Showing papers in "American Journal of Epidemiology in 1978"

Physical activity as an index of heart attack risk in college alumni

Abstract: Risk of first heart attack was found to be related inversely to energy expenditure reported by 16,936 Harvard male alumni, aged 35-74 years, of whom 572 experienced heart attacks in 117,680 person-years of followup. Stairs climbed, blocks walked, strenuous sports played, and a composite physical activity index all opposed risk. Men with index below 2000 kilocalories per week were at 64% higher risk than classmates with higher index. Adult exercise was independent of other influences on heart attack risk, and peak exertion as strenuous sports play enhanced the effect of total energy expenditure. Notably, alumni physical activity supplanted student athleticism assessed in college 16-50 years earlier. If it is postulated that varsity athlete status implies selective cardiovascular fitness, such selection alone is insufficient to explain lower heart attack risk in later adult years. Ex-varsity athletes retained lower risk only if they maintained a high physical activity index as alumni.

Estimating prevalence from the results of a screening test

Abstract: This paper deals with some basis properties of screening tests. Such tests purport to separate people with disease from people without. Minimal criteria for such a process to be a test are discussed. Various ways of judging the goodness of a test are examined. A common use of tests is to estimate prevalence of disease; frequency of positive tests is shown to be a bad estimate, and the necessary adjustmants are given.

The relationship of psychosocial factors to coronary heart disease in the Framingham study. I. Methods and risk factors.

Abstract: Questionnaires administered to 1822 members of the Framingham Heart Study from 1965 to 1967 provided measures of personality type, sociocultural mobility, situational stress and somatic strain. Clusters of questions selected by a panel of experts, and verified by item and factor analysis, formed scales of Type A behavior and other psychosocial states. The Framingham Type A behavior scale was significantly correlated with daily stress (.47), emotional lability (.43), tension (.42), anger symptoms (.34), and ambitiousness (.31). Women were less likely than men to be ambitious and to exhibit the Framingham Type A behavior, and were more likely than men to be emotionally labile, tense, and to suppress hostility. Few consistent associations were found between psychosocial stress measures and levels of blood pressure or cholesterol. Social status and marital conflicts were significantly associated with patterns of smoking. The Framingham Type A behavior pattern and other psychosocial measures were not related to the level of CHD risk, as determined by the Framingham logistic equations.

Airborne spread of measles in a suburban elementary school

Abstract: A measles epidemic in a modern suburban elementary school in upstate New York in spring, 1974, is analyzed in terms of a model which provides a basis for apportioning the chance of infection from classmates sharing the same home room, from airborne organisms recirculated by the ventilating system, and from exposure in school buses. The epidemic was notable because of its explosive nature and its occurrence in a school where 97% of the children had been vaccinated. Many had been vaccinated at less than one year of age. The index case was a girl in second grade who produced 28 secondary cases in 14 different classrooms. Organisms recirculated by the ventilating system were strongly implicated. After two subsequent generations, 60 children had been infected, and the epidemic subsided. From estimates of major physical and biologic factors, it was possible to calculate that the index case produced approximately 93 units of airborne infection (quanta) per minute. The epidemic pattern suggested that the secondaries were less infectious by an order of magnitude. The exceptional infectiousness of the index case, inadequate immunization of many of the children, and the high percentage of air recirculated throughout the school, are believed to account for the extent and sharpness of the outbreak.

Diabetes incidence and prevalence in pima indians: a 19-fold greater incidence than in rochester, minnesota

Abstract: The incidence and prevalence of diabetes mellitus were determined in 3733 Pima Indians aged 5 years or over by periodic examinations over a 10-year period. The examinations included modified glucose tolerance tests and medical record review. The age-sex adjusted prevalence rate was 21.1% (SE = 0.7%). Prevalence was low in childhood and plateaued at 40--50% in adults over 35 years of age. The age-sex adjusted incidence rate of 26.5 cases/1000 person-years (SE = 1.9) is the highest reported diabetes incidence known to the authors. Incidence increased from low levels in childhood to peak at age 40 (males) or 50 (females) and then gradually declined. Diabetes incidence was 19 times that in the predominantly white population of Rochester, Minnesota (95% confidence interval, 16 to 22 times). The high incidence rate was found despite using a more stringent diagnostic criterion than customarily employed, and was shown not be due to biased follow-up of subjects.

Differences between respondents and non-respondents in a population-based cardiovascular disease study

Abstract: The differences in cardiovascular health status between participants and non-participants were examined in a population-based cardiovascular study. Telephone interviews with non-respondents revealed generally more cardiovascular disease but less hyperlipidemia and family history of cardiovascular disease. Non-respondents did not differ regarding known hypertension, diet or drug therapy for hyperlipidemia, or egg use. Non-respondents were more likely to be cigarette smokers. Because the amount of non-respondent bias in the study was small while the response rate was high, respondents were generally representative of the target population. However, the observed differences could have produced spuriously high estimates of risk factor prevalence, low estimates of disease prevalence, and biased relative risks if the non-response rate and/or the baseline differences had been considerably larger.

Pontiac fever an epidemic of unknown etiology in a health department: i. clinical and epidemiologic aspects

Abstract: In July 1968, an explosive epidemic of acute febrile illness occurred at a county health department facility in Pontiac, Michigan. Illness characterized principally by fever, headache, myalgia, and malaise affected at least 144 persons, including 95 of 100 persons employed in the health department building. The mean incubation period was approximately 36 hours. Illness was self-limited, generally lasting from two to five days. Secondary cases did not occur in family contacts and second attacks did not consistently follow re-exposure in the building. A defective air-conditioning system was implicated as the source and mechanism of spread of the causative factor. However, extensive laboratory and environmental investigations failed to identify the etiologic agent. Since these investigations a bacterium similar to or identical with the agent responsible for Legionnaires' Disease has been isolated from guinea pigs exposed to the Pontiac health department building in 1968 as well as from guinea pigs exposed to water from the evaporative condenser. Paired sera from 32 cases of Pontiac Fever showed seroconversion or diagnostic rises in antibody titers to this bacterium.

Estimation of multiple relative risk functions in matched case-control studies

Abstract: A linear logistic model used to estimate multiple risk functions in both cohort and case-control studies is adapted for sampling plans wherein each case is matched with R controls. The resulting methodology substantially liberalizes current practice by permitting simultaneous analysis of multiple discrete and continuous risk factors. Interactions among risk factors, and between risk factors and matching variables, may be explored. Data from two studies of oesophageal cancer, one conducted among Singapore Chinese and the other on the Caspian littoral of Iran, illustrate the methods.

Erythema chronicum migrans and lyme arthritis: epidemiologic evidence for a tick vector1

Abstract: Forty-three residents of 12 contiguous Connecticut communities were identified who had the onset of erythema chronicum migrans, Lyme arthritis, or both during the summer and fall of 1977. Nine of them (21%) remembered having been bitten by a tick at the site of the initial skin lesion a median of 12 days (range 3-20) before onset; one patient brought in the tick for identification (Ixodes scapularis). Compared to 64 of their neighbors, significantly more patients had cats and farm animals, and had noted ticks on their pets and tick bites on themselves. The incidence of the illness during 1977 was 2.8 cases per 1000 residents in the three communities on the east side of the Connecticut River, compared to 0.1 cases per 1000 residents in the nine communities on the west side, a difference of almost 30-fold. Taken with the results of a concomitant acarological study on both sides of the river, these findings support the hypothesis that erythema chronicum migrans and Lyme arthritis are tick-transmitted, specifically by I. scapularis.

Distribution of alpha and alpha mating types of Cryptococcus neoformans among natural and clinical isolates.

Abstract: Survey revealed that the mating type alpha is predominant among natural and clinical isolates of Cryptococcus neoformans regardless of the serotype. The ratio of alpha and a type was about 40:1 among 105 natural isolates and 30:1 in 233 clinical isolates.

The relationship of psychosocial factors to coronary heart disease in the framingham study ii. prevalence of coronary heart disease

Abstract: In a cross-sectional study of 1822 persons aged 45 to 77 years of age, the association of 20 psychosocial scales with coronary heart disease (CHD) prevalence was assessed. Women (aged 45 to 64 years) with coronary disease scored significantly higher on the Framingham Type A behavior, emotional lability, aging worries, tension, and anger symptoms scales than women free of CHD. The prevalence of CHD was significantly higher among working women and housewives classified as Type A than as Type B behavior. Among men under 65 years, Framingham Type A behavior, aging worries, daily stress, and tension were associated with the prevalence of myocardial infarction (MI). For men and women over 65 years, marital dissatisfactions or disagreements were significantly related to the prevalence of CHD. In a multivariate analysis, the above associations were controlled for age, blood pressure, cholesterol, smoking, and other psychosocial scales. Among women under 65 years of age, Framingham Type A behavior and emotional lability remained significant discriminators of CHD prevalence. Aging worries significantly differentiated men under 65 with and without MI. Issues related to the interpretation of results from cross-sectional studies are discussed, and four hypotheses are suggested for future prospective work in this area.

A study of diet and breast cancer.

Abstract: A case-control study has been conducted in four areas in Canada in which 400 cases of breast cancer matched by age and marital status with neighborhood controls were administered a medical and dietary history questionnaire, a 24-hour recall for dietary information and a four-day diet record. The Study has produced evidence of an association between an increased intake of nutrients, especially total fat, in both pre-menopausal and post-menopausal women with breast cancer. Reasons why a weak association might have been anticipated are discussed, and it is concluded that in reality the association is stronger. Furthermore, its consistency with other evidence, both experimental and international, suggests that it is causal.

An epidemiologic study of breast cancer

Abstract: A case-control study has been conducted in four areas of Canada in which 400 cases of breast cancer matched by age and marital status with neighborhood controls were administered medical and dietary questionnaires. The study is suggestive of an increased risk of breast cancer in post-menopausal women with younger age at menarche and an increased risk with delay of age at natural menopause. No protective effect of early age at first pregnancy was demonstrated in either pre- or post-menopausal women. An increased frequency of pregnancies of four months duration or less was found in cases compared to controls and a greater frequency in pre-menopausal cases compared to controls of a history of irregular menstrual periods. In pre-menopausal women no association has been found between increased height and weight as risk factors for breast cancer. For post-menopausal women, however, a weak association with increased height has been found, while a strong association with increased weight both at the time of menopause and the 12 months preceding diagnosis has ben confirmed.

Cohort study of venereal disease. i: the risk of gonorrhea transmission from infected women to men

Abstract: Reliable data on the risk of transmission of N. gonorrhoeae would enhance our understanding of the importance of host defenses against gonorrhea and would aid in the evaluation of prophylactic measures. This paper examines the risk of transmission of gonorrhea from infected female to male and the role that variables such as race, prophylaxis and amount of exposure play in the development of gonococcal urethritis. Volunteer crew members of a large naval vessel were followed prospectively as a cohort to study their risk of acquiring gonococcal infection during a four-day liberty period in the Far East. At the same time the prevalence of N. gonorrhoeae was determined in a population of females to whom the sailors were exposed. The calculated risk of transmission per exposure with an infected partner was .19 for whites and .53 for blacks. A statistically significant relationship was noted between the risk of transmission of gonorrhea and both the number of partners and the frequency of sexual intercourse. Further, the increasing infection rate with increasing numbers of exposures in men who had a single sex partner suggests that the majority of men are in fact susceptible to gonorrhea if the quantity of exposure is sufficient.

A comparison of dietary methods in epidemiologic studies.

Abstract: Three methods of estimating group and individual dietary consumption have been developed and assessed in a case-control study of diet and breast cancer. The methods comprised a 24-hour recall, a detailed quantitative diet history directed to the most recent two-month period and the two-month period six months before, and a four-day diet diary. There is a high degree of correlation between the estimates of food consumption for the controls using each of the methods. The highest estimate was obtained from the diet history, with a slightly higher estimate in the period six months before than the current period, while the lowest is found in the 24-hour recall. The latter corresponds with the same method in a Nutrition Canada Survey. It is concluded that all methods ara applicable to case-control studies, but the diet history is preferred when current food intake may be influenced by a disease.

Epidemic kepone poisoning in chemical workers

Abstract: From March 1974 through July 1975, 76 (56%) of 133 persons who had worked at a pesticide plant that produced Kepone, a chlorinated hydrocarbon insecticide, contracted a previously unrecognized clinical illness characterized by nervousness, tremor, weight loss, opsoclonus, pleuritic and joint pain, and oligospermia. Illness incidence rates for production workers (64%) were significantly higher than for nonproduction personnel (16%). The mean blood Kepone level for workers with illness was 2.53 ppm and for those without disease 0.60 ppm (p less than 0.001). Blood Kepone levels in current workers (mean, 3.12 ppm) were higher than those in former employees (1.22 ppm). Blood Kepone levels for workers in nearby businesses and for residents of a community within 1.6 km of the plant ranged from undetectable to 32.5 ppb. Illness attributable to Kepone was found in two wives of Kepone workers; there was no apparent association between frequency of symptoms and proximity to the plant in the survey of the community population.

Cigarette smoking during pregnancy and the occurrence of spontaneous abortion and congenital abnormality

Abstract: A multiple logistic regression analysis of 12,914 pregnancies and 10,523 live births, based on a mail survey of professional women in medicine, was carried out to determine the relationship between maternal cigarette smoking, and spontaneous abortion and congenital abnormality. After controlling for interfering variables (age, exposure to trace anesthetic gases, pregnancy history, and mailing response), a statistically significant increase in risk associated with maternal cigarette smoking was found for spontaneous abortions and congenital abnormalities. The risk of spontaneous abortion for the heavy smoker is estimated to be as much as 1.7 times that of the nonsmoker in certain risk groups. The risk for congenital abnormality for babies born of smoking mothers is estimated to be as much as 2.3 times that of the nonsmoker, depending on age, pregnancy history, and other factors.

Causation and disease: a chronological journey the thomas parran lecture

Abstract: A historical review of the evolution of concepts, postulates and guidelines concerning disease causation from early germ theory to current work in the area of chronic noncontagious diseases. Students and researchers in epidemiology, clinical medicine, microbiology and related fields will value discussion of changing criteria as these apply to speci

Multivariate analysis for matched case-control studies

Abstract: A multivariate method based on the linear logistic model is presented for the analysis of case-control studies with pairwise matching. This technique enables one to investigate the effect of several variables simultaneously in the analysis while allowing for the matched design. The odds ratio is used as the basic measure of risk. One is able to control for variables which are not matching variables while investigating the odds ratio for a particular factor, and to estimate the change in the odds ratio as the level of one or more interval variables changes. The computing methods used for obtaining maximum conditional likelihood estimates of the parameters of interest are modifications of standard programs for logit regression.

Incidence rates and risk factors of benign breast neoplasms

Abstract: A case-control study of benign breast disease was conducted in Greater Boston in 1968-1969. Cases were nearly all women living in the reference population who were initially diagnosed as having fibrocystic disease, fibroadenoma or a "mixed" lesion during the study period. Controls were a random sample of the entire reference population. A mail questionnaire was completed for 678 cases and for 1807 controls. For fibrocystic disease the age-standardized incidence rate was 89.4 per 100,000 woman-years; for fibroadenoma it was 32.8. Fibrocystic disease rises in incidence to age 45 and then declines sharply. The incidence rate of fibroadenoma peaks during the 20's, while that of mixed tumors has a mode at 30 to 34. Among young women, the highest rates occur in married nulliparae, but this is not so at higher ages. Neither for fibroadenoma nor fibrocystic disease was there a consistent relationship of risk with parity or with age at first birth. Fibrocystic disease risk was strongly and directly related to age at natural menopause, directly but not strongly related to an index of socioeconomic status, and was increased among women who gave a history of arthritis. Both fibrocystic disease and fibroadenoma were much less frequent in more obese women. Neither fibrocystic disease nor fibroadenoma has an epidemiologic pattern which corresponds closely to that of breast cancer. Therefore, it seems reasonable to suggest that the apparent increased risk of breast cancer among women with benign breast disease is concentrated within a subset of these women.

Daily alcohol consumption and fatal coronary heart disease.

Abstract: For a series of 568 married white men who died from coronary heart disease (CHD) and an equal number of matched controls, information was collected on a large number of variables, including daily alcohol consumption. The crude matched pair ratio estimate for any versus no daily drinking was 0.6 (95% confidence limits 0.4 to 0.7). After controlling for additional confounding variables the risk ratio for any versus no daily alcohol consumption was 0.6 (0.5--0.8). This preventive effect was restricted to light drinkers, defined as those who drank less than or equal to 59.2 ml (2 oz) of alcohol daily. These data provide strong evidence against a causal role of daily alcohol consumption in fatal CHD and are consistent with a small preventive effect of any versus no daily drinking which is attributable only to light but not heavy drinkers.

A historical and epidemiologic perspective on respiratory symptoms questionnaires.

Abstract: Since 1960 the British Medical Research Council (MRC) standardized questionnaire on respiratory symptoms has been used in epidemiologic investigations of chronic respiratory diseases. This review describes the validity, reliability, and susceptibility to bias of the MRC questionnaire. The validity of the phlegm questions as a sensitive index of sputum production has been established but adequate validation of other symptom questions has been hindered by the absence of appropriate, independent criteria for comparison. Consistency of response averages 80 per cent for symptom questions and may reach 99 per cent for reporting of smoking habits. With proper use, the results of the MRC questionnaire are not biased by the observer, by the season of administration, or by method of administration. Modification of the questionnaire by individual investigators may lead to bias when comparisons are made between studies. Because a large literature based on the MRC questionnaire is now available, any new respiratory symptoms questionnaires should be compatible with the MRC questionnaire, and should be calibrated against it.

Energy expenditure, cigarette smoking, and blood pressure level as related to death from specific diseases

Abstract: In a 22-year followup of 3686 San Francisco longshoremen, the roles of physical activity, cigarette smoking habit, and systolic blood pressure level were evaluated independently in relation to risk of death from a broad range of diseases. Smoking pattern and blood pressure status were established in 1951 and job activity was assessed annually during the followup period. Lower levels of energy expenditure predicted increased risk of fatal heart attack and perhaps of stroke. Heavy cigarette smoking predicted increased risk of death from heart attack, cancer, chronic obstructive respiratory disease, and pneumonia. Higher levels of systolic blood pressure were associated with death from all cardiovascular diseases, diabetes mellitus, and cirrhosis. Tacit to these findings: sedentary living takes its toll largely through heart disease and stroke; the toxicity of cigarette smoking is associated with a broader range of diseases, including heart attack, cancer, and respiratory disease; and higher level of blood pressure related to an even broader range of cardiovascular disease than either of the other characteristics studied.

Relation of serum lipids and lipoproteins to obesity and sexual maturity in white and black children.

Abstract: The interrelationships of serum lipids and lipoproteins with measures of body habitus and maturation stages were analyzed in a biracial population of 3151 children, ages 5--14 years. In general, triglycerides, pre-beta-lipoprotein, and beta-lipoprotein were positively correlated with body habitus and maturation while alpha-lipoprotein was negatively correlated. The relationships in most instances were more apparent in whites than in blacks, with the highest correlations observed in white boys. No significant correlations were observed between serum cholesterol and the anthropometric variables except in white boys. The most obese children tended to have higher levels of triglycerides, pre-beta-lipoprotein, and beta-lipoprotein, and lower levels of alpha-lipoprotein than the remaining population. In the total population, the multiple correlation coefficients with the children's age, race, sex weight-height index, triceps skinfold and maturation stage as the independent variables and the concentrations of the different serum variables as the dependent variables ranged from 0.04 to 0.11.

Coronary risk and estrogen use in postmenopausal women

Abstract: Of 15500 older women (aged 57-98) in a Southern California retirement community 220 who suffered a cardiologically ascertained 1st myocardial infarction (MI) constituted a case-control study of associations between estrogen (E) use and MI. A community clinic assured availability of outpatient medical charts on most cases and controls from which potential cases were selected as outlined extensively in this studys design. Exposure to E was assessed from files of E prescriptions handled by the community drug store. The study was limited to MI occurring while in residence; only 1st episodes were eligible. The estimated mean daily dose in mg-equivalents of conjugated equine E (the majority did not use synthetic E) was .408 for cases and .315 for controls and the mean duration of most recent use by cases was 72 days; by controls 87 days. At some time during the study interval 30.1% of cases and 33.1% of controls had used oral E. No significant positive or negative association between E use and MI was found in the entire sample adjusted for age diabetes and hypertension and the summary estimate of relative risk was .86. Lower doses shorter use-duration and age-related risks may account for the lack of association. A significant connection between hypertension and MI was found.