Epidemiological Study Of Risk Factors Research Articles

Bone remodeling in hip fracture.

Hip fracture incidence has shown strong upward secular trends in many societies with wide differences in age adjusted incidence between nations. Falls and reduced physical activity have emerged as the strongest risk factors in epidemiological studies, while clinical investigations have pointed to secondary hyperparathyroidism as an important candidate cause of the loss of femoral cortical bone in old age. Until recently there have been few studies performed directly on the region of interest in the proximal femur. Non-invasive methodology using 85Sr has now been developed by our group for measuring bone formation and (with concurrent serial DXA densitometry) resorption in the femoral neck. Bone turnover averaged about 8% annually in controls. A group of younger cases of femoral fracture showed similar indices of total and regional bone formation to a control group; but their resorption was higher. To further investigate this, a femoral neck bone biopsy technique has been developed which can be applied to fracture cases treated by arthroplasty. Preliminary studies have established that the anatomical asymmetry of the neck in cross-section is considerable and imposes restraints on the interpretation of smaller or incomplete femur biopsies. Prospects are quite good that, in the absence of tetracycline pre-labeling, mineralization can be studied by assessment of alkaline phosphatase-positive surfaces in cryostat sections. Moreover, such sections will permit study of other anatomically localized metabolic activities as well as antigen expression and osteocyte viability. Candidate mechanisms for the regional decline in bone quality as well as bone mass in subjects suffering hip fracture can now be investigated more effectively.

Epidemiology of low back pain

At present, although there have been many epidemiological studies of risk factors for low back pain, there are few risk factors established in prospective studies; and our understanding of them remains relatively crude. Individuals in jobs requiring manual materials handling, particularly repeated heavy lifting and lifting while twisting, are at increased risk of back pain leading to work absence. In addition, exposure to whole-body vibration and job requirements for static postures are associated with back pain. Individual trunk strength has not been consistently demonstrated as associated with back pain; although there is some suggestion that when work requirements for heavy lifting exceed individual capacities, back pain is more likely to occur. The pattern of peak age at onset in the 20's is consistent with back pain development early in working life. Among other individual characteristics, only cigarette smoking has consistently been associated with back pain; and the biological mechanism for this finding is not understood. Evidence with respect to spinal flexibility, aerobic capacity, educational attainment and other variables is suggestive but not consistent. There is some evidence that the individual's relation to work, expressed as job satisfaction or supervisor rating, is also related to work absence due to back pain. While it is possible to describe, however crudely, the characteristics placing people at risk for back pain leading to work absence and/or medical attention, the problem of predicting chronicity and thus identifying patients for more intensive clinical intervention remains unresolved. At this time, only age of the patient and certain clinical features of the back pain such as the presence of sciatic symptoms, duration of the current episode, and history of prior episodes are consistently demonstrated predictors. In chronic patients, there is suggestive evidence that spinal flexibility, trunk strength, and certain psychological characteristics such as coping skills, fear and avoidance of pain or movement, job satisfaction, attribution of fault and hysterical or hypochondriacal features are associated with treatment failure. In addition, there is suggestive evidence that the availability of alternative work placement may allow for earlier return to work than otherwise. While the availability of disability compensation in excess of usual wages may serve as a disincentive to return to work. The latter-cited remain to be verified, while findings in chronic patients remain to be tested in acute. Further, the role of physical demands of work in duration of back pain episodes has not been well studied.

Socioeconomic and behavioral correlates of body mass index in black adults: the Pitt County Study.

Obesity is more prevalent among Black women than Black men, but there is little information on the correlates of obesity in Blacks. This study describes the relations of sociodemographic factors and health behaviors to body mass index in a southern, Black population. In 1988, a community probability sample of 1784 Black adults, aged 25 to 50, was examined in Pitt County, NC. More women than men were at least 20% overweight (57% vs 36%). The relation of socioeconomic status (a composite of education and occupation) to age-adjusted body mass index level was inverse in women but not in men. Body mass index did not differ with either current energy intake or energy expenditure. Smokers and drinkers had lower age-adjusted levels than non-smokers and abstainers. Since the excess body mass index levels associated with low socioeconomic status in women could not be explained after controlling for adverse health behaviors, further epidemiologic study of risk factors for obesity in Black women is recommended.

Sodium-lithium countertransport and body fat distribution

The relationship between erythrocyte sodium-lithium countertransport (NaLi CT) and body fat distribution is analyzed in a sample (n = 101) of normotensive and untreated hypertensive men participating in an epidemiological study of coronary heart disease risk factors. NaLi CT is significantly and positively associated with both subscapular skinfold and waist to hip ratio, but not with triceps skinfold. The univariate correlation between NaLi CT and blood pressure is diminished when adjusted for body mass index and waist to hip ratio. These findings support the existence of an association between NaLi CT and central body fat distribution and suggest that the metabolic abnormalities associated with centrally distributed body fat could explain, at least in part, the association between NaLi CT and blood pressure. The maximal velocity of the sodium-lithium countertransport (NaLi CT) in erythrocytes has been reported to be directly associated with blood pressure and hypertension in numerous reports from both clinical and epidemiological studies (1–6). In most of these studies, indices of weight and/or adiposity (body mass index, in particular) have been shown to be among the most important correlates of NaLi CT (1–7). Adiposity is an important determinant of blood pressure, and there is evidence suggesting that the patterning of the fat cells in the body is linked to a number of metabolic disturbances that could lead to hypertension and an increase in other CHD risk factors (8, 9). The present report analyses the relationship between NaLi CT and body fat distribution in a sample of normotensive and untreated hypertensive men participating in an epidemiological study.

Geriatric Dentistry and Prevention: Research and Public Policy

Changing demographics, including the increase in life expectancy and the growing numbers of elderly, has focused attention on the need for dental research activities to be expanded for geriatric dentistry. The elderly are at greater risk for oral disease, since gains in longevity result in more medically compromising conditions or systemic disease with oral manifestations. Also, as edentulism decreases and as more teeth are retained by the elderly, the pattern of oral diseases and the treatment of dental conditions will be altered. Barriers to self-care and professional care must be removed, and prevention and early intervention strategies must be formulated to reduce the risk of oral disease. Risk factors for oral diseases in the elderly can be reduced by personal home-care regimens, professionally provided preventive, diagnostic, and therapeutic care, changes in high-risk behavior, and a supportive environment. Generating new information about the prevention of oral diseases and conditions that have an impact on the elderly requires a substantial research effort. A research agenda for the elderly should include: epidemiologic studies of relevant oral diseases and related risk factors; investigations of patient and provider attitudes and behavior related to oral health; studies of the relationship between general health and oral health; development and testing of preventive and treatment strategies for conditions such as xerostomia, root caries, secondary caries, and gingival recession; and studies for the evaluation of the impact of the aging population on the dental delivery system. Public policy options to support geriatric oral health care and research are limited by the Government's pre-occupation with cost containment and the lack of visibility for dental programs.(ABSTRACT TRUNCATED AT 250 WORDS)

Wilms' tumor: status report, 1990. By the National Wilms' Tumor Study Committee.

Rapid advances in the understanding of Wilms' tumor (WT) and its management are being made both in the laboratory and the clinic. Molecular genetic research has implicated loss of a tumor suppressor gene on the short arm of chromosome 11 as one of the pathways responsible for the development of the neoplasm. Preconception maternal (hair dyes) and paternal (occupation) exposures to environmental agents have been the subject of epidemiologic studies of possible risk factors. Histopathologic analyses have identified several different and less common tumor types among those previously aggregated under the WT rubric. WT itself has been subdivided into the so-called favorable histology (FH) and anaplastic forms, the prognosis being worse for the latter. Clinical research has standardized management by surgery, chemotherapy, and radiation therapy (RT) and furthered the identification of risk factors. Patients can now be stratified according to tumor type and stage, and the intensity of treatment modulated accordingly; eg, RT at low doses is used in only 25% of National Wilms' Tumor Study (NWTS) patients without distant metastases. Before the NWTS, it had been given to almost all and at higher doses. Chemotherapy, whether given pre- or postoperatively, is based on dactinomycin and vincristine with Adriamycin [( ADR] doxorubicin; Adria Laboratories, Columbus, OH) added for high-risk patients. The currently used NWTS combined modality therapy for WT patients has dramatically improved survival rates; 95% now are alive 2 years after treatment. Remaining questions are the identification of the late effects of the treatments used and the further refinement of therapy to reduce iatrogenic complications to a minimum.

The Influence of Diet on the Appearance of New Lesions in Human Coronary Arteries

The Cholesterol Lowering Atherosclerosis Study, a randomized, placebo-controlled trial of blood lipid lowering, demonstrated significant benefit in 2-year coronary angiograms. Using angiograms of subjects in the Cholesterol Lowering Atherosclerosis Study who received a placebo and 24-hour dietary recall data, we performed an epidemiologic study of risk factors for formation of new atherosclerotic lesions. Age and baseline plus on-trial lipid levels, blood pressure levels, and diet variables were included. Significant dietary energy sources were protein, carbohydrate, alcohol, total fat, and polyunsaturated fat. Each quartile of increased consumption of total fat and polyunsaturated fat was associated with a significant increase in risk of new lesions. Increased intake of lauric, oleic, and linoleic acids significantly increased risk. Subjects in the Cholesterol Lowering Atherosclerosis Study in whom new lesions did not develop increased dietary protein to compensate for reduced intake of fat by substituting low-fat meats and dairy products for high-fat meats and dairy products. These results indicate that when total and saturated fat intakes are reduced to levels recommended by the National Cholesterol Education Program, protein and carbohydrate are preferred substitutes for fat calories, rather than monounsaturated or polyunsaturated fat.

Glomerulosclerosis in the Sudden Infant Death Syndrome

In the past two decades, two groups of investigators have alleged that infants who die of the sudden infant death syndrome (SIDS) have excess numbers of sclerotic glomeruli in their kidneys. This double blind, case-control study was undertaken to test that assertion. Using microscopic sections of the kidney from 153 autopsies (99 SIDS infants and 54 control infants) in the National Institute of Child Health and Human Development (NICHD) Cooperative Epidemiologic Study of Risk Factors for SIDS, we counted relative numbers of sclerotic glomeruli in four fields of renal cortical tissue in two sections from each infant. Our results indicate that there is no difference between the two groups in regard to the proportion of sclerotic glomeruli.

An epidemiologic study of risk factors in two teenage suicide clusters

An epidemiologic study of risk factors in two teenage suicide clusters

The effects of exercise on coronary heart disease risk factors in children.

Coronary heart disease (CHD) is now recognised as a paediatric problem despite the fact that clinical symptoms of this disease do not become apparent until much later in life. Epidemiological studies of risk factors in children have now been conducted. These studies suggest that the risk factors for cardiovascular disease in adults, which include a family history of heart disease, elevated blood lipids (serum cholesterol and triglycerides), obesity, hypertension, smoking, diabetes mellitus and inadequate physical activity, can be identified in children. Several investigators have reported the existence of one or more risk factors in more than 50% of the children they have examined. It is now clear that we can detect most children who are potentially at risk for CHD. The notion of 'tracking' some of the most common CHD risk factors in children has been used in several studies. Results from this type of research indicate that children who are at the extreme end of the distribution and have high levels of blood pressure, adverse lipid levels and are obese will continue to exhibit these coronary risk factors as they grow. The research completed at present does not answer the question of whether children who exhibit a coronary-prone risk factor profile will exhibit this same profile at an age when one is most likely to develop the clinical manifestations of CHD. It does make sense, however, to identify those children who may be at risk for developing premature CHD and to initiate safe interventions such as behaviour modification, changes in diet and increases in physical activity. These have all been shown to alter risk factors which are associated with increased relative risk of CHD in adults. It should be noted that in adults regular aerobic exercise often may alter all risk factors for CHD, including hypertension and diabetes. Whether regular aerobic exercise will induce similar changes in children is not fully understood.

Respiratory symptoms in Danish farmers: an epidemiological study of risk factors.

An epidemiological study was performed with a self administered questionnaire in a representative sample of 1685 Danish farmers. The purpose of the study was to assess the prevalence of self reported asthma, wheezing during work, and symptoms of chronic bronchitis and to evaluate possible risk factors for the development of these symptoms. A response rate of 73.3% was obtained. The prevalence of asthma was 7.7% and of chronic bronchitis 23.6% in responders. The prevalence of asthma and chronic bronchitis increased from 3.6% and 17.9% in 31-50 year old farmers to 11.8% and 33.0% in 51-70 year old farmers, and from 5.5% and 17.5% in dairy farmers to 10.9% and 32.0% in pig farmers. A logistic regression analysis with correction for age and smoking habits confirmed that pig farming was a risk factor for asthma (odds ratio 2.03), chronic bronchitis (odds ratio 1.53), and wheezing during work (odds ratio 3.33).

Preadmission antipyretics in Reye's syndrome.

The parents of 106 children who had had Reye's syndrome and those of 185 comparison children who had febrile illnesses were interviewed in order to compare preadmission medication exposure rates in the two groups. Although comparable proportions of case and comparison patients had taken antipyretics in the three weeks before admission, a significant excess of cases (59% compared with 26% in the comparisons) had been given aspirin, whereas significantly more comparison children (49% compared with 25% in the cases) had taken paracetamol. There was an excess exposure to aspirin in children under 5 years of age; the excess observed in older patients just failed to reach significance. Separate analyses within Northern Ireland and England also showed a case-comparison difference. A significant correlation was shown between aspirin (but not paracetamol) exposure and the closeness with which cases conformed to the diagnostic criteria of Reye's syndrome, measured by an artibrary score. The many difficulties of conducting and interpreting the findings of an epidemiological risk factor study of an association between aspirin and Reye's syndrome are reviewed and emphasised. Inherent biases were present in this as in previous studies and it did not conform to the classical case-control design. Nevertheless the findings suggested that an association between Reye's syndrome and preadmission aspirin may exist in some children.

Intracranial pressure monitors: epidemiologic study of risk factors and infections: Aucoin PJ, Kotilainen HR, Gantz N, et al. Am J Med 80:369, 1986

Intracranial pressure monitors: epidemiologic study of risk factors and infections: Aucoin PJ, Kotilainen HR, Gantz N, et al. Am J Med 80:369, 1986

Indirect methods of assessing the effects of tobacco use in occupational studies.

For various reasons, data on smoking are frequently missing, or only partially available, in retrospective epidemiologic studies of occupational risk factors. In such situations, indirect methods may be used to evaluate the magnitude and direction of the potentially confounding effects of smoking. Such an evaluation can be made quantitatively or qualitatively. Here we describe both approaches. A specific problem relates to case-referent studies, where sampling variation in referent selection may limit the possibility of controlling for confounding by smoking, even when smoking data are available. We present data showing that estimates of risk from occupational exposures which are not controlled for smoking may be as accurate as estimates derived after controlling for smoking, when the number of referents is relatively small. The problem of interaction is also discussed. In the absence of smoking data, the investigator has no indication of how smoking and occupation jointly affect disease risk (eg, additively or multiplicatively). The multiplicative model is usually assumed. However, if exposure and smoking act independently (additively), rate ratios are diminished. In such situations, in the presence of negative confounding by smoking, rate ratios may actually even be less than one--also when exposure and disease are strongly related.

Intracranial pressure monitors. Epidemiologic study of risk factors and infections: Aucoin PJ, Kotilainen HR, Gantz NM, et al Am J Med 80:369–376 Mar 1986

Intracranial pressure monitors. Epidemiologic study of risk factors and infections: Aucoin PJ, Kotilainen HR, Gantz NM, et al Am J Med 80:369–376 Mar 1986

Intracranial pressure monitors. Epidemiologic study of risk factors and infections

An increase in the number of cases of gram-negative ventriculomeningitis in patients followed with intracranial pressure monitors when compared with patients with craniotomy alone was revealed by routine surveillance data. A study was undertaken at four area institutions to describe the infections, risk factors, and management. Two hundred fifty-five patients with diagnoses of intracerebral hemorrhage (n = 86), closed trauma (n = 66), open trauma (n = 21), tumor (n = 66), and miscellaneous other conditions were compared with their nonmonitored counterparts for type of intracranial pressure monitor used, use of drains, prophylactic antibiotics, and steroids, and remote presence of infection. The presence of intracranial pressure monitor with craniotomy was associated with an 11 percent infection rate whereas craniotomy alone demonstrated a 6 percent rate. Of the intracranial pressure monitors used, the subarachnoid screw was associated with the lowest infection rate (7.5 percent) followed by the subdural cup catheter (14.9 percent) and the ventriculostomy catheter (21.9 percent). Regardless of the monitor used, infection was twice as likely to develop in patients with open trauma or hemorrhage. The use of bacitracin flush solutions for maintenance of lumen patency was more often associated with infections. Use of prophylactic antibiotics did not significantly influence outcome.

The influence of genetics and household environment upon the variability of normal blood pressure: the Montreal Adoption Survey.

The Montreal Adoption Survey was conducted as a cross-sectional epidemiologic study of cardiovascular risk factors in French Canadian families. Analysis included blood pressure readings of 756 adopted and 445 natural children as well as 1176 parents. A genetic model was applied to the analysis of our data. Interindividual variability of blood pressure was studied and observed correlatives of systolic and diastolic pressure of parental and non parental subjects were calculated. Based on the maximum likelihood estimates presented in the models the explanation of the parent offspring and the between sibs expected population correlatives for systolic blood pressure was the following: 61% was due to shared genes and 39% to environment shared by both parents and children. For diastolic blood pressure the explanation between parents and offspring was the following: 58% was due to shared genes and 42% due to shared environment across generation. The explanation between sibs was estimated to be the following: 33% due to generation, 24% to shared environment across generation and 43% to shared environment within generation.

Correcting for the Effect of Misclassification Bias in a Case-Control Study Using Data from Two Different Questionnaires

In an epidemiological study of risk factors in breast cancer, data are available on confirmed cases from a diagnostic clinic and on controls from a screening clinic that sampled the general population. Relative risk estimation is complicated by differences in the interviewing environment and in the wording and order of questions. This paper describes a statistical method based on likelihood theory, which makes use of data on women who have attended both clinics, and thence estimates clinic biases for each risk factor and produces revised conservative confidence intervals for relative risk.

Sex Differences in the Decline of Pulmonary Function with Age

As part of and as an adjunct to a longterm genetic and epidemiologic study of risk factors for chronic obstructive lung disease conducted at the Johns Hopkins Medical Institutions, we have been interested in examining the patterns of pulmonary function in different groups. In a study previously published,1 important male-female differences were noted in the pattern of pulmonary function observed in young smokers that led us to further examination of the pattern of change in pulmonary function in men and women under observation in the longterm genetic epidemiologic study.

The health impact of geochemical alterations associated with coal resource development in midwestern U.S.A.

It is projected that over the next 5 years surface coal mining in the United States will increase drastically. Because coal is a dirty fuel, mining and other geochemical changes in the environment may lead to increased health hazards. An epidemiologic study of possible risk factors associated with these geochemical alterations is presented. Mortality data and water quality data are analyzed and presented in the form of computer generated maps. A predictive model for use by the Environmental Protection Agency pertaining to the identification and control of pollutants is discussed.