epidemiological studies, analysis of cancer

Question 1

what are the three types of cohort studies

Answer 1

prospective, retrospective and ambi-directional cohort

Question 2

what is a cohort study

Answer 2

group of people with similar exposures

Usually In a defined POPULATION.

Question 3

what is a retrospective cohort study

Answer 3

a study in which outcomes have occurred before the start of the investigation

Question 4

what are ambi-directional cohort?

Answer 4

combines prospective and retrospective, the cohort is identified from past records and assesses the date for the outcome. the same cohort is followed up prospectfully in the future for further assessment of outcomes.

Question 5

what is the relative risk calculation

Answer 5

incidence risk among an exposed group divided by incidence risk amongst non-exposed group

Question 6

what are the advantages and disadvanatages of cohort studies

Answer 6

• incidence can be calculated
• several possible outcomes related to exposure can be studied simultaneously
• not suitable for rare diseases
• time consuming and expensive
• study may alter peoples behaviour

Question 7

what types of bias are common in cohort studies

Answer 7

differential loss, contamination, selection bias, information bias and missclarification bias

Question 8

what is a case control study

Answer 8

observational study of those with the disease of interest and suitable control group without disease

Question 9

what are the three distinct features of case-controls

Answer 9

• exposure and outcome have occurred before the start of the study
• study proceeds backwards effect - cause (always retrospective)
• uses control of comparison group

Question 10

what is a case

Answer 10

a person in the population who have been identified as having the disease under investigation

Question 11

what is a control

Answer 11

person/persons in a comparison group that differs in disease extreme,e in not having the outcome that is being studied

Question 12

what are the examples of case-control bias

Answer 12

selection, information and confounding

Question 13

what is an odds

Answer 13

ration of the number of ways an event can occur to the number of ways an event can’t occur

Question 14

what is an odds ratio

Answer 14

ratio of the odds that the cases were exposed to the odds that the controls were exposed too

Question 15

advantages of case-control studies

Answer 15

commonly used in outbreak investigation
relatively inexpensive
important to understand new diseases only realistic study design for uncovering aetiology of rare diseases

Question 16

disadvantages of case-control study

Answer 16

susceptible to bias, i restricted to a single outcome, especially susceptible to recall bias

Question 17

cross-sectional studies

Answer 17

an analytical investigation in which subjects are sampled at a fixed point or period of time and the association between the concurrent presence or absence or risk factors and diseases are investigated

Question 18

what is descriptive cross-section

Answer 18

presence of disease, disability and symptoms of ill-health. measurement of variables

Question 19

what is analytical cross-sectional

Answer 19

strength of association between disease or risk factors

determinants of predictors of disease

Question 20

advantages of cross-sectional studies

Answer 20

• less costly
• easy and quick
• provides an estimate of the prevalence of a disease
• used for chronic conditions with low case fatality

Question 21

disadvantages of cross-sectional studies

Answer 21

• does not provide incidence
• prone to bias
• weak design for providing causality

Question 22

what are gene interaction studies

Answer 22

the different effects of environmental exposure on disease risk in subjects with different genotypes

Question 23

what are methods to analyse traditional genetic designs

Answer 23

adoption studies, twin studies, family studies

Question 24

what are advantages in gene environment interaction study

Answer 24

An understanding of gene- environment Interaction has Important
implications for public health - Alds in predicting disease rates

Question 25

disadvantages of traditional genetic designs

Answer 25

Lack of replication
Does not account for whether environmental
effects are additive , multiplicative o r interactive

Question 26

what are genome wide association study

Answer 26

An approach that Involves scanning biomarkers from DNA of many people in order to find genetic variation associated w ith a particular disease field phenotypes

Question 27

what are the advantages of genome-wide association

Answer 27

can lead to the discovery of biological mechanism s
can study low-frequency and rare variants
successful at identifying novel variant- trait associations

Question 28

disadvantages of genome wide association

Answer 28

Doesn’t necessarily pinpoint causal variants a n d genes

• Has Lim ited clinical predictive’ value
• cannot identify all genetic determinants.