epidemiology Flashcards
infectious diseases terms
IP - symptoms
latency period - infectiousness
post - morbid period
non infectious diseases terms
induction period - the period of time from causal
action until disease initiation
latent period - detection
types of observational studies
analytical - control group
descriptive - no control group/comparison
types of analytical studies
ecological - dealing with populations
cross sectional /prevelence
cohort
case control - retrospective
CCCE
Descrtiptive studies explain
divided into case report (rare diseases)or case series ( larger group of patients with a single disease
:) provides detailed info so we get to know a lot about rare diseases, etiology , pathogenesis, etc
:( susceptible to bias
:( can’t directly transfer to clinical practice as there is a great level of uncertainty
analytical studies describe
usually for testing hypothesis for the cause of a disease
ecological studies
a type of analytical study
DEALING WITH POPULATIONS
TAKES PRE- EXISTING DATA
NO TIME DIMENSION - so we cannot prove a causal relationship
:( ecological fallacy
prevalence studies /cross sectional
a type of analytical study
no time dimension
:) provides info about prevalence
:( not suitable for rare diseases
case control
a type of analytical study
RETROSPECTIVE - looks back from the outcome of the disease to the exposure
- contains 2 or more groups (cases+ control)
- 3 steps 1. selection of cases 2. matching 3. elimination of bias
:) can be used for rare diseases (unlike cross sectional)
:) effieicnet in terms of time + resources
:) fast evaluation of chronic diseases
:( lack of representativeness
:( susceptible to selection + misclassification bias
cohort studies
a type of analytical study
can be retrospective or prospective
example framigham heart study which is an example of retrospective
:) can detect a causal relationship
:) gives you info on incidence
:) can investigate several outcomes from 1 exposure
:( costly and time consuming
:( need large populations
:( ethical problems
:( following up on peoople can be difficult subjects may be lost!
what can we divide epidemioligcal studies into
- observational
- experimental
experimental studies
contains 2 groups, a control + experimental
examples :
randomised control trials
field trials
community trails
Types of interventions:
Types of interventions:
Prophylactic - target on prevention (e.g. vaccines)
Diagnostic - target on evaluation of new diagnostic procedure
(e.g. new lab test to a gold standard, etc.)
Therapeutic - target on treatment (e.g. new drug)
types of intervention trials
Community trials – a research study, carried out in a realistic community setting, that can involve an individual-level
intervention, a community-level intervention or both;
Clinical trials – a research study to test new methods of
screening, prevention, diagnosis or treatment of a disease,
carried out in hospital settings;
Laboratory experimental trials - a research study, usually
carried out on animals or tissues in laboratories.
clinical trails
- randomised control (gold standard for drug testing)
2,. non randomised
4 phases
phase 1- determine the non toxic dose on animals or healthy people - Is the drug actually safe?
phase 2 - clinical efficacy of the therapy
phase 3- monitor sides effects and COMPARE to the other treatments, and confirm the effectiveness
phase 4- any long term side effects?
define natural history of disease
The course of a disease from its onset to its
resolutions (complete/partial recovery or death) is defined
as the natural history of a disease
- Natural history of diseases could be also classified into
two broad categories: acute and chronic. Acute diseases
(infections) have short natural histories. Chronic disea
stages of natural history of disease
- without a disease
2.beginning of the disease
3.asymptomatic stage - clinical diagnosis
- disease development
- exit of a disease
types of ocntrols in intervential trials
- placebo concurrent cortol grouo
- dose related concurrent contolr group
- active concurrent control group
4.no tx concurrent controll group - historical control
what is intervention
The exposure under investigation is applied by the investigator
Aim= To investigate a possible causal relationship by exposing one or more groups of patients to a factor (treatment) and compare results to one or more control groups that are unexposed to this factor.
Investigator decides which subjects are to be exposed and which not (closest analogy of lab. Experiment in epidemiology).
aim of intervention trial
To investigate a possible causal relationship by exposing one or more groups of patients to a factor (treatment) and compare results to one or more control groups that are unexposed to this factor.
