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Y1&2 Medicine Zoe Veary > MHS > Flashcards

MHS Flashcards

1
Q

What are the three types of Systematic Error or Bias in clinical trials? And what is it minimised by?

A

Selection bias (selection, loss to follow up)
Information bias e.g. recall bias
Reporting bias e.g. publication bias
Minimised by study design, blinding and randomisation

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2
Q

What is a confounding error and what is it minimised by?

A

Known or unknown third factors associated with relationship under investigation
Minimsed by randomisation

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3
Q

What two types of random error are there?

A

Type 1 (alpha) or Type 2 (beta)

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4
Q

What is a type 1/alpha error? What is it controlled by?

A

False +ves

Level of significance

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5
Q

What is a type 2/beta error? What is it controlled by?

A

False -ves

Large sample sizes

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6
Q

What are the 3 main models of stress?

A

Stimulus, Response and Transactional

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7
Q

What are the 3 phases of stress?

A

Phase 1 - Alarm
Phase 2 - Resistance
Phase 3 - Exhaustion

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8
Q

What are the 2 sympathetic pathways (stress lectures)

A

SAM - sympathoadrenomedullary axis

HPA - hypothalamic pituitary adrenal axis

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9
Q

Where is serotonin made?

A

Raphe nucleus

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10
Q

Where is noradrenaline made?

A

locus coerulus

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11
Q

What are the 5 main categories of stressors?

A

Life events, internal stressors, physical, lifestyle and environmental

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12
Q

What is the choice principle?

A

That we should seek out events that are pleasurable and avoid those that are harmful or threatening

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13
Q

What is the yerkeses- dodson principle

A

Performance increases with mental and physiological arousal but only up to a point
Too high performance decreases and there is tension and anxiety

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14
Q

What is eustress?

A

Positive cognitive responses to stress e.g. athletic competition

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15
Q

What was the study by Seligman and Maier (1967) looking at?

A

Learned helplessness

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16
Q

What was the crowded train study?

A

Lundgberg 1976 - those who had been on the train from beginning were less stressed - were in control e.g. of finding and choosing where to seat

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17
Q

What study in 1976 also showed that giving people a sense of personal control increased health?

A

Langer and Rodin

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18
Q

What are the three types of decisions that have to be made?

A

Approach-approach
Avoidance - Avoidance
Approach - avoidance

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19
Q

What is the purpose of randomisation in RCT’s

A

to ensure potential confounders (known and unknown) are balanced between intervention and control group

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20
Q

What are the top 3 observational studies (in order)

A

Cohort studies
Case control studies
Self controlled case series

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21
Q

What is an experimental study?

A

Studies in which exposure is determined as part of the study design

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22
Q

What is an observational study?

A

Studies in which exposure is not determined as part of the study design. So already existing exposures and their consequences are studied

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23
Q

What is a null hypothesis?

A

The hypothesis being tested imagining there are no links between either factor being investigated

24
Q

What is an alternative hypothesis?

A

What is believed to be true if the null hypothesis is false

25
Q

What is the p value?

A

The probability of seeing a difference of size by chance

Smaller p value is more likely to be real result

26
Q

What does it mean if p=0.05

A

That 5% or 1/20 chance of seeing a difference of the size observed as a result of chance

27
Q

What p value is said to be a statistically significant difference?

A

p<0.05

0.5 or above the null hypothesis is rejected and alternative accepted

28
Q

What is a case control study?

A

A study where subjects are chosen on the basis of whether or not they have the disease or health related state - retrospective
Identification of exposure in the past

29
Q

What is a cohort study?

A

A study where the subjects are chosen on the basis of whether they are exposed or not - prospective
Recruitment of cases as they happen

30
Q

What does the WHO define health as?

A

A state of complete physical, mental and social well-being and not merely the absence of disease of infirmity

31
Q

What is health inequality?

A

difference in health status of individuals and groups

32
Q

What is health inequity?

A

unfair differences in health status that are potentially avoidable

33
Q

What does the marmot review describe?

A

proportionate universalism - how disadvantage starts before birth and accumulates throughout life

34
Q

What are epidemic models?

A

Sets of equations that describe the rate of change of numbers infected

35
Q

How do we “deal” with chance associations?

A

By statistics and defining a probability level that we find acceptable - the alpha level

36
Q

What is the accepted alpha level?

A

1/20 i.e p<0.05

37
Q

How do you deal with confounding variables in a study?

A

Study design: to restrict the study to one stratum of the confounder or match for potential confounders
Analysis: stratified analysis after having collected data on confounders

38
Q

What are residual confounding factors?

A

When all known confounders have been accounted for but there are other unknown confounders that are exaggerating or marking a true relationship

39
Q

What is the best way to deal with both known and unknown confounders?

A

randomisation

40
Q

What is incidence?

A

New events within a time dimension

41
Q

What is prevalence?

A

existing cases within a time

42
Q

What is point prevalence?

A

existing cases a specific time

43
Q

What is period prevalence?

A

existing cases over a time course

44
Q

What is cumulative incidence?

A

new cases over a time period but each with a different length of follow up

45
Q

What is standardisation?

A

Set of techniques used to remove as much as possible the effects of differences in confounders when comparing two or more populations

46
Q

What is indirect standardisation?

A

When from the reference population to find stratum specific rates and you apply these to the study population the generate the expect value –> then compare expected number of deaths with observed

47
Q

What is direct standardisation?

A

When from the study population to derive stratum specific rates and apply these to the reference population and derive the expected rate

48
Q

What is sensitivity?

A

The probability that a test on a patient with the condition will give a positive result = True positive
= true positive/total with condition

49
Q

What is specificity?

A

The probability that a test on a patient without the condition will give a negative result = true negative
= true negative/ total without the condition

50
Q

What is the positive predictive value?

A

The proportion of patients with positive test results that actually have the disease
= true positive/ total positive

51
Q

What is the negative predictive value?

A

The proportion of patients with negative test results that don’t have the disease
true negative/total negative

52
Q

How do you calculate attributable risk?

A

Difference between absolute risk for control and treatment groups

53
Q

How do you calculate absolute risk?

A

no of events/ total no of people

54
Q

How do you calculate relative risk?

A

Absolute risk of treatment group / absolute risk of control group

55
Q

What is a de facto census?

A

People are enummerated according to where they stay on census night

56
Q

What is a de juro census?

A

People are ennumerated according to where they usually live

Y1&2 Medicine Zoe Veary (60 decks)

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