Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PASS > semester 2 > Flashcards

semester 2 Flashcards

1
Q

what is the principle of evidence based medicine?

A

use of current best evidence in making decisions about the care of an individual patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the difference between descriptive and inferential statistics?

A

descriptive = describing data
inferential = analysing data + drawing conclusions from the data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is epidemiology?

A

study of distribution and determinants of health-related states or events in a specified population
and the application of this study to control health problems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the 2 methods used to carry out epidemiological investigations?

A

Surveillance + descriptive studies (used to study distribution):
* one group studied
* no explicit hypothesis
* study ends in development of possible hypothesis regarding cause + effect relationship

Analytical studies (used to study determinants)
* 2 or more groups studied for comparison
* definite hypothesis
* reject or accept hypothesis at end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the requirements of a sample population?

A

representative
unbiased (on target)
precise (well grouped)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the 2 types of validity?

A

internal validity:
* free from confounding, bias or random error

external validity:
* degree to which results from study can be applied to population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the 2 types of error?

A

Chance error (random):
* due to sampling variation (people selected)
* reduces as sample size increases

Bias error (systematic):
* difference between true value + expected value
* doesnt reduce with increase in sample size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the 2 types of bias?

A

selection bias:
* sample isnt representative of entire population
* groups within a study may not be comparable
* workers usually exhibit lower overall mortality than general population

Information bias:
* recall error - difference in recollection from study participants
* observer or interviewer has preconceived expectations or knowledge that influence result
* measurement errors
* misclassification - participants put in wrong group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the different measurements taken in a survey?

A
  • prevalence (absolute risk)
  • incidence (absolute risk)
  • incidence rate ratio (relative risk)
  • risk ratio (relative risk)
  • odds ratio
  • risk difference
  • person years
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is meant by the term prevalance and how is it calculated?

A
  • proportion of people who have disease at any given point in time
  • counts people with disease (old and new)
  • determines burden of disease
  • useful to determine resource allocation

prevelance = num of people with disease / total population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is meant by the term incidence and how is it calculated?

A
  • num of new cases for disease in a given time frame
  • useful when monitoring epidemics
  • reported as a rate

incidence rate = num of new cases / sum of patient time at risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is meant by the term incidence rate ratio and how is it calculated?

A
  • compares incidence rate in one group to another to see if exposure is associated with condition

IRR = incidence rate in GP 1 / incidence rate in GP 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is meant by the term relative risk and how is it calculated?

A
  • determined in cohort study where there is a consistent follow-up for all patients

relative risk = absolute risk ratio of GP A / absolute risk ratio of GP B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is meant by the term odds ratio and how is it calculated?

A
  • comparison of odds of disease in one group compared to another

odds ratio = ad / bc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is meant by the term risk difference and how is it calculated?

A
  • difference in risk of an event in GP A compared to GP B
  • no difference = 0

risk difference = absolute risk of GP A - absolute risk of GP B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is meant by the term person years and how is it calculated?

A
  • sum of total time of everybody followed up in a study

e.g. 1000 people followed up for 1 year = 1000 person years

17
Q

what is the 95% confidence interval and how is it calculated?

A
  • the range within which we can be 95% certain that the true value lies within
  • if P > 0.05 = findings are statistically insignificant and failure to reject null hypothesis
  • if P < 0.05 = findings are statistically signifant and null hypothesis is rejected
  • if 95% CI spans over 1 (e.g. 0.5 - 1.52) then P > 0.05

(OR / e.f) to (OR x e.f)

18
Q
  1. what is confounding?
  2. how can you overcome confounding?
A
  1. mixing of effect between exposure, the disease and a third variable (the confounding variable) - age, sex, ethnicity, smoking
  2. minimise by matching case and controls using confounding variables + standardisation
19
Q
  1. what are ecological studies?
  2. what are issues with ecological studies?
A
  1. identify groups of people to study (countries rather than individuals) + gather data on group-level characteristics
  2. measurement variation, confounding + chance
20
Q
  1. what are cross-sectional surveys?
  2. what are the issues with cross-sectional surveys?
A
  1. surveys which measure exposure + outcome simultaneously + is most useful in determining prevalence + used for individuals
  2. sampling bias, participant bias, chance + confounding
21
Q

what are case-control studies?

A
  • always retrospective (looking back in time)
  • groups of cases and non-cases
  • ascertains previous exposure status
  • compares levels of exposure in case + controls

Analysis:
* only odds ratio

22
Q
  1. what is the difference between conventional case-control study and nested case-control study?
  2. what is the advantage of nested case-control study?
A
  1. conventional = always retrospective data whereas nested = data from a database of concurrent or prospective cohort study
  2. incidence rates can be calculated, can collect more detailed info for a minority of participants
23
Q
  1. what are the advantages of case-control studies?
  2. what are the disadvantages of case-control studies?
A
  1. good for rare diseases, cheap + quick
  2. selection bias, information bias and confounding
24
Q

what are cohort studies?

A
  • always prospective look forward in time
  • group individuals according to level of exposure
  • select outcome free individuals
  • ascertain outcomes for everyone
  • compare incidence rates for each group

Analysis:
* can use odds ratio or rates ratio

25
Q

what is the difference between (concurrent or prospective) and (historical or retrospective) cohort studies?

A

concurrent or prospective:
* find exposed and unexposed at current time
* wait for outcomes to occur

historical or retrospective:
* use data from pre-existing records
* look at past exposure and determine whether exposure has occured

26
Q
  1. what are the advantages of cohort studies?
  2. what are the disadvantages of cohort studies?
A
  1. better at studying a range of different outcomes + studying rare exposure
  2. some people may drop out so cant follow up, information bias, confounding + expensive
27
Q

what is PICO?

A

population
intervention
comparison
outcome

28
Q

what is the standardised mortality ratio and how is it calculated?

A

ratio between observed num of deaths in study population / num of deaths that would be expected in general population

SMR = observed num of deaths / expected num of deaths

PASS (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions