard error of estimate = 8.63 ml/kg/min) is significant for sweat versus oxygen uptake. While the confidence interval limits the practical ability to predict individual values, low cost, absence of risk, and population validity suggest that fitness can be assessed rapidly and simply for epidemiologic studies with a simple "sweat" question.
TL;DR: The findings suggest that the apparent excess risk of breast cancer among lean premenopausal women may result at least in part from easier, and thus earlier, diagnosis of less aggressive tumors.
Abstract: Although higher relative weight is generally considered to increase the risk of breast cancer, several case-control studies have suggested that the reverse may be true among premenopausal women The association between Quetelet's index (a measure of relative weight calculated as weight/height) and the subsequent incidence of breast cancer was therefore examined during four years of follow-up among a cohort of 121,964 US women who were 30-55 years of age in 1976 In contrast to women who had experienced natural menopause or bilateral oophorectomy, the incidence of breast cancer among premenopausal women decreased with higher levels of relative weight Age-adjusted relative risks for increasing quintiles of Quetelet's index were 100, 090, 090, 073, and 066 (Mantel extension test for trend = -282, p = 0005) This inverse association was not explained by known risk factors for breast cancer and was somewhat stronger when Quetelet's index was computed using reported weight at age 18 years The excess incidence of breast cancer among lean premenopausal women, however, was limited to tumors that were less than 20 cm in diameter, were not associated with metastases to lymph nodes, and were well-differentiated These findings suggest that the apparent excess risk of breast cancer among lean premenopausal women may result at least in part from easier, and thus earlier, diagnosis of less aggressive tumors
TL;DR: It was found that twice as many dietary records per individual were required to estimate the population slope within 10% of the true population correlation coefficient (rho xy).
Abstract: In this study 5,115 daily diet records were collected from 151 women on two randomly selected days per sampling month (29 days) over a two-year period. Yearly estimates of the ratios of intraindividual (sigma w2) and interindividual (sigma b2) variance components were calculated for dietary intake of 15 nutrients and for dietary intake + vitamin/mineral supplements. From one year to the next, corresponding ratios of sigma w2/sigma b2 were nearly identical. Intraindividual variation in dietary intake of all 15 nutrients was greater than interindividual variation (sigma w2/sigma b2 greater than 1). Variance component ratios for highly supplemented nutrients such as iron, vitamin C and B vitamins were less than one (sigma w2/sigma b2 less than 1). Using the ratios of sigma w2/sigma b2, it was calculated that between six and 99 repeated records measuring dietary intake and between two and 31 records measuring total intake may be needed per individual to ensure that the estimate of the population correlation (rho DF) between an individual's "usual" dietary intake or total intake of a dietary risk factor and an individual's mean or usual level of a physiologic risk factor was within 10% of the true population correlation coefficient (rho xy). It was also found that twice as many dietary records per individual were required to estimate the population slope (beta xy) within 10%. These results have serious implications for the design and analysis of prospective nutritional studies.
TL;DR: It was found that risk of cancer of the colon increased with increasing amount and proportion of time in jobs involving only sedentary or light work, and the dose-response relationship indicate that limited physical activity could be an important etiologic factor.
Abstract: The authors used data on patients aged 30-79 years admitted to the Roswell Park Memorial Institute in Buffalo, New York, 1957-1965, to compare the amount of lifetime occupational physical activity for 210 white male patients with cancer of the colon and 276 white male patients with cancer of the rectum to the lifetime occupational physical exercise of 1,431 patients with nonneoplastic nondigestive diseases. The authors found that risk of cancer of the colon increased with increasing amount and proportion of time in jobs involving only sedentary or light work. This relationship was not found for rectal cancer. These findings corroborate those of Garabrant et al. (Am J Epidemiol 1984; 119:1005-14). The strength of the associations presented here and the dose-response relationship indicate that limited physical activity could be an important etiologic factor. More inquiries need to be undertaken to study exercise in relation to other factors, such as diet, in colon cancer risk.
TL;DR: It is demonstrated that when misclassification is present, covariate control can sometimes increase net bias, even when the covariate would have been a confounder under perfect classification, and even if the covariates is a determinant of classification.
Abstract: The authors examine some recently proposed criteria for determining when to adjust for covariates related to misclassification, and show these criteria to be incorrect. In particular, they show that when misclassification is present, covariate control can sometimes increase net bias, even when the covariate would have been a confounder under perfect classification, and even if the covariate is a determinant of classification. Thus, bias due to misclassification cannot be adequately dealt with by the methods used for control of confounding. The examples presented also show that the "change-in-estimate" criterion for deciding whether to control a covariate can be systematically misleading when misclassification is present. These results demonstrate that it is necessary to consider the degree of misclassification when deciding whether to control a covariate.
TL;DR: The relative efficacy and attributes of the use of these systems to ascertain vital status are described, in part because of Social Security number discrepancies.
Abstract: Ascertainment of the vital status of individuals is of central importance to epidemiologic studies which monitor mortality as an end point. Utilizing identifying information collected in 1973-1974, the Hypertension Detection and Follow-up Program, a prospective, multicenter study, followed 25,362 individuals to determine eight-year mortality. In the most recent follow-up, there were 617 individuals whose vital status was not known. Available identifying information on these and on all 1,322 participants known to have died in 1979-1981 was submitted to the National Death Index (NDI) for possible confirmation of vital status. A subset of individuals who had Social Security numbers (490 lost to follow-up and 1,154 known deaths) was also submitted to the Social Security Administration (SSA). The NDI correctly identified 87.0% of the known deaths. Of the 1,154 known deaths (those with known Social Security numbers) submitted to both agencies, the NDI identified 93.1% and the SSA 83.6%. Significant variations by race and sex were noted in the identification rates, in part because of Social Security number discrepancies. False matches through the NDI matching process occurred for 10.4% of the known deaths. In the more restrictive SSA search, only 0.5% false matches resulted. For those lost to follow-up, vital status was ascertained in 57.1%. This paper describes the relative efficacy and attributes of the use of these systems to ascertain vital status.
TL;DR: There was good to excellent agreement for all groups when mothers' recall of personal history (past miscarriage, past pregnancy, etc.) was compared with their medical records, however, for medical intervention such as drugs and x-rays, agreement was poor.
Abstract: Using data from the Diethylstilbestrol-Adenosis (DESAD) Project, a study of the effects of diethylstilbestrol (DES) exposure during fetal life, the authors compared prenatal records with obstetric history from mother's questionnaires completed 10 or more years after the birth of their daughters. Except for the history of hospitalization and trunk x-ray, no differences were observed in agreement (questionnaire compared with record) between the group of DES-exposed mothers identified through review of their prenatal records and the comparison group of mothers who were not exposed. The authors also compared data from mothers of DES-exposed daughters who initiated their own enrollment in the study (walk-ins and referrals). To obtain prenatal records for these women, physicians were contacted. They would usually supply drug exposure data but not the other obstetric history requested. Mothers of these walk-ins and referrals had slightly better agreement between questionnaire and records when compared with the two groups identified by review of prenatal records. In general, there was good to excellent agreement for all groups when mothers' recall of personal history (past miscarriage, past pregnancy, etc.) was compared with their medical records. However, for medical intervention such as drugs and x-rays, agreement was poor. Of the DES-exposed mothers identified through review of their prenatal records, 29% could not remember whether they took DES. An additional 8% said they did not take DES when it was recorded in their charts.
TL;DR: The coronary heart disease mortality of participants in the Tecumseh study was examined with particular emphasis on the roles of diabetes and glucose tolerance as risk factors, and the predictive power of most risk factors except age itself decreased among progressively older segments of the population.
Abstract: The coronary heart disease mortality of participants in the Tecumseh study was examined with particular emphasis on the roles of diabetes and glucose tolerance as risk factors. The cohort consisted of 921 men and 937 women aged 40 years and older who did not have evident coronary heart disease at entry to the study during the period 1959-1965 and whose outcome was determined in the period 1977-1979. Previously diagnosed diabetes was a statistically significant risk factor for coronary heart disease mortality in both sexes even after controlling for systolic blood pressure, serum cholesterol, relative weight, and cigarette smoking. High blood glucose score in nondiabetics was associated with excess coronary heart disease mortality after controlling for other risk factors, but the magnitude of this effect was substantially below that of diabetes. The predictive power of most risk factors except age itself decreased among progressively older segments of the population.