Module 1 (GATE frame) Flashcards
Epidemiology
The study of how much ‘dis-ease’ occurs in a population and of the factors that determine differences in dis-ease occurrence between populations
The main goal of epidemiology
Measure the frequency of health and dis-ease in different populations to find out the causes of poor health and how to improve it
Measuring epidemiology
The occurrence of dis-ease (N) in groups of populations (D) at one point or over a period of time (T) - E = N/D/T
Occurrence
Describes the transition from a non-diseased state to a diseased state; big change over a period of time usually due to a single component
Age standardisation
Process of converting the different age structures in each population into one (standard) population age structure and working out the disease rates
Categorical data
Quantitative data grouped into categories
Numerical data
Quantitative data which takes on numerical values; can be grouped into categorical data by making a large range of values classify as a group/outcome
Triangle in GATE frame
Population - overall study/participant population representing the denominator; study setting, eligible population and participants willing to take part
Circle in GATE frame
Study-specific sub-denominators including the exposure group(s) and comparison group
Exposure group
Group(s) of participants subject to a certain exposure; studies can have multiple exposure groups
Comparison group
Group of participants not subject to the certain exposure; studies can only have one comparison group
Square in GATE frame
Outcomes - dis-ease outcomes; can be split into more than 4 squares where multiple exposures/dis-ease outcomes can be classified to more than 2 categoris
Arrow in GATE frame
Time - horizontal or vertical representing the time when or during which the outcomes are measured
Cohort study
Follow-up study; investigates associations between risk or prognostic factors (exposures) and dis-ease incidence in different groups of individuals; commonly used for investigating risk factors or dis-ease with large effects; incidence or prevalence
Cohort study advantages
Usually cheaper than RCTs; exposure usually measured before outcome, avoiding recall bias and providing clear time sequence between exposure and dis-ease outcomes
Cohort study disadvantages
Confounding is common, can hide effects when they are small; maintenance error is very common in long term studies because the exposure is not controlled by investigators (loss due to follow-up)
Cohort study main design features
Longitudinal, observational (non-experimental) where participants are allocated to EG and CG by measurement and dis-ease outcomes are measured during follow-up
Cross-sectional study
Measures the population, exposure and dis-ease frequency at the same time; investigates associations between risk factors and dis-ease prevalence in the groups; prevalence
Cross-sectional study advantages
Generally cheaper and can be completed more quickly than RCTs or cohort studies; best design for assessing the prevalence of dis-ease in a population; no maintenance error because there is no follow-up
Cross-sectional study disadvantages
Uncertain time sequence (possible reverse causality) which limits interpretation of cause and effect so not useful for causes of disease; confounding common so not useful for benefits of drugs
Cross-sectional study main design features
Cross-sectional, observational (non-experimental) where participants are allocated to EG and CG by measurement and dis-ease outcomes are measured at the same time
Randomised controlled trial
Participants are randomly allocated to EG and CG; need to always check for differences between the two groups at the beginning of the study (baseline comparison); can be single-blind or double-blind
Randomised controlled trial advantages
Blind studies prevents participants and measurers from acting differently due to their knowledge of the intervention, decreases chance of confounding; best study for effect of treatments if practical and ethical; groups similar at beginning of study; any difference on outcomes can be attributed to the intervention
Randomised controlled trial disadvantages
Not useful for risk factors of disease, can be unethical or impractical (do a cohort study instead); logistically difficult (long-term follow-up) and costly; maintenance error is common - random error
Randomised controlled trial main design features
Longitudinal, experimental; participants randomly allocated to either study exposure or comparison exposure and dis-ease outcomes measured during a follow-up period
Ecological study
Comparisons of groups of populations (cities, regions or countries) instead of groups of individuals; can be longitudinal or cross-sectional
Ecological study advantages
Generally cheaper and quicker than all other study designs because it uses data already collected; useful when the majority of some populations are exposed but others are not; efficient for rare outcomes
Ecological study disadvantage
Confounding is very common