Suppose you want to design a study to further validate the well-established asso

Question

Suppose you want to design a study to further validate the well-established association between smoking cigarettes and lung cancer. Answer the following questions:

Assuming lung cancer takes at least 20 years to develop after the first cigarette smoked, which observational study design would be most appropriate? Why?

Given the above, provide a hypothetical study. Be specific on all aspects of the study (e.g. how you would define the exposure and outcome, how you would measure the association and test for significance, limitations due to confounding, bias or chance, etc…)   

Explanation / Answer

Analytical study:

The aim of analytical study is to identify and evaluate the cause and risk factors associated with a disease.

Analytical study design has 2 types

In experimental analysis scientists intervenes by giving presence and absence of variables of the disease and analysis is conducted.

Observational analysis is the scientists will not intervene, they just observe and analyse.

Observational analysis can be of 2 types

Cohort study:

Cohort means – set of people. Here group of people are studied for disease form, mortality form, cause of death etc.

Study design:

Cohort study can be prospective or retro prospective:

Prospective: observing from the present to the future.

Retro prospective: observing from past to present.

Prospective cohort study is time consuming and will have to wait for the disease outcome and follow up is difficult. Retro prospective is better because data is already available and disease outcome also can be analysed immediately.

Advantages: good for comparing large exposures, can calculate rate of disease in exposed and unexposed over time.

Limitations:

Attribute bias:

Case control observational studies:

The main difference between the cohort and case control is that, presence of control to compare the outcome.

Study design:

Advantages:

Quick to conduct, inexpensive, existing records can be used.

Bias in case control studies:

Discussion:

Case control study is the best used study to relate smoking and lung cancer, which was compared with the control of non smokers. Also smokers family history with disease, whether they were also smokers was analysed.

Case control study is best for understanding the disease which is caused due to exposure than cohort study because the use of control gives much more detailed analysis.

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