M1: Experimental Epidemiology Flashcards
Intervention or experimentation involves attempting to change a variable in one or more groups of people. This could mean the elimination of a dietary factor thought to cause allergy, or testing a new treatment on a selected group of patients
Experimental epidemiology
The effects of an intervention are measured by comparing the _______ with that in a _______
outcome in the experimental group, control group
What is ALWAYS required for study participants to sign before taking part in any experiment
Informed Consent
3 designs of an interventional study
(RaFiC)
- Randomized controlled trial
- Field trial
- Community Trial
is an epidemiological experiment designed to study the effects of a particular intervention, usually a treatment for a specific disease
randomized controlled trial
Subjects in the study population are (randomly allocated) to intervention and control groups, and the results are assessed by comparing outcomes
randomized controlled trial
is an epidemiological experiment involving people who are healthy but presumed to be at risk; data collection takes place “in the field,” usually among non-institutionalized people in the general population
Field Trials
Purpose of Field trials
Prevent diseases that may occur with relatively low frequency
epidemiological experiments that are often logistically complicated and expensive endeavors
Field Trials
One of the largest field trials was that testing of what?
Salk Vaccine for poliomyelitis
Epidemiological experiment that can be used to evaluate interventions aimed at reducing exposure
without necessarily measuring the occurrence of health effects.
Field Trials
In this form of experiment, the treatment groups are communities rather than individuals.
Community trials
This is particularly appropriate for diseases that are influenced by (social conditions), and for which prevention efforts target group behavior.
Community Trials
is a good example of a
condition appropriate for community trials
Cardiovascular
4 Limitation of community trials
(LISR)
1. Limiting in design
2. Impossible to isolate during intervention
3. Small scope
4. Random allocation not practical
_______________________________
Basically it is too small hence the design is limited and it cannot be randomized nor isolated.
is new to the pyramid of evidence strength
Systematic Review/Meta-Analysis
THREE MAIN TYPES OF OBSERVATIONAL
STUDIES
(3Cs)
Cross-sectional study
Cohort study
Case-control study
THREE BASIC CHARACTERISTICS of Experimental studies
(CoMRand)
- Manipulation
- Control
- Randomizations
Diets administered by James Lind in his treatment for scurvy
(COVENS)
- Cyder (quart/day)
- Elixir vitriol (25 for 3x/day)
- Vinegar (2 spoons for 3x/day)
- Sea water (Half pint/day)
- 2 oranges and 1 lemon (everyday)
- Nutmeg (3x/day)
Most common experimental study
randomized clinical trial
Trial where they test the efficacy of a treatment
Clinical trials
assess effectiveness of (prevention) program in a (community)
COMMUNITY INTERVENTION TRIALS
5 Types of treatments that can be tested in (clinical trials)
(DPRk HeL)
- Drugs
- Procedures
- Risk factor modifications
- Health Education
- Lifestyle modification
A method used to prevent bias in research; a computer
or a table of random numbers generates treatment assignments, and participants have an equal chance to be assigned to one of two or more groups
Randomization
WHY IS RANDOMIZATION IMPORTANT?
So all groups are as alike as possible
5 PROBABILITY SAMPLING DESIGNS
(MRS. CluS)
- Random
- Systematic
- Stratified
- Cluster
- Multi Stage
Most basic type of sampling design. Every element in the population has an equal chance of being included in the sample
SIMPLE RANDOM SAMPLING
3 Types of Blinding (Masking)
(OSD)
- Open Label
- Single Blind
- Double Blind
Blinding where patient and physician know treatment assignment
Open label
Blinding where patient does not know, but physician does
Single blind
Blinding where neither the patient nor the physician knows the
treatment assignment (statistician or computer
programmer knows the treatment assignment)
Double blind
The simplest of all design based on randomization and replication
Completely randomized design
one in which the number of experimental units per block is equal to the number of treatments and every treatment occurs once and only once in each block, the order of treatments within a block being randomized
Randomized Complete Block Design
An experiment whose design consist of (two or more factor) each with different possible values or ” levels
Factorial design
At least one characteristic of a true experiment is
missing, either randomization or the use of separate control group
Quasi experiment
Example of Quasi experiment
Handwashing Technique Instruction and Helminthiasis
Directionality of a Cohort Study
Always forward
Timing of a cohort study
Prospective or Retrospective
Directionality of Case Control Study
Always backwards
Timing of Case control study
Always retrospective
Directionality of Cross sectional study
Always non-directional
Timing of Cross sectional study
Always Retrospective
5 TYPES OF STUDY DESIGN
● Randomized Clinical Trial ● Cross-Sectional Study ● Prospective Cohort Study ● Retrospective Cohort Study ● Case-Control Study
an approach that follows research participants over a period of time (often many years)
Cohort study
A study that compares two groups of people: those with the disease or condition (under study) and a very similar group of people (who do not have the disease) or condition
Case Control study
involves looking at data from a population at one specific point in time. The participants in this type of study are selected based on particular variables of interest.
Cross sectional study
