Observational Epidemiology Flashcards
When might an observational study be needed?
When an association between a potential cause and effect is found
What are the two types of epidemiological studies?
Descriptive
Analytic
What are the three types of descriptive study?
Ecological
Case reports/case series
Cross-sectional
What are the two categories of analytic study?
Observational
Interventional
What are the two types of observational study?
Case-control
Cohort
What is the one type of interventional study?
Clinical trial/RCT
How do observational studies different from interventional studies?
Observational studies look at naturally occurring causal relationships, whereas RCTs study controlled exposures
What are the three main things to consider in an observational study before looking at causality?
Bias
Confounders
Chance
What are the two broad types of bias which might be encountered in observational studies?
Selection bias
Information bias
What is selection bias?
The selection process of exposure groups is systematically different, therefore groups cannot be validly compared with each other or the general population
What types of bias fall under selection bias?
Sampling bias
Responder bias
Concerning occupational exposure what is the healthy worker effect?
The idea that people who are healthy enough to work cannot be compared with general practice, which includes elderly people and people unable to work - therefore the participants do not reflect the general population
What is information bias?
When the process of obtaining data from different groups differs systematically
What are 5 types of information bias?
Recall bias
Recording bias
Interviewer bias
Lost-to-follow-up bias
Social acceptability bias
What is recall bias?
The idea that unhelathy patients think more about a disease more than health patient,s therefore have more knowledge
What is recording bias?
The idea that unhealthy patients have more extensive medical notes than healthy patients
What is interviewer bias?
When the interviewer knows whether the patient has had the disease or not, and they subconsciously change their questions
What is lost-to-follow-up bias?
Patients lost to follow-up are more likely to be unhealthy patients with data of interest
What is social acceptability bias?
When the interviewee attempts to make their answers more socially acceptable
What is a confounding factor?
Something associated with both the disease and exposure, which could cause the disease and explains the apparent association between the exposure and the disease
What method can be used to check to see if factors are confounding or genuine?
Stratification
What does stratification involve?
Grouping results into subgroups of an exposure factor, and comparing how other exposure factors match up with that factor (or not)
What is the aim of stratification?
Identify and remove confounding factors by disentangling their effects
Give three ways in which disease can be measured (epidemiologically)
Incidence rate
Rate
Point prevalence