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Results for “Effect Modifier, Epidemiologic”

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At least 739 records · Page 41Linked to original sources
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↗
PubMed1996

[Causal inference in medicine--a historical view in epidemiology].

Changes of causal inference concepts in medicine, especially those having to do with chronic diseases, were reviewed. The review is divided into five sections. First, several articles on the increased academic acceptance of observational research are cited. Second, the definitions of confounder and effect modifier concepts are explained. Third, the debate over the so-called "criteria for causal inference" was discussed. Many articles have pointed out various problems related to the lack of logical bases for standard criteria, however, such criteria continue to be misapplied in Japan. Fourth, the Popperian and verificationist concepts of causal inference are summarized. Lastly, a recent controversy on meta-analysis is explained. Causal inference plays an important role in epidemiologic theory and medicine. However, because this concept has not been well-introduced in Japan, there has been much misuse of the concept, especially when used for conventional criteria.

Causality↗
PubMed2000

Dietary marine fatty acids (fish oil) for asthma.

BACKGROUND: Epidemiological studies suggest that a diet high in marine fatty acids (fish oil) may have beneficial effects on inflammatory conditions such as rheumatoid arthritis and possibly asthma. OBJECTIVES: 1. To determine the effect of marine n-3 fatty acid (fish oil) supplementation in asthma. 2. To determine the effect of a diet high in fish oil in asthma. SEARCH STRATEGY: The Cochrane Airways Review Group register was search using the terms: marine fatty acids OR diet OR nutrition OR fish oil OR eicosapentaenoic acid OR EPA. Bibliographies of retrieved trials were searched and fish oil manufacturers contacted. SELECTION CRITERIA: Randomised controlled trials in patients with asthma more than two years of age were included. The study duration had to be in excess of 4 weeks. Double blind trials were preferred, but single-blind and open trials were also reviewed for possible inclusion. Three reviewers read each paper, blind to its identity. Decisions concerning inclusion were made by simple majority. Quality assessment was performed by all three reviewers independently. DATA COLLECTION AND ANALYSIS: The only comparison possible was between marine n-3 fatty acid supplementation and placebo. There were insufficient trials to examine dietary manipulation alone. MAIN RESULTS: Eight randomised controlled trials conducted between 1986 and 1998 satisfied the inclusion criteria. Six were of parallel design and two were cross-over studies. Seven compared fish oil with placebo whilst one compared high dose vs low dose marine n-3 fatty acid supplementation. None of the included studies reported asthma exacerbations, health status or hospital admissions. There was no consistent effect on any of the analyzable outcomes: FEV1, peak flow rate, asthma symptoms, asthma medication use or bronchial hyper reactivity. The single study performed in children also combined dietary manipulation with fish oil supplementation and showed improved peak flow and reduced asthma medication use. There were no adverse events associated with fish oil supplements. REVIEWER'S CONCLUSIONS: There is little evidence to recommend that people with asthma supplement or modify their dietary intake of marine n-3 fatty acids (fish oil) in order to improve their asthma control. Equally, there is no evidence that they are at risk if they do so.

Adult↗
PubMed2006

Use of hormonal therapy in men with metastatic prostate cancer.

PURPOSE: Bilateral orchiectomy or luteinizing hormone releasing hormone agonists represent the standard of care for metastatic prostate cancer. In this population based study we assessed the use rates of these therapies in men who died of prostate cancer. MATERIAL AND METHODS: A total of 9,110 men 65 years or older who died of prostate cancer in 1991 to 2000 were identified through the population based Surveillance, Epidemiology and End Results, and Medicare linked database to determine hormonal therapy use rates. A modified Poisson regression model was used to estimate the adjusted effects of various factors associated with hormone use. RESULTS: Approximately 38% of black and 25% of white men did not receive hormonal therapy before dying of prostate cancer. After adjusting for cancer status at diagnosis and other potential confounding factors black race and residence in low income areas were associated with lower hormonal therapy use (relative risk 0.73, 95% CI 0.67 to 0.80 and 0.91, 95% CI 0.85 to 0.98, respectively). Hormonal therapy use was most comprehensive in the Northeast. CONCLUSIONS: A substantial number of men who die as a consequence of prostate cancer never receive hormonal therapy. The use of hormonal therapy varies significantly. Further studies are warranted to determine factors that may be associated with the incomplete use of hormonal therapy for metastatic prostate cancer.

Aged↗
PubMed2006

Drug resistance in tuberculosis--a reinfection model.

There is increasing recognition that reinfection is an important component of TB transmission. Moreover, it has been shown that partial immunity has significant epidemiological consequences, particularly in what concerns disease prevalence and effectiveness of control measures. We address the problem of drug resistance as a competition between two types of strains of Mycobacterium tuberculosis: those that are sensitive to anti-tuberculosis drugs and those that are resistant. Our objective is to characterise the role of reinfection in the transmission of drug-resistant tuberculosis. The long-term behaviour of our model reflects how reinfection modifies the conditions for coexistence of sensitive and resistant strains. This sets the scene for discussing how strain prevalence is affected by different control strategies. It is shown that intervention effectiveness is highly sensitive to the baseline epidemiological setting.

Antitubercular Agents↗
PubMed1985

Hospital usage of parenteral antimicrobial agents: a gradated utilization review and cost containment program.

Forty percent to 60% of antimicrobial agents administered in hospitals without effective antimicrobial review and control programs are not needed. Excessive use of antimicrobial agents in the hospital promotes colonization of patients with resistant organisms, needlessly exposes them to the risk of an adverse drug reaction, and increases the cost of care. A gradated antimicrobial utilization review program is presented that determines hospital usage, develops guidelines for appropriate cost-effective drug administration, provides several options for implementation, and monitors outcome so that measures can be modified for specific situations. The techniques used are basic epidemiologic measures currently used to assess hospital infections.

Anti-Bacterial Agents↗
PubMed2005

Selected DNA repair polymorphisms and gastric cancer in Poland.

Impaired DNA repair capacity may adversely affect cancer risk, particularly in subjects exposed to DNA damaging carcinogens, as found in tobacco smoke, or among subjects deficient for protective factors, as found in fruits and vegetables. We studied tobacco use, fruit and vegetable intake, and common non-synonymous single nucleotide polymorphisms in four DNA repair genes in relation to gastric cancer risk, in a population-based, case-control study of 281 incident gastric cancer cases and 390 controls, in Warsaw, Poland. Multivariate logistic regression analysis was performed to calculate odds ratios (OR) and 95% confidence intervals (CI). Increased risks of gastric cancer were found for smokers (OR=3.1, CI=1.9-5.1 for pack-years>or=40 versus never smokers) and subjects with low fruit intake (OR=2.2, CI=1.3-3.6 for 1st versus 4th quartile); risk associated with vegetable intake was not statistically significant. Allele frequencies among the controls were consistent with those previously reported for the 5 polymorphisms studied: XRCC1-Arg399Gln, XPD-Lys751Gln, MGMT-Ile143Val, Leu84Phe, and XRCC3-Thr241Met. None of the studied polymorphisms were independently associated with gastric cancer risk. Smoking-associated risks, however, were greatest for carriers of the XRCC1-399 ArgArg genotype (Pinteraction=0.004). Risks associated with low intake of fruits or vegetables tended to be modified by selected polymorphisms in XRCC1, XPD and MGMT (Pinteraction=0.1-0.2). Risk modification was not found for the other repair polymorphisms. Selected DNA repair polymorphisms did not have independent effects on gastric cancer risk; however, they may modify smoking- and probably diet-related risks for this disease. These results need replication in larger epidemiological studies of gastric cancer.

Adult↗
PubMed2006

Diet synergies and mortality--a population-based case-control study of 32,462 Hong Kong Chinese older adults.

BACKGROUND: Food and drink are not consumed in isolation and can have complimentary effects enhancing or blocking the overall uptake of nutrients. We investigated how combinations of foods, drinks, and smoking affected mortality. Method Adjusted logistic regression was used to assess the joint effect of healthy foods, less healthy foods, smoking, and alcohol use on mortality in a case-control study of all Chinese adults aged 60 or over who died in 1998; 21,494 dead cases (81% of all registered deaths) and 10,968 live controls were included. RESULTS: There was a significant trend of increasing all-cause mortality risk with decreasing healthy food consumption (P < 0.001), and the increase in risk was significantly steeper for people with high intakes of less healthy food (P for interaction <0.001). There was a steeper risk from increasing less healthy food intake in ever-smokers and people not drinking tea regularly (P < 0.001), while the J-shaped relationship between alcohol and mortality differed in shape with level of less healthy food intake. CONCLUSION: Intake of some dietary items may modify the effect of others. An analysis framework explicitly recognizing complementary and potentially synergistic effects of food, drinks, and smoking could enhance our understanding of dietary epidemiology.

Aged↗
PubMed1991

Evaluation of the modified Baermann's method in the laboratory diagnosis of Strongyloides stercoralis.

This study compares the modified Baermann's method with the formol-ether concentration and the direct/saline techniques in the diagnosis of Strongyloides stercoralis larvae in stool specimens. This study was conducted at Wonji-Shewa Sugar Estate located at about 110 kms. south east of Addis Abeba. Of the 718 randomly selected and examined stool specimens, 125 were found positive for Strongyloides stercoralis. Of these 98% were recovered by the modified Baermann's method, 23% by the formol-ether, and 22% by the direct saline techniques. The rate of recovery by the modified Baermann's method was significantly different (p less than 0.001) compared with those of the direct and the formol-ether concentration techniques. There was no difference (p greater than 0.1) between the direct saline and the formol-ether methods. The modified Baermann's method accounted for over 60% of the total positive findings. Furthermore, the sensitivity of the method excelled the other two techniques by four fold. Thus, the modified Baermann's method by the Merck and Sharp Dohme Company is effective, cheap and simple to use and hence recommended for routine use and epidemiological surveys.

Adolescent↗
PubMed2001

Higher risk of pre-eclampsia after change of partner. An effect of longer interpregnancy intervals?

Epidemiologic studies have shown that pre-eclampsia is mainly a disease of first pregnancy, possibly associated with primipaternity. The interpregnancy interval, which is strongly associated with change of partner, has received little attention. In this study, based on Danish hospital records, we evaluated whether the interpregnancy interval may confound or modify the paternal effect on pre-eclampsia. We studied the outcome of the second birth in a cohort of Danish women with pre-eclampsia in the previous birth (8,401 women) and in all women with pre-eclampsia in second (but not first) birth together with a sample of women with two births (26,596 women). A long interpregnancy interval was associated with a higher risk of pre-eclampsia in women with no previous pre-eclampsia when the father was the same. We estimated the risk of pre-eclampsia in second birth according to paternal change in different models. Although partner change was associated with an increased risk of pre-eclampsia in women with no history of pre-eclampsia, this effect disappeared after adjustment for the interpregnancy interval. We saw, however, different results when we stratified on the length of the interval. Our results indicate that the interval between births should be taken into consideration when studying the effect of changing partner on pre-eclampsia.

Adult↗
PubMed2025

Entertainment activities and the risk of multiple sclerosis: A Mendelian randomization analysis.

Modifying environmental and lifestyle factors may have the potential to prevent and ameliorate multiple sclerosis. Further elucidating the etiology of multiple sclerosis and proposing actionable prevention measures are of significant importance, but establishing causality in epidemiological data can be challenging. This study employed a two-sample Mendelian randomization analysis to evaluate the causal effect of entertainment activity factors on the risk of multiple sclerosis. Publicly accessible summary statistics derived from genome-wide association studies were utilized to assess 14 modifiable forms of entertainment activities. The inverse variance weighted random effects method was used as the primary analytical approach to estimate causal effects. Additionally, MR-Egger, weighted median, and weighted mode methods were applied to assess robustness. Systematic sensitivity analyses and heterogeneity tests were conducted to verify the reliability of our findings. We found that spending time outdoors in the summer may prevent the development of multiple sclerosis (odds ratio = 0.995; 95% confidence interval 0.991-0.999; P&#x2005;=&#x2005;.010). In contrast, the other entertainment activities studied showed no significant causal relationship with multiple sclerosis. Our results suggest that spending time outdoors in the summer may protect against the development of multiple sclerosis, providing implications for preventive measures against the disease.

Humans↗
PubMed1998

Assessing the benefits of lipid-lowering therapy.

In recent years, a substantial body of evidence has emerged to support the use of lipid-lowering therapy in the prevention of coronary artery disease, and many physician groups have endorsed the management of dyslipidemia in at-risk patients. An important consideration in such endorsements has been the issue of the safety of lipid intervention; many early primary- and secondary-prevention studies reported either no reduction in all-cause mortality rates or an increase in non-coronary artery disease mortality rates in treated patients. These observations raised serious concerns about the safety of such therapy. However, 2 landmark studies, the Scandinavian Simvastatin Survival Study (4S) and the West of Scotland Coronary Prevention Study (WOSCOPS), have contributed greatly to alleviating these concerns. In this article, a review of the epidemiologic evidence supporting the use of lipid modification will be presented, including important trials and meta-analyses, and the cost-effectiveness of lipid-modifying treatment will be discussed.

Cause of Death↗
PubMed2004

A modified poisson regression approach to prospective studies with binary data.

Relative risk is usually the parameter of interest in epidemiologic and medical studies. In this paper, the author proposes a modified Poisson regression approach (i.e., Poisson regression with a robust error variance) to estimate this effect measure directly. A simple 2-by-2 table is used to justify the validity of this approach. Results from a limited simulation study indicate that this approach is very reliable even with total sample sizes as small as 100. The method is illustrated with two data sets.

Clinical Trials as Topic↗
PubMed1993

Cellular, molecular, and carcinogenic effects of radiation.

(1) The biologic effects of ionizing radiation at the cellular and molecular levels differ from those of many chemical agents. Radiation is a classic genotoxic agent. The important DNA lesion with respect to its cytotoxic and mutagenic effects appears to be the DNA double strand break, whereas chemotherapeutic alkylating agents induce primarily base damage from adduct formation and cross-linking. Radiation-induced mutations result primarily from large-scale structural changes in DNA as a result of mechanisms such as chromosomal deletions, rearrangements, and homologous recombination, rather than point mutation as generally observed with alkylating agents. Finally, radiation is highly cytotoxic; a significantly increased frequency of specific gene mutations is usually observed only following doses that produce significant cell killing. (2) Radiation may not be a very potent inducer of second malignant tumors, at least in most cases. This prediction is derived from the localized nature of the exposure during clinical radiotherapy, in which the dose to normal tissues is minimized, and from the fact that radiation tends to be cytotoxic rather than mutagenic. The very high doses employed in curative radiotherapy may thus kill potentially transformed cells in the field. An exception to this general prediction may be Hodgkin's disease, in which a relatively large volume of tissue is treated with lower total radiation doses. (3) We have a firm scientific basis on which to predict the carcinogenic effects of radiation at many tissue sites, owing to extensive quantitative epidemiologic data in human populations. Unlike for chemical agents, radiation can be easily detected, and the absorbed dose to critical tissues is precisely measured. Thus, we know about the sensitivity of many target tissues to radiation-induced cancer. (4) A number of factors can modify the carcinogenic effects of radiation. It is likely that important interactive effects will occur between radiation and chemotherapeutic alkylating agents, which may depend upon the timing and order of the treatments as well as the particular agent(s) employed. (5) Genetic predisposition to radiation-induced cancer may be a confounding factor in the prediction of its effects in any given individual.

Animals↗
PubMed1995

The contribution of epidemiology to the definition of health goals and targets for Australia.

Health goals and targets may be used to improve the efficiency of investment of resources for health care and the promotion of health the better to fulfil the values and expectations of society. Australia has been developing health goals and targets since 1985. The first step was the establishment of the Better Health Commission that year. Its proposals led to the states and territories undertaking concerted health promotion activities through the National Better Health Program. Subsequently the health-care system as a whole, through the 1993 Medicare agreement, endorsed the goals and targets approach. Epidemiology has played a major role in every step in this process. Initially it was used to establish health status baselines or to point to serious data deficits which stopped a baseline being set. It provided data about the burden and distribution of illness in the community. It was used critically to appraise evidence about aetiology and the fraction of illness attributable to modifiable risk factors and the effectiveness of interventions, and to provide estimates of potential years of life lost through illness and injury. This has contributed, along with economic analysis which is a critically important corollary, to the definition of health care priorities. Epidemiology, while being necessary for these developments, however, has not been sufficient. This 'insufficiency' has three elements. First, existing epidemiological knowledge and methods have been inadequately applied or the data have been missing, or distorted by inappropriate interpretation. Second, there are now goals and targets in health literacy, the health care system, and the environment where epidemiological methods (and hence data) are poorly developed or non-existent.(ABSTRACT TRUNCATED AT 250 WORDS)

Australia↗
PubMed1995

Studying the causes of kidney disease in humans: a review of methodologic obstacles and possible solutions.

Until recently, epidemiology has contributed little to the understanding of kidney disease etiology. In the past, the immediate need for therapy eclipsed the longer-term need to develop preventive strategies. As a result, kidney disease epidemiology lacked sufficient institutional and financial support. These difficulties are being progressively (albeit yet incompletely) resolved. Other obstacles pertained to research methods. The need for large cohort studies to investigate a relatively uncommon outcome can be overcome by the use of alternative study designs, such as nonconcurrent prospective studies or case control studies. Unfortunately, other methodologic obstacles remain. These include (1) lack of sensitive markers of early renal insufficiency for use in general populations, (2) variations in access to end-stage renal disease therapy, (3) uncertainty regarding cause-of-death certification in persons with kidney diseases, (4) ambiguous criteria for diagnosing specific renal diseases, (5) lack of independence between risk factor assessments and kidney disease definition, (6) inconsistent risk factor assessments, and (7) inadequate conceptual models for causation of kidney failure. We suggest a global framework, including (1) defining rigorous diagnostic criteria for renal diseases, (2) conducting etiologic studies of "all-cause" end-stage renal disease, (3) systematically collecting data on risk factors for renal injury, and (5) distinguishing between initiators and promoters of renal insufficiency and between proximate and distal risk factors. These suggestions aim to foster a multidisciplinary debate on etiologic research on renal diseases. Identification of modifiable risk factors may provide a basis for effective preventive interventions.

Epidemiologic Methods↗
PubMed2004

Determinants of F2-isoprostane biosynthesis and inhibition in man.

Several cardiovascular risk factors are characterized by the coexistence of low-grade inflammation, enhanced oxidative stress and lipid peroxidation. It has been hypothesized that F2-isoprostanes, a product of in vivo lipid peroxidation, may transduce the effects of metabolic and hemodynamic abnormalities into increased cardiovascular risk. Thus, the formation of these compounds, including urinary 8-iso-Prostaglandin (PG) F2alpha, has been investigated in clinical settings putatively associated with oxidant stress. Enhanced lipid peroxidation together with increased in vivo platelet activation have been found in association with the major cardiovascular risk factors. Thus, F2-isoprostanes may transduce the effects of oxidant stress associated with complex metabolic disorders into specialized forms of cellular activation. In particular, the low-grade inflammatory state characterizing metabolic disorders such as obesity, hypercholesterolemia, type 2 diabetes mellitus, and homozygous homocystinuria may be the primary trigger of thromboxane-dependent platelet activation mediated, at least in part, through enhanced lipid peroxidation. Moreover, oxidative stress may promote endothelial dysfunction through increased production of reactive oxygen species that inactivate nitric oxide. Accumulation and activation of leukocytes plays a key role in atherosclerosis and its complications. Interestingly, neutrophil adhesion induced by minimally modified low-density lipoproteins is mainly mediated by F2-isoprostanes. Although epidemiological studies suggest an inverse relationship between antioxidant vitamin intake and cardiovascular disease, several clinical trials have obtained conflicting results on the effects of vitamin E supplementation on the risk of cardiovascular events. On the other hand, the use of F2-isoprostane formation as a biochemical end-point for dose-finding studies of vitamin E supplementation has helped clarifying the unique features of its pharmacodynamic effects on lipid peroxidation. This information could be extremely valuable in the selection of the appropriate patient subgroups that may benefit from antioxidant interventions.

Antioxidants↗
PubMed2007

The 4G/4G PAI-1 genotype is associated with elevated plasma PAI-1 levels regardless of variables of the metabolic syndrome and smoking status. A population-based study in Spanish population.

Reported data about the effect of the 4G/5G PAI-1 polymorphism on plasma PAI-1 levels are controversial. This study was designed to determine the relative effect of the 4G/5G PAI-1 polymorphism on high plasma PAI-1 levels after adjustment for metabolic syndrome - related variables, and to test if this effect is modified by the smoking status. Six hundred and thirty one unrelated subjects (292 men; 35-74 years), from a cross-sectional population-based epidemiological survey in the province of Segovia (Spain) were studied. The higher frequency of high PAI-1 levels was found in 4G/4G subjects (5G/5G 19.4%, 4G/5G 21.6%, 4G/4G 33.7%, p = 0.003). A multiple regression model, adjusted for gender, age, BMI, waist circumference, triglycerides, HDL-cholesterol, HOMA IR and leptin, showed this adjOR: 4G/4G vs 5G/5G: 2.22, p = 0.008. When smoking status - 4G/5G PAI-1 interaction was included as an independent variable these results were not modified. Our results indicate that the 4G/4G PAI-1 genotype might be strongly associated with high PAI-1 levels regardless of metabolic syndrome-related variables and smoking status.

Adult↗