Epidemiological intervention studies

Epidemiological studies on the prevention of contact dermatitis in the work environment are needed to prove the effectiveness of preventive measures and interventions. Presently, epidemiological intervention studies that evaluate the relative impact of various measures to prevent contact dermatitis, have not been published. 

By adding ferrous sulfate to the cement, it is possible to prevent the development of allergic cement eczema. This was illustrated in an epidemiological intervention study from Denmark (Avnstorp 1992) and in reports from Finland and Sweden (Roto et al. 1996). 

Avnstorp C (1992) Cement eczema. An epidemiological intervention study. Acta Derm Venereol Suppl (Stockh) 179 5-22... 

Intervention studies. Intervention studies represent the experimental aspect of epidemiology. Intervention studies are prospective studies in which an exposure or exposures are assigned to people and subsequent outcomes observed. 

Many epidemiological studies have analyzed the correlations between different carotenoids and the various forms of cancer and a lot of conclusions converge toward protective effects of carotenoids. Many studies were carried out with (i-carotene. The SUVIMAX study, a primary intervention trial of the health effects of antioxidant vitamins and minerals, revealed that a supplementation of p-carotene (6 mg/day) was inversely correlated with total cancer risk. Intervention studies investigating the association between carotenoids and different types of cancers and cardiovascular diseases are reported in Table 3.1.2 and Table 3.1.3. 

In summary, the evidence for the preventive effect of flavonols in cardiovascular disease is growing based on mechanistic, animal, epidemiological, and short-term intervention studies. However, we must learn from the lessons with dietary antioxidants, the last word awaits large-scale intervention clinical trials. 

There are many intervention studies in the literature that demonstrate significant biological effect of PP (76) such as improvement of plasma lipid profile, platelet aggregation, and blood pressure, However, they never have been tested as a therapy for a well-defined disease, A complete review of the most important epidemiological trials on PP is also available (77). 

Even though milk fat contains some fatty acids that may elevate plasma total and LDL-cholesterol levels, which are risk factors for CHD, this effect is balanced by concurrent increases in levels of anti-atherogenic HDL-choles-terol. In addition, saturated fatty acids reduce plasma levels of atherogenic Lp[a] and produce a less atherogenic LDL particle size. Dietary intervention studies, where there was a substantial reduction in saturated fat intake and plasma cholesterol levels, did not produce an improvement in CHD or total mortality. Prospective epidemiological studies provide no evidence that saturated fatty acids are a risk factor for CHD. Indeed, in two large studies, saturated fatty acids were inversely associated with risk. 

Not all epidemiology is observational, and experimental studies have a role to play in evaluating the efficiency of an intervention program to prevent disease (e.g., fluoridation of water). An intervention study at one extreme may closely resemble a clinical trial with individuals randomly selected to receive some form of intervention (e.g., advice on reducing cholesterol levels). However, in some instances it may be a whole community that is selected to form the intervention group. The selection may or may not be random. 

Non-interventional studies In this type of study the medicinal product is prescribed in the usual manner in accordance with the terms of the marketing authorisation. The assignment of the patient to a particular therapeutic strategy is not decided in advance by a trial protocol but falls within current practice, and the prescription of the medicine is clearly separated from the decision to include the patient in the study. No additional diagnostic or monitoring procedures shall be applied to the patients and epidemiological methods shall be used for the analysis of collected data. 

Both the total fat intake and the ratios between FAs of different classes influence the activity of immune cells. Such information was initially obtained through epidemiological human studies, and studies conducted with cultured cells and animal models. These studies showed that EFAs are required for the growth and maintenance of the immune cells, and free FAs are produced and secreted during the activation of these cells. A number of intervention studies regarding the effects of the amount and composition of dietary fat on human immune response have been conducted, results of which are discussed in the following sections. 

Epidemiology and properly controlled human intervention studies to confirm probiotic efficacy... 

Elevated serum cholesterol levels and in particular LDL-cholesterol levels are strongly associated with cardiovascular mortality across the spectrum of epidemiologic studies and pharmacologic intervention studies in primary and secondary prevention trials (Ligure 4.4). In the Cholesterol Treatment Trialists Collaborators meta-analysis of >90,000 patients studied in 14 randomized trials of statin therapy, a reduction in LDL cholesterol of 1 mmol/L (39 mg/dL) was associated with a 12% proportional reduction in all-cause mortality, predominantly driven by a 19% proportional reduction in cardiovascular mortality (45). Among patients with pre-existing heart disease there were 14 fewer deaths per 1000 participants per mmol LDL cholesterol reduction, as well as an approximately 25% reduction in major adverse cardiac events. 

Epidemiologic observations consistendy show lower rates of prostate and breast cancer, and osteoporosis in populations that consume soy (Anderson Garner, 1997 Moyad, 1999 Nagata et ah, 2001a Wu et al., 1998). Intervention studies were conducted to investigate whether these observations are reproducible. These studies will help clarify whether the results reported in epidemiologic studies are causal, and due specifically to soy products (Reinwald Weaver, 2006 Rice Whitehead, 2006). 

More than 20 years ago, Doll and Peto (Doll and Peto, 1981), using international comparisons of exposure prevalences and disease rates, estimated that up to 90% of colonic cancers had a primary dietary contribution. Since then, numerous epidemiological and intervention studies have attempted to identily those components of the diet responsible, but to date it has not been possible to identily conclusively which substances are responsible (Bingham, 2000 Potter, 1999). 

Isoflavonoids also have been reported to have physiological activity in animal and human studies. Besides acting as an estro n mimic, it was reported that the isoflavones found in soybean seeds possess antihemolytic, antifungal, tumorsuppressing, and serum cholesterol-lowering effects. In addition, both epidemiological and dietary-intervention studies indicate that when isoflavones in soybean seeds and in subsequent protein products prepared from the seeds are part of the human dietary intake, those products provide many significant health benefits. - ... 

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