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Cohort Study

Vitamin E Consumption and the Risk of Coronary Heart Disease in Men Describe the study research design The research design conducted by Rimm et al. was a good example of a prospective cohort study. It involves the identification of the population that does not have the disease that is tested, and collects information on the exposure of the subjects to the risk factors, and involves following up the subjects over a period. Strengths of the research design The strength of choosing a prospective cohort study is that subjects are not required to recall past events that may have influenced results.

Thus, there is a limited chance of bias occurring as the data is collected before the disease under study develops. Weaknesses of the research design Carrying out a prospective cohort study requires long-term record keeping and increased cooperation with the subjects. As such, there is an increased chance of selection bias, as the researchers are more likely to include people they know will cooperate. Such people may not be a perfect representation of the general population. Method of dietary assessment

When considering dietary assessment, the researchers utilized questionnaires, which assessed their intake of different vitamins and other nutrients. Method used When considering the method, the researchers examined about 39,910 healthy male professionals who were between the ages of 40 and 75 years assessing their dietary uptake through questionnaires (Rimm 1450). There was a follow-up four years later, which reassessed the health of the subjects. Strength and weakness of the method

The use of a detailed questionnaire provided important data that would assist in making an accurate prediction on the relationship between different nutrients and heart disease. However, the method only used one class of subjects; there should have been participants and a control group. Doing so would have made the researcher findings more accurate. Was supplement considered? When considering the Vitamin E intake, supplement use was considered as part of the questionnaire questions, considering that a multivariate relative risk of Coronary Heart disease was discovered for those who took it.

Which outcome was examined? The outcome examined was the relationship between vitamin E intake and the development of Coronary Heart Disease among men. What is relative risk? Relative risk is the ratio of probability that a particular event will occur in an exposed group to the event occurring in a group that is not exposed to the variables. Relative risk in association with levels of vitamin E intake? Relative risk is the measure that estimates the size of the effect of taking Vitamin E compared to other intervention that may reduce Coronary Heart Disease.

Which range of vitamin E intake was linked to lower levels of heart disease? The consumption range of 100 -249 IU of Vitamin E led to a 95 percent confidence interval, and reduction in the development of heart disease, compared to those who took less than7. 5 UI daily. Which confounders were controlled? AGE , bady mass index, currnt smoking, hypertintion, asprin use, exersies. Multivitamin Research Study Describe the study research design The study research design used by Sesso et al. appears to be an intervention trial research study.

In the study, the researcher assigned the participants to either receive or not receive multivitamins, which represents the nutritional intervention, and then observed them over a period, allowing them to observe whether the intervention influences the occurrence and development of the disease under investigation. Strengths of the study research design The benefit of the intervention trials is that it provides direct evidence of a cause-and-effect relationship. It is easy to attribute effects of the study to the factors that are investigated.

Weakness of the study research design However, the use of intervention trials is that it can assess a limited number of factors at a time, especially due to limited resources required for the study. Describe the vitamin intervention (amount, type, and frequency of consumption) 1- Dietary Supplement: Vitamin E(400 IU synthetic alpha-tocopherol or its placebo on alternate days). 2- Dietary Supplement: Vitamin C(500 mg synthetic ascorbic acid or its placebo daily). 3- Dietary Supplement: Multivitamin(Centrum Silver or its placebo daily). – Dietary Supplement: Beta-carotene(50 mg Lurotin or placebo on alternate days).

Did the study determine compliance to the intervention? Considering the high level of control maintained during the experimental research, there is a high level of compliance with the intervention. Did they also consider dietary intake of vitamins? Dietary intake of vitamins was also considered, as food patterns which were instrumental in the prevention of cardiovascular disease. Which outcome was examined in the study

When considering the outcome, taking daily multivitamins did not reduce any major cardiovascular events, stroke or CVD mortality after a decade of treatment (Sesso 1752). To determine whether long-term multivitamin supplementation decreases the risk of major cardiovascular events among men. What were the results? Compare the difference in the risk (or hazard of the disease) among the groups. Taking multivitamins daily did not reduce major cardiovascular events, stroke or CVD mortality after a decade of treatment and followup. here were 1732 confirmed major cardiovascular events.

Compared with placebo, there was no significant effect of a daily multivitamin on major cardiovascular events (11. 0 and 10. 8 events per 1000 person-years for multivitamin vs placebo, respectively; hazard ratio [HR], 1. 01; 95% CI, 0. 91-1. 10; P = . 91). The effect of a daily multivitamin on major cardiovascular events did not differ between men with or without a baseline history of CVD (P = . 62 for interaction). Was intervention associated with the outcome? No, the intervention was not associated with the outcome.

The multivitamin was not significantly effective in comparison to the placebo. Difference in results of the two studies In the first case study, a cohort study the result was the data do not prove a causal relation, but they provide evidence of an association between a high intake of vitamin E and a lower risk of coronary heart disease in men. However, in intervention trial research study the result was a daily multivitamin did not reduce major cardiovascular events, MI, stroke, and CVD mortality after more than a decade of treatment and follow-up.

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