QuestionSBA
QuestionChoice
A retrospective cohort study begins with a cohort of patients who have already achieved the outcome that is being evaluated, in this case bladder cancer. The study investigators then look back in time i.e. retrospectively, to identify whether the cohort were exposed or not exposed to the given risk factor, in this case aniline dyes. The exposure has already occurred. This is a type of observational study.
53262
a
Retrospective cohort study
QuestionChoice
Case control studies analyse those with the disease (cases) versus those without (controls) and look retrospectively back in time to see if exposure occurred to a risk factor. This is not a case control study therefore; if this were, the study design would be as follows: the history of individuals with bladder cancer and individuals without bladder cancer are reviewed to see if they had exposure to aniline dyes in the past or not.
53265
d
Case-control study
QuestionChoice
A cross-sectional study is when a snap-shot is taken of a population at a specific point in time to identify the prevalence or frequency of a certain risk factor or disease. This is not a cross sectional study. This is not a cross-sectional study, since it is not giving us an idea of the frequency or prevalence of either aniline dye exposure or bladder cancer within the population.
53263
b
Cross-sectional study
QuestionChoice
A prospective cohort study starts with two groups of individuals who are either exposed or not exposed to a certain risk factor, then followed up in time to see if an outcome is obtained. This is not a prospective cohort study, therefore. If it were, the study design would be as follows: individuals who have been exposed to aniline dyes versus not exposed are followed up over a certain period of time to see if they develop bladder cancer.
53264
c
Prospective cohort study
QuestionChoice
This is incorrect because an experimental study is a type of interventional study. This involves assessing the effect of an intervention. The researcher is able to control the variables and interact with participants which is different to an observational study. A common experimental study design is that of a randomised controlled trial.
53266
e
Experimental study
Concept
Chapter
# Definition 

A type of clinical study in which participants are assigned to groups that receive one or more intervention/treatment (or no intervention) so that researchers can evaluate the effects of the interventions on biomedical or health-related outcomes.

# Types of interventional trials 

A randomized control trial is the strongest type of interventional trial, but other forms include non-randomised controlled trials, pre-post studies and quasi experiments.

A pre-post study is a study in which occurrence of an outcome is measured both before and after an intervention is administered; it is in this way that the effect of the intervention can be properly assessed. If the occurrence of the outcome was only measured after the intervention; the exact effect of the intervention cannot be determined.

Another form of trial is a crossover randomized control trial. A crossover RCT is a type of interventional study design where study participants intentionally “crossover” to the other treatment arm.

# Uses 

Interventional studies are used to answer study questions relating to either therapeutic agents, and evaluating the efficacy of therapeutic agents, or are used to assess mechanisms of preventing potential causes of damage.
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605
Interventional studies
Topic
51
Medical Statistics
10713
A retrospective cohort study is a type of observational research that looks back at existing data to compare outcomes between groups that were exposed to a particular factor and those that were not.
A study looking at risk factors associated with bladder cancer disease recruit 500 patients diagnosed with transitional cell carcinoma of the bladder. The study found that 250 of the patients were exposed to aniline dyes during their earlier stages of their lives, whilst 250 were not, and concluded that aniline dyes may be a risk factor associated with the development of transitional cell carcinoma.

Which of the following study design is described in the question stem?
a