General Epidemiology Flashcards
Portions of death certificate
First portion (personal details, date n time)
Second portion (cause of death)
Types of Causes of death in death certificate
Immediate cause
Antecedent cause
Underlying cause
Magnitude of health problem is measured by
Morbidity
Mortality
Basic tools in epidemiology
Rates
Ratios
Proportions
Epidemiological methods
Observational studies
Experimental studies
Observational studies
Descriptive
Analytical (ecological/ cross sectional/ case control)
Cohort
Experimental studies
Randomized controlled trials
Field trials
Community trials
Operational definition
Epidemiologist should be able to identify the deseased but also measure it accurately.
Berkesonian bias
Different rates of hospital admission
Types of bias
Selection
Berkesonian
Interviewer
Types of cohort study
Prospective
Retrospective/ non current prospective
Combination (pros+ retro)
Elements of cohort study
Selection of subject
Data obtained
Compassion gp selection
Follow up
Attrition
Losses in trials due to
Death
Migration
Non cooperation
3 criterias of selecting a study group
Representative of reference population
Informed consent (procedure+dangers)
Susceptible to disease
Types of epidemic curve
Common source (single point source)
Propagated epidemics
Slow epidemics
Uses of epidemic curve
Exposure to suspected source to time
Suggest particular infection
Common source /propagated
Retrospective study / case control study distinct features
Exposure and outcome occured before the study starts (presently it is a case)
Backwards from effect
Uses a control/comparison group
Steps of retrospective study
Selection of cases
Selection of control
Matching
Measurement of exposure
Analysis + interpretation
Measurement of exposure may be obtained by
Questionnaire
Past records(hospital+ employment)
Disadvantages of retrospective study
Bias
Difficult control selection
Dont diiff between associated or causative factors
Odds ratio
Measure strength of association between risk factor and outcome
Evaluation of risk of developing a diseaseamong those exposed as compared to non exposed
Cohort study / prospective / longitudinal / incidence or forward looking study
Obtain additional evidenceto support existence of association between cause and disease
Features of cohort study
Prior to appearance of disease.
Observed longer to determine frequency.
Forward (cause to effect)
Elements of cohort study
Selection of study groups(cohort)
Obtain data on exposure
Selection of comparison group
Follow up
Analysis
Advantages of cohort study
Incidence calculable
Dose response ratio calculable
Minimize misclassification bias
Disadvantages of cohort study
Large no. Required
Longer duration
Attrition problem (loss of follow up)
Selection bias
Ethical problem in case of changes
Limited factors considered
Uses of epidemiology (by morris)
7
Study trend of disease
Community diagnosis
Health services planning+evaluation
Individual risk / chances
Syndrome identification
Completing clinical picture
Causal telationship establishment
4 phases of clinical trial (SEAL)
Safety
Efficacy
Approval
Long term
Types of clinical trials
Randomised controlled trials
Pre-post design
Factorial design
Sensitivity
No. Of positively testing among no. Of diseased
Specificity
No. Of negative test results in total no. Of non-diseased
