L11. Aetiology and Risk Factors of Disease Flashcards
What is the difference between descriptive and analytical research questions?
Descriptive describes a condition where as analytical gives a cause and effect
What are the different types of study designs?
Case reports Ecological Cross-sectional Case-control Cohort Clinical Trials
What is the difference between an observational and an interventional study?
Observational is a simple observation without any external intervention while an interventional study is when the circumstances of the subjects are changed.
What are longitudinal studies? Why are they beneficial?
They are studies where there is follow up of the subjects over time. It preserves the time relationship and gives a strong confidence in the cause and effect relationship and the temporal relationship.
What is prevalence?
The number of existing cases of an outcome in a defined population at one point in time
= Number of cases/ total population
It is expressed as a PROPORTION or PERCENTAGE
What is incidence?
The number of NEW cases of an outcome of interest from a defined population during a time interval.
It is a RATE (per year)
Can thus only be drawn from longitudinal studies
What is the Risk?
The probability of disease occurring in a disease free population during a specified time period.
= new cases/population at risk over time
It has the underlying assumption follow up is for the full time
What is the Rate?
The probability of a disease occurring in a disease free population during the sum of INDIVIDUAL FOLLOW UP PERIODS.
=new cases/population at risk/person times
It takes into account the fact that not all subjects are followed up for the same amounts of time
What are the two types of associations that can be made in studies? How are they different?
Correlation
Cause and Effect
There is a relationship derived in cause and effect whereas correlation is a weaker association between 2 variables.
What is Relative Risk?
“Risk Ratio or Rate Ratio”
A relative magnitude of chance that the outcome is associated with the exposure
“Exposure to the risk increases the liklihood of the outcome by the relative risk”
= Re/Ru
What is the Attributable Risk?
Gives an absolute measurement of the magnitude of change of that particular rate
AR = Re - Ru
What is the Attributable Risk Percent?
The proportion of the incident decrease among the people exposed
How many of the exposed people develop outcome DUE TO THAT EXPOSURE
ie. The percentage of the people with the outcome that have it as a result of the exposure to a risk
= [(Re-Ru)/Re] x 100
What is the population attributable risk?
An indication of additional risk/rate of the outcome to the WHOLE population due to exposure.
Rt (risk/rate of total population inclusive of both exposed and unexposed)
PAR = Rt - Ru
What is the population attributable risk percent?
PAR% = [(Rt-Ru)/Rt] x 100
Proportional of incident outcomes among the whole population that is due to the exposure
How much of the WHOLE population who have the outcome have it as a result of exposure?
What are some of the bradford hill criteria for causality?
Temporal relationships, strength of findings. consistency, specificity experimental evidence
