What is analytical epidemiology?
Analytical epidemiology is considered the how and why of epidemiology, and this branch of epidemiology evaluates one or more predetermined hypotheses about associations between exposure and outcome variables (Merrill, 2013). Analytical epidemiologist makes use of a comparrison group while recording observations and conducting statistical analysis ( Merrill, 2013). There are two types of observational studies that can be conducted; 1) observational exploratory, where a variety of observations are examined to isolate a cause and effect relationship. 2) observational analytical, where the epidemiologist evaluates a specific hypothesis as to the cause of a disease (Merrill, 2013). Analytical epidemiology is also useful when exposure of a potential causative event/substance to a patient, cannot be ethically justified (known negative outcomes) (Merrill, 2013).
Four types of observational analytical studies:
Case control
- This type of study is the most common of analytical studies and frequently involves grouping people into case groups.
- Case control studies isolate a cohort from risk factors and then compares known case groups with control groups.
- This study investigates the case subjects past history to determine the possible causes that may have led to disease acquisition.
- Case control studies begin with an outcome and go backwards.
- Controls used in Case control studies may include hospital controls, general population and special control groups (Merrill, 2013).
Case-crossover
- Compares the frequencies of exposure prior to the onset of a disease, and that of an earlier time.
- It is the study put to use when attempting to identify any preceding events.
- This type of study is very useful in situations where the onset of a disease appears abruptly, or has a known short incubation period.
- In a Case-crossover study, the control is "time" (Merrill, 2013).
Nested Case-control
- A case control study that is conducted within a selected cohort, in a cohort study (see below) (Merrill, 2013).
Cohort study
- Subjects are followed over time to identify the incidncece or natural occurance of a condition or disease.
- This type of study involves a group of individuals who have been exposed or who have acquired the disease to be studied and are then compared to another group that has not been exposed or does not have the disease.
- There are two types of Cohort studies, 1) a prospective cohort study where the predictor variable is measured before the outcome has occurred and 2) a retrospective cohort study in which a historical cohort and situation has been re-constructed with available data (Merrill, 2013).
Four types of observational analytical studies:
Case control
- This type of study is the most common of analytical studies and frequently involves grouping people into case groups.
- Case control studies isolate a cohort from risk factors and then compares known case groups with control groups.
- This study investigates the case subjects past history to determine the possible causes that may have led to disease acquisition.
- Case control studies begin with an outcome and go backwards.
- Controls used in Case control studies may include hospital controls, general population and special control groups (Merrill, 2013).
Case-crossover
- Compares the frequencies of exposure prior to the onset of a disease, and that of an earlier time.
- It is the study put to use when attempting to identify any preceding events.
- This type of study is very useful in situations where the onset of a disease appears abruptly, or has a known short incubation period.
- In a Case-crossover study, the control is "time" (Merrill, 2013).
Nested Case-control
- A case control study that is conducted within a selected cohort, in a cohort study (see below) (Merrill, 2013).
Cohort study
- Subjects are followed over time to identify the incidncece or natural occurance of a condition or disease.
- This type of study involves a group of individuals who have been exposed or who have acquired the disease to be studied and are then compared to another group that has not been exposed or does not have the disease.
- There are two types of Cohort studies, 1) a prospective cohort study where the predictor variable is measured before the outcome has occurred and 2) a retrospective cohort study in which a historical cohort and situation has been re-constructed with available data (Merrill, 2013).