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HaDPop (Semester 2) > Key Points > Flashcards

Key Points Flashcards

1
Q

Define CBR

A

crude birth rate: number of live births per 1000 people

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2
Q

Define GFR

A

general fertility rate: number of live births per 1000 females aged 15-44 years

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3
Q

Define TPFR

A

total period fertility rate: the average number of children that would be born to a hypothetical women in her life

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4
Q

Define fecundity

A

The physical ability to reproduce.

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5
Q

Define census

A

The simultaneous recording of demographic data by the government at a particular time, pertaining to all the persons who live in a particular territory.

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6
Q

Define fertility

A

The realisation of the ability to reproduce as births.

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7
Q

What is fertility increase by?

A

increased sexual activity and better economic climate

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8
Q

What is fertility decreased by?

A

contraception and abortion

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9
Q

What is the use of CBR?

A

describing the impact of births on the size of the population

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10
Q

What is the use of GFR?

A

comparing fertility of fertile female populations

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11
Q

What is the use of TPFR?

A

comparing fertility of fertile female populations without being influenced by age-group structure

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12
Q

Define CDR

A

crude death rate: number of deaths per 1000 people

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13
Q

Define ASDR

A

age specific death rate: number of deaths per 1000 people in a specific age group

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14
Q

What is the SMR?

A

standardised mortality rate: compares observed number of deaths will expected number of deaths if age-sex distribution of the population compared to the reference were identical

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15
Q

Which things affect population size?

A

births (fertility rates), deaths and migration

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16
Q

Who will be missed off a census?

A

Homeless people

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17
Q

What is a fairly common problem in hospitals that leads to statistical errors?

A

classification or coding errors

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18
Q

Define chance

A

the occurrence of events without any obvious cause

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19
Q

Define bias

A

the inclination or prejudice for or against something, considered unfair

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20
Q

Define confounder

A

variable that correlates with both the dependent and independent variables without being on the causal pathway, usually a variable that was not adjusted for

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21
Q

Define incidence

A

The number of new cases of a disease in a population in a specific time period.

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22
Q

Define prevalence

A

The number of people with a particular disease in a population at a given time.

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23
Q

What kind of statistic is prevalence?

A

A proportion

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24
Q

What is the formula for incidence rate?

A

new events / (people x time (yrs))

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25
Q

Define aetiology

A

cause (of a disease)

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26
Q

What is the formula for the IRR?

A

rate B (exposed) / rate A (unexposed)

exposed/unexposed

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27
Q

Rate is a measure of what kind of risk?

A

Absolute risk

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28
Q

Ratio is a measure of what kind of risk?

A

Relative

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29
Q

How is SMR expressed?

A

As a percentage

100 = same risk in both population
>100 = higher risk in study population than reference
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30
Q

What is the null hypothesis if it is a rate and if it is a difference?

A 
rate = 1
difference = 0
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31
Q

Define hypothesis

A

a statement that an underlying tendency of scientific interest takes a particular quantitative value

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32
Q

What does it mean if p

A

we can reject Ho because the probability of getting an observation based on the hypothesis being true is low
Ho is outside the confidence interval
statistically significant

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33
Q

What does it mean if p>0.05?

A

we cannot reject Ho, within the confidence interval and not statistically significant

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34
Q

How do we work out the lower limit?

A

observed value / error factor

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35
Q

How do we work out the upper limit?

A

observed value x error factor

36
Q

What happens as we get more data?

A

error factor gets smaller and confidence interval narrows

37
Q

How do we recruit people in cohort studies?

A

recruit outcome-free individuals and classify them into exposed and unexposed

38
Q

What are the types of cohort study?

A

prospective/concurrent and retrospective/historical

39
Q

What does internal comparison refer to?

A

Comparison of sub-cohorts

40
Q

What does external comparison refer to?

A

Comparison of study group to external reference population.

41
Q

Advantages of cohort studies

A

can study a range of different outcomes, rare exposures and establish exposure precedes outcome

42
Q

Disadvantages of cohort studies

A

expensive (large and resource intensive), time consuming, risk of high number of losses (->survivor bias), not good for rare outcomes

43
Q

What are the Koch’s postulates for?

A

rules used to determine if an infectious agent is the cause of a disease

44
Q

What are the 3 rules of Koch’s postulates?

A

the organism occurs in every case of the disease
the organism occurs in no other disease
on removal from the body and growing in pure culture it can induce the disease anew

45
Q

What are the problems with Koch’s postulates?

A

definition of the disease
difficulties isolating the microbe
no model for examination as cannot ethically transmit a microbe into a healthy human or animal

46
Q

What measures can help prevent infection spreading?

A

protective isolation for susceptible people
preventative isolation for people with the infection
hand washing
antibiotic restriction
try to keep staff to a particular area of the hospital

47
Q

What is Ro?

A

The rate at which an individual infection produces new infections in an individual.

48
Q

What is the formula for Ro and define the constituents?

A

Ro = betaXD

beta = capacity for transmission
X = number of infectious individuals 
D = time period of infectivity
49
Q

What are the results for Ro and interpret them?

A

Ro > 1 : infection propagates

Ro

50
Q

How do we begin a case-control study?

A

find 2 groups of people: one group have the disease (cases) and the other doesn’t (controls) then ask all individuals in groups if they were exposed or unexposed

51
Q

What is a nested case-control study?

A

A case control study within a cohort study

52
Q

What 2 types of bias are case-controls most prone to?

A

selection bias and recall bias

53
Q

What are the 9 Bradford Hill Criteria for Causality?

A 
strength of association
specificity of association
consistency of association
temporal sequence
dose response
reversibility
coherence of theory
biological plausability
analogy
54
Q

Define epidemiology

A

The study of the distribution and determinants of health related states or events in specified populations, and the application of this study to the control of health problems.

55
Q

What is the hierarchy of evidence with the best evidence at the top?

A 
systematic reviews
randomised control trials
cohort studies
case-control studies
cross-sectional surveys 
case reports
56
Q

Define clinical trial

A

Any form of planned experiment which involves patients and is designed to find out the most appropriate method of treatment for future patients with a given medical condition.

57
Q

What is the purpose of a clinical trial?

A

To provide reliable evidence of treatment efficacy and safety.

58
Q

Define efficacy

A

The ability of a health care intervention to improve the health of a defined group of people under specific conditions.

59
Q

What problems would a non-randomised control trial have?

A

allocation bias and confounding

60
Q

How do we conduct a randomised control trial?

A 
identify a source of eligible patients
invite them and gain consent 
randomly allocate patients to treatments
follow up in identical ways 
minimise losses
maximise compliances
61
Q

What does open label mean?

A

The study has not used blinding.

62
Q

When is blinding difficult?

A

surgical procedures
alternative medicine
lifestyle interventions
prevention programmes

63
Q

What is the problem with comparing a treatment with no treatment?

A

We cannot be sure whether the observed difference is due to the new treatment or just because the group were receiving care.

64
Q

What is the placebo effect?

A

Even if the therapy is irrelevant to the patient’s condition, the patient’s attitude to their illness, and the illness itself, may be improved due to a feeling that something is being done about it.

65
Q

Define placebo

A

An inert substance made to appear identical to the active formulation. Used to cancel out any placebo effect.

66
Q

What is As-Treated Analysis?

A

You only measure the outcomes of the people who took their medication as instructed.

67
Q

What is Intention-To-Treat analysis?

A

You measure everyone’s outcome whom you intended to treat whether they took their medication as intended or not.

68
Q

What are the effects of As-Treated analysis?

A

randomisation is lost, selection bias (non-compliers are likely to be systematically different) and confounding

69
Q

What are the 4 ethical principles?

A

beneficence (helps them)
non-maleficence (does no harm)
autonomy (patient’s decision)
justice (non-discriminating)

70
Q

Define clinical equipoise

A

There is reasonable uncertainty or ignorance about the best treatment.

71
Q

What are the features of a narrative review?

A

biased, subjective and based on the view of one expert

72
Q

What are the features of systematic reviews?

A

other people look at the evidence, unbiased and objective

explicit, transparent and reproducible

73
Q

Define meta-analysis

A

A quantitative synthesis of the results of 2 or more primary studies that addressed the same hypothesis in the same way.

74
Q

How are studies weighted in a meta-analysis?

A

according to size and uncertainty of odds ratio

75
Q

In a Forest plot, what is the size of the square proportional to?

A

Weight given to the study

76
Q

How is the null hypothesis shown on a Forest plot?

A

a line that runs vertically (solid or dashed)

77
Q

What should all studies in a meta-analysis be similar in?

A 
study design
participant profile
treatments/exposures
outcomes measured
statistical analysis used
78
Q

What does a Fixed Effects Model assume?

A

That the studies are estimating exactly the same effect size.

79
Q

What does a Random Effects Model assume?

A

That the studies are estimating similar, but not the same, effect sizes.

80
Q

Which of FEM and REM has the more evenly distributed weights?

A

Random effects model (REM)

81
Q

In which of FEM and REM is the confidence interval usually wider?

A

random effects model (REM)

82
Q

What is publication bias?

A

Larger studies or studies with statistically significant results or ‘favourable’ results are more likely to be published.

83
Q

What do we plot on a funnel plot?

A

results of studies against their size

84
Q

What do funnel plots test for and what are the results?

A

test for publication bias, if funnel shaped then there is no evidence of bias

85
Q

What is heterogeneity?

A

How different the studies within a meta-analysis are. Ideally we want very little heterogeneity within our meta-analysis.

HaDPop (Semester 2) (3 decks)

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