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PubMed1991

The supply and demand dynamics of sexual behavior: implications for heterosexual HIV epidemics.

This article investigates the supply and demand dynamics of sexual behavior in a simple epidemiological model of heterosexual transmission of human immunodeficiency virus (HIV). The supply and demand dynamics of sexual behavior are modeled by specifying implicit sexual behavior change (ISBC) mechanisms. These mechanisms specify how males and females modify their rates of sex partner change in response to changes in the availability of the opposite sex. During an epidemic, the availability of both sexes will change owing to recruitment and mortality; consequently, implicit sexual behavior changes will be induced. These behavior changes will be independent of any explicit sexual behavioral changes that may occur as a result of intervention strategies. We investigate four different ISBC mechanisms: the two extremes of the continuum of possible mechanisms (where only one sex changes behavior), as well as two intermediate possibilities (where both sexes change behavior). The results show that the epidemiological effects of these ISBC mechanisms depend upon the transmission speed of the virus. If HIV transmission is slow, the epidemiological effects of the four ISBC mechanisms cannot be differentiated. If HIV transmission is fast, the four ISBC mechanisms differ considerably in the degree to which they modify the gender-specific rates of sex partner change, but the sexual behavioral changes occur too late to significantly decrease the cumulative number of infected persons. However, if HIV transmission is moderately fast, the four different ISBC mechanisms produce significantly different epidemics. The differences between the epidemics, produced by the four ISBC mechanisms, are magnified as the degree of asymmetry between the heterosexual transmission efficiencies increases. We discuss the implications of our results for both the future number of AIDS cases that will be observed in the "real world" and the number of AIDS cases that will be predicted from mathematical models. We also discuss the implications for studies that evaluate the causation of sexual behavior changes.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Aspects of confounding and effect modification in the assessment of occupational cancer risk.

In occupational health epidemiology, the confounding effects of general risk factors such as smoking and alcohol abuse with regard to cancer and other disorders seem to be rather limited. It is desirable to control such risk factors whenever possible, however, but risk ratios of about two or more can rarely be explained by suggesting uncontrolled confounding. However, various general risk factors might modify the effect of an industrial exposure, a phenomenon that sometimes tends to confuse the discussion of etiologic relationships between exposure and outcome.

Epidemiologic Methods↗
PubMed1994

The use of oral fluid for hepatitis C antibody screening.

OBJECTIVES: To assess the efficacy of oral fluid antibody testing for the detection of hepatitis C. METHODS: Paired serum and oral fluid collections were obtained from 216 subjects. A modification of the serum HCV ELISA assay was developed to improve test accuracy for an oral fluid substrate. Sensitivity was determined in 109 HCV serum ELISA-positive patients and specificity in 107 HCV serum ELISA-negative patients. RESULTS: Overall sensitivity of oral fluid collection and testing was 98.2%; specificity was 99.1%. These parameters did not seem to be altered by presence of concurrent hepatitis B infection, inflammatory state of the liver, or other factors. CONCLUSIONS: Oral fluid collection and HCV antibody testing by the modified ELISA method seems to be an effective and efficient alternatives to venipuncture and serum HCV antibody testing. Their use may facilitate epidemiological surveys and evaluation of individual patients when blood collection is not feasible.

Adult↗
PubMed1995

Fundamentals and possibilities of classification of occupational substances as developmental toxicants.

It is now widely accepted that describing and labeling of chemicals as developmental toxicants on a purely qualitative basis does not make sense. Agents possessing the potential to induce reproductive or developmental toxicity present a risk of human harm only under certain conditions. This critical fact cannot be properly communicated with a simple designation as "positive" or "negative". Rather, a number of parameters that deal with dose or concentration, frequency, duration and route of exposure must also be conveyed. Unsubstantiated blacklisting is equally counterproductive for preventive medicine as downplaying of the toxicity of chemicals. Gender-based restrictions on exposure at workplaces of women of child-bearing age are neither socially acceptable nor scientifically justifiable. Therefore, the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area published in 1983 a quantitatively based classification concept, which became effective in 1985 and was modified in the following years. The present contribution summarizes what is required for an integrated judgment on the relevance of laboratory and epidemiological data for predicting the potential risk associated with exposure at workplaces to occupational chemicals. Methyl mercury, carbon disulfide, dimethylformamide, ethanol, toluene, N,N-dimethyl acetamide, nitrous oxide, methanol, ethyl benzene, and phosphorus pentoxide will be described as examples of classified substances.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

The role of epidemiology in prevention of hypertension in Israel.

High blood pressure may be the most important modifiable determinant of severe morbidity and mortality in the adult population in Israel. Because hypertension control can effect a reduction in this morbidity and mortality, programs of secondary--and subsequently primary--prevention can have a far-reaching impact on the state of health in the nation. The primary care delivery system in Israel is structurally well suited to centrally directed initiatives. Major hypertension control programs are being introduced in Israel. The General Federation of Labour Sick Fund (Kupat Holim)--the nation's chief provider of primary care--has recently undertaken a wide-scale initiative for detection and treatment of high blood pressure in its neighborhood primary care clinics. A policy decision has thus been made on a national level; resources for intervention have been made available and activities initiated. The issue in need of resolution, the authors believe, is that of the integration of rigorous epidemiologic methodology into the planning and execution of the programs, particularly in program evaluation and resultant program modification. The authors outline selected epidemiologic characteristics of hypertension in Israel, emphasizing the major role that elevated blood pressure plays as a determinant of mortality; the present status of hypertension control; current programs for control; and the role of epidemiology in preventive programs.

Adult↗
PubMed1986

Interaction between tobacco smoking and occupational exposures in the causation of lung cancer.

The nature of the interaction between smoking and occupational exposure is controversial, in part because of lack of agreement on the definition of interaction and in part because of the scarcity of adequate epidemiologic data. Occupational investigators have assessed interaction primarily as a departure from an additive rather than from a multiplicative model of relative risks (or rate ratios). To determine whether smoking modifies the effect of occupational lung carcinogens, the literature was reviewed for the only four established occupational lung carcinogens for which there are data on smoking: radon daughters, asbestos, arsenic, and chloromethyl ethers. Where possible, departure was assessed from both an additive (synergism) and a multiplicative model (effect modification). Only nine studies were considered to have sufficient sample size and to provide sufficient information on tobacco use and occupational exposure to evaluate interaction. The existing data were contradictory for three of the agents studied: asbestos, radon daughters, and arsenic. Inconclusive or contradictory findings may result from small sample size or lack of comparability of the level of occupational or tobacco exposure. It is noteworthy that, for these four agents, whenever smoking did modify the effect of occupational exposure, the lung cancer rate ratio was greater for nonsmokers (compared to nonexposed nonsmokers) than smokers (compared to nonexposed smokers). However, with the exception of chloromethyl ethers, absolute lung cancer rates were higher for smokers than nonsmokers, regardless of occupational exposure.

Arsenic Poisoning↗
PubMed2004

Applying new biotechnologies to the study of occupational cancer--a workshop summary.

As high-throughput technologies in genomics, transcriptomics, and proteomics evolve, questions arise about their use in the assessment of occupational cancers. To address these questions, the National Institute for Occupational Safety and Health, the National Cancer Institute, the National Institute of Environmental Health Sciences, and the American Chemistry Council sponsored a workshop 8-9 May 2002 in Washington, DC. The workshop brought together 80 international specialists whose objective was to identify the means for best exploiting new technologies to enhance methods for laboratory investigation, epidemiologic evaluation, risk assessment, and prevention of occupational cancer. The workshop focused on identifying and interpreting markers for early biologic effect and inherited modifiers of risk.

Biomarkers↗
PubMed1992

[Cardiac and humoral mechanisms of the preventive effect of physical activity on cardiovascular diseases].

Many recent studies on the effects of regular exercise on the heart, coronary arteries and the balance between haemostasis and fibrinolysis suggest several mechanisms that are able to explain the epidemiologically well-documented association of habitual physical activity with a reduced risk of cardiovascular disease. Based on a review of current evidence, it is proposed that i) the haemodynamic adaptation of an aerobically-trained heart is an important cardioprotective mechanism, ii) the importance of exercise-induced effects on the coronary vessels may currently be somewhat underestimated, and iii) the importance of training-related changes in the haemostatic-fibrinolytic balance is equivocal at present, since the relative intensity of exercise seems to be a modifying factor that has not been taken into account appropriately so far. Further biomedical research into the cardiac and humoral effect of physical training is, thus, needed to corroborate the recent epidemiological observation that moderate-intensity exercise is just as--or even more--cardioprotective than high-intensity sports activity.

Cardiomegaly↗
PubMed2005

The evaluation of rectal bleeding in adults. A cost-effectiveness analysis comparing four diagnostic strategies.

BACKGROUND: Though primary care patients commonly present with rectal bleeding, the optimal evaluation strategy remains unknown. OBJECTIVE: To compare the cost-effectiveness of four diagnostic strategies in the evaluation of rectal bleeding. DESIGN: Cost-effectiveness analysis using a Markov decision model. DATA SOURCES: Systematic review of the literature, Medicare reimbursement data, Surveillance, Epidemiology, and End Results (SEER) Cancer Registry. TARGET POPULATION: Patients over age 40 with otherwise asymptomatic rectal bleeding. TIME HORIZON: The patient's lifetime. PERSPECTIVE: Modified societal perspective. INTERVENTIONS: Watchful waiting, flexible sigmoidoscopy, flexible sigmoidoscopy followed by air contrast barium enema (FS+ACBE), and colonoscopy. OUTCOME MEASURES: Incremental cost-effectiveness ratio. RESULTS OF BASE-CASE ANALYSIS: The incremental cost-effectiveness ratio for colonoscopy compared with flexible sigmoidoscopy was 5,480 dollars per quality-adjusted year of life saved (QALY). Watchful waiting and FS+ACBE were more expensive and less effective than colonoscopy. RESULTS OF SENSITIVITY ANALYSES: The cost of colonoscopy was reduced to 1,686 dollars per QALY when age at entry was changed to 45. Watchful waiting became the least expensive strategy when community procedure charges replaced Medicare costs, when age at entry was maximized to 80, or when the prevalence of polyps was lowered to 7%, but the remaining strategies provided greater life expectancy at relatively low cost. The strategy of FS+ACBE remained more expensive and less effective in all analyses. In the remaining sensitivity analyses, the incremental cost-effectiveness of colonoscopy compared with flexible sigmoidoscopy never rose above 34,000 dollars. CONCLUSIONS: Colonoscopy is a cost-effective method to evaluate otherwise asymptomatic rectal bleeding, with a low cost per QALY compared to other strategies.

Adult↗
PubMed1991

Ambulatory blood pressure monitoring: assessing the diurnal variation of blood pressure.

The purposes of this paper are to examine the effects of activity, situation of measurement, mood, and occupation on the daily variation of blood pressure and to discuss the potential utility of ambulatory blood pressure monitoring in physical anthropological studies. The subjects of the blood pressure variability study are 125 men who were referred to the Hypertension Center at New York Hospital--Cornell Medical Center for evaluation of hypertension. There were 1,386 blood pressure measurements from these subjects available for study, which were taken using noninvasive ambulatory blood pressure monitoring techniques. Pressures were transformed to z scores using the subject's daily mean pressure and standard deviation to assess the relative elevation during the experience of the various factors. The results show that activity and mood are the most significant sources of blood pressure variation (P less than .005) and are additive. Occupation, which may be an indicator of social class in this population, also modified the mood effects. Because ambulatory blood pressure monitors obtain many readings over a day under a variety of circumstances, their use can improve epidemiological and human biological studies of the inheritance and variability of blood pressure. Ambulatory blood pressure monitoring is an important new tool in the study of human biological variation.

Affect↗
PubMed2005

Responsiveness of generic health-related quality of life measures in stroke.

OBJECTIVE: To compare five preference-based generic measures of health-related quality of life (HRQOL) in terms of change scores, correlations among change scores, responsiveness, and quality adjusted life-years (QALYs) gained. DESIGN: Observational longitudinal cohort study where clinical measures and self-assessed HRQOL measures were administered to stroke patients at baseline and at 6 months. Patients were categorized as 'stable', 'some improvement' and 'large improvement' using the Barthel Index, Modified Rankin Scale (MRS), and Center for Epidemiologic Studies Depression Scale (CES-D). For each group, paired t-tests and variants of effect size were used to compare the responsiveness of preference-based HRQOL summary scores, including the EQ-5D VAS and index-based score, SF-6D, and Health Utilities Index (HUI) Mark 2 (HUI2) and Mark 3 (HUI3) overall utility scores. RESULTS: Ninety-eight of 124 (79%) patients completed the 6-month follow-up. Change scores of the EQ-Index, HUI2, and HUI3 were strongly correlated with changes in the Barthel Index and MRS, while the EQ-5D VAS had higher correlation with CES-D change scores than the other measures. The SF-6D, HUI3, and EQ-Index were generally more responsive than the HUI2 and EQ-5D Visual analogue scale (EQ-VAS). QALY estimates based on the EQ-5D index and HUI3 were twice as large as estimates based on the SF-6D and HUI2. CONCLUSIONS: The results of this study may assist in informing the selection of a preference-based generic HRQOL measure, although choice will also depend on study goals and context. We would caution against the generalization of the study results on responsiveness to conditions when more subtle change is expected.

Alberta↗
PubMed1985

The antisocial personality: a review.

Definition, understanding, and treatment of antisocial personality disorder continue to present difficulties, but there have been several encouraging developments. Recently published data on antisocial syndromes from several different disciplines have been strikingly consistent and have raised hopes for an integrated understanding of the disorder. In addition, many of the sources of antisocial symptoms have been identified, and certain highly structured therapeutic programs have been effective in modifying antisocial behavior. The paper reviews the latest issues related to diagnosis, symptom presentation, and treatment, as well as pathologic, sociologic, and epidemiologic aspects of the disorder.

Adolescent↗
PubMed2005

BRCA1 in hormonal carcinogenesis: basic and clinical research.

The breast and ovarian cancer susceptibility gene-1 (BRCA1) located on chromosome 17q21 encodes a tumor suppressor gene that functions, in part, as a caretaker gene in preserving chromosomal stability. The observation that most BRCA1 mutant breast cancers are hormone receptor negative has led some to question whether hormonal factors contribute to the etiology of BRCA1-mutant breast cancers. Nevertheless, the caretaker function of BRCA1 is a generic one and does not explain why BRCA1 mutations confer a specific risk for tumor types that are hormone-responsive or that hormonal factors contribute to the etiology, including those of the breast, uterus, cervix, and prostate. An accumulating body of research indicates that in addition to its well-established roles in regulation of the DNA damage response, the BRCA1 protein interacts with steroid hormone receptors (estrogen receptor (ER-alpha) and androgen receptor (AR)) and regulates their activity, inhibiting ER-alpha activity and stimulating AR activity. The ability of BRCA1 to regulate steroid hormone action is consistent with clinical-epidemiological research suggesting that: (i) hormonal factors contribute to breast cancer risk in BRCA1 mutation carriers; and (ii) the spectrum of risk-modifying effects of hormonal factors in BRCA1 carriers is not identical to that observed in the general population. These data suggest a model for BRCA1 carcinogenesis in which genomic instability leads to the initiation of cancerous cell clones, while loss of normal restraint on hormonal stimulation of mammary epithelial cell proliferation allows amplification of these pre-existing clones. Further research will be required to substantiate this hypothesis.

Breast Neoplasms↗
PubMed1999

Antimutagenic/antioxidant activity of green tea components and related compounds.

The ability of green tea components and other antioxidant compounds to function as antimutagens/antioxidants has been well established, and their role in cancer prevention is supported by numerous epidemiological studies. We have utilized modified Ames tests, superoxide scavenging assays, and assays for protection against DNA scissions to compare and contrast the protective effects of various teas and commercial and laboratory-isolated tea components to those produced by compounds such as resveratrol, selenium, curcumin, vitamins C and E, quercetin dihydrate, sulforaphane, ellagic acid dihydrate, glutathione reduced, trolox, butylated hydroxanisole (BHA), butylated hydroxytoluene (BHT), and N-acetyl-L-cysteine (NAC). In Ames tests, employing hydrogen peroxide as a mutagen, epigallocatechin gallate (EGCG) produced the highest level of protection of all antioxidants tested. Measurement of protection against DNA scissions produced results that again showed that EGCG produced the strongest protective effects. In scavenging assays using a xanthine-xanthine oxidase (enzymatic system), epicatechin gallate (ECG) showed the highest scavenging potential. In a nonenzymatic (phenazine methosulfate-NADH) oxidizing system, EGCG once again showed the strongest effects. The implications of these and similar results are discussed in relation to cancer prevention and prevention of drug/antibiotic resistance.

Antimutagenic Agents↗
PubMedDate not supplied

Occupational (and non-occupational) risk factors for musculoskeletal disorders.

BACKGROUND: Musculoskeletal disorders are an important cause of disability and absence from work in industrialized countries. A number of studies reported the importance of occupational, personal and psycho-social factors in the aetiology of these work-related disorders. OBJECTIVES AND METHODS: To stress the complex relationships existing between risk factors, reporting findings from reviews and original studies regarding two of the most significant musculoskeletal disorders: carpal tunnel syndrome (CTS) and low back pain (LBP). CONCLUSIONS: More detailed epidemiological studies are needed to explore the interactions between risk (and protective) factors, since these can play the role of determinants, confounders or effect modifiers.

Carpal Tunnel Syndrome↗
PubMed1993

The treatment of overuse injury syndrome.

The emphasis on performance injury has shifted from epidemiology to prevention. Rest treatment, modified or radical, followed by rehabilitation, remains the cornerstone of treatment. The basic features, details of management, and side effects of these treatment phases are discussed at length, followed by a detailed description of the author's experience with 176 musicians seen for overuse injury syndrome. Forty-one patients were not prescribed rest treatment, refused rest treatment, or quit rest treatment early; 45 patients were prescribed a modified rest treatment program, of whom 87% were cured of symptoms; and 90 patients were prescribed radical rest treatment, with a final success rate of 87% also.

Arm Injuries↗
PubMed2003

Smoking, gender and rheumatoid arthritis-epidemiological clues to etiology. Results from the behavioral risk factor surveillance system.

OBJECTIVES: This study was undertaken to confirm and extend our earlier observation that gender is a biological effect modifier of smoking-rheumatoid arthritis (RA) relationship in a diverse national survey sample in the United States. METHODS: Smoking history of 644 cases of RA and 1509 geographically matched general population controls were compared using weighted logistic regression. RESULTS: There were 644 respondents with RA (cases) and 1509 geographically matched controls. Cases were significantly younger, less educated, more likely to be single and female than controls. Among cases 57% were smokers while among controls 49% smoked. Among women, after adjusting for age, hysterectomy had an age adjusted odds ratio 1.45, (95% CI 0.99-2.10) and menopause an adjusted odds ratio 1.18 (95% CI 0.99-2.10) were associated with smoking. In univariable analysis ever-smoking was associated with increased risk of RA (odds ratio 1.34, 95% CI 1.0-1.81). Among the strata of smokers, there was an increasing gradient of risk with increasing exposure to smoking (P = 0.041). In separate multivariable models, smoking increased the risk in men (odds ratio 2.29, 95% CI 1.35-3.90) while in women the risk was not elevated (odds ratio 0.98, 95% CI 0.67-1.42). After adjusting for the statistically significant interaction both female gender (odds ratio 2.30, 95% CI 1.39-3.83) and having ever smoked (odds ratio 2.31, 95% CI 1.36-3.94) emerged as significant risk factors for RA. CONCLUSIONS: Gender interacts with smoking in by an unknown mechanism to lead to differential risk of RA.

Adult↗
PubMed1997

Reanalysis of the occurrence of back pain among construction workers: modelling for the interdependent effects of heavy physical work, earlier back accidents, and aging.

OBJECTIVES: To re-examine the relation between heavy physical work and the occurrence of sciatic pain among construction workers reported previously to be absent in an epidemiological study. METHODS-Poisson log linear regression was used to model for the frequency of sciatic pain among concrete reinforcement workers and maintenance house painters with adjustment for the interactive effects of earlier back accidents and aging that modified the relation. RESULTS: Concrete reinforcement work not only had a direct effect on the frequency of sciatic pain, but it also contributed significantly to the risk indirectly through earlier back accidents. The risk of sciatic pain increased from age 25 to 54 in a different manner for a worker depending on his occupational group and record of back accidents. CONCLUSIONS: Epidemiological studies on low back pain need to be analysed with sound methodology. This is important in view of future meta-analyses that will be performed for the purpose of providing guidelines on the prevention of back disorders in heavy physical work.

Accidents, Occupational↗