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PCM2 > Exam 11 > Flashcards

Exam 11 Flashcards

1
Q

Define informed consent.

A

Duty to disclose risks, benefits, and alternatives to treatment

Patient must have capacity, cannot be coerced

Reasonable physician standard, reasonable patient standard

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2
Q

An adult with capacity has the right to make health care decisions for him or herself. What about a minor? An adult that lacks capacity?

A

Minor - typically require a parent or legal guardian to make healthcare decisions

Adult that lacks capacity - surrogate decision maker

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3
Q

What are some limits to parental authority?

A

Generally cannot refuse a lifesaving medical treatment

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4
Q

5 exceptions to confidentiality

A
  1. Continued treatment
  2. Consent
  3. Communication of a threat
  4. Compliance with the law
  5. Court order
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5
Q

Measures the total number of people with a condition of interest at a given point in time

A

Prevalence

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6
Q

Measures the number of new cases that arise in a population without the condition of interest over a given period of time

A

Incidence

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7
Q

What does a standardized mortality ratio of 1.2 mean?

A

There are 20% more deaths in this population than would be expected relative to other populations

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8
Q

What are the 2 types of epidemiological studies?

A
  1. Descriptive

2. Analytic

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9
Q

What are the 2 types of descriptive epidemiological studies?

A
  1. Case report

2. Case series

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10
Q

What are the two categories of analytical epidemiological studies?

A
  1. Observational

2. Interventional

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11
Q

What are the 5 types of observational studies?

A
  1. Community surveys
  2. Ecological
  3. Cross-sectional
  4. Case-control
  5. Cohort
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12
Q

What are the 2 types of interventional studies?

A
  1. Clinical trial (randomized control, non-inferiority, equivalence)
  2. Community intervention
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13
Q

Studies done looking at variables at the group or population level

A

Ecological

Advantages - can use when measurement of individual level variables is not possible or ethical, quick, cheap, quick assessment of a health status in a community

Disadvatnages - bias, ecological fallacy

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14
Q

Type of clinical trial exploring if a new treatment is “no worse” than a current treatment

A

Non-inferiority

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15
Q

One sided trial vs. two sided trial

A

1 - non-inferiority

2 - equivalence

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16
Q

Type of clinical trial that shows a new treatment should not be inferior to NOR superior to current treatment (not different - good for generic medications)

A

Equivalence trials

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17
Q

Study that randomizes communities instead of individuals

A

Community interventions

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18
Q

Comprehensive review of many studies to summarize findings on a particular health topic

A

Systematic review

Advantages - more studies/sources provide more information, cheaper than repeating studies, results more generalizable than individual studies, strong evidence-based resource

Disadvantages - can be difficult to combine studies, summary only as good as the individual source

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19
Q

Statistical analysis of multiple studies to develop a single conclusion

A

Meta-analysis

Advantages - more studies = greater statistical power, more complex analysis, can do subgroup analysis

Disadvantages - advanced statistical techniques needed, heterogeneity of study population/study can make extraction difficult, possible publication bias, only as good as source

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20
Q

Quantitative measure of difference between groups

A

Effect size

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21
Q

Assumption - if all studies included were very large, they would all yield the same results; studies results can only vary by chance

A

Fixed-effect model

very restrictive, over-estimates precision, does not allow for study heterogeneity

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22
Q

Assumption - studies included are a random sample from all studies that addressed the question; study questions might be different but are related enough to be combined

A

Random-effect model

more conservative, will slow less statistical significance, more realistic, allows for study heterogeneity

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23
Q

Describe features of a forest plot - square, horizontal line, diamond

A

Each study is a square, size proportional to weight of study

Confidence interval is the horizontal line

Summary effect is diamond

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24
Q

Variability in study outcomes between studies

A

Heterogeneity

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25
Q

How can heterogeneity be assessed?

A 
Forest plots
Statistical tests (Cochran Q test, I^2 statistic)
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26
Q

Features of a Cochran Q test

A

Statistical significance - yes/no
Assumption - underlying effect in each study is the same
Low p value indicates significant heterogeneity
Recognized as a poor test

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27
Q

Measures the magnitude of variability between studies

A

I^2 statistic

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28
Q

How can you assess the cause of heterogeneity?

A
  1. Subgroup analyses - assess separate criterion in each study to see if at a subgroup level there is still significant heterogeneity (categorical variables)
  2. Meta-regression - assess separate criterion in each study to see if at a subgroup level there is still significant heterogeneity (continuous variables)
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29
Q

Studies with significant results published earlier than those with non-significant findings indicate ___ bias.

A

Time-lag

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30
Q

Define publication bias

A

Only positives studies published

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31
Q

How can bias be assessed?

A

Kappa statistic (interrater reliability, >0.75 excellent, <0.40 poor)
Bias risk scale
Funnel plots

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32
Q

Maternal mortality rate = ?

A

Number of deaths/100,000 live births

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33
Q

Neonatal mortality rate = ?

A

Number of deaths in first 28 days/1,000 live births

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34
Q

Infant mortality rate = ?

A

Number of deaths in children <1 y/o divided by 1,000 live births

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35
Q

Mortality rate = ?

A

Total deaths in a time interval or cause-specific deaths/1,000 or 100,000

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36
Q

Standardized mortality rate = ?

A

Observed deaths in a population/expected deaths in a standard population

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37
Q

Case fatality rate = ?

A

of deaths in a population of people who have a disease/total number of people who have a disease (in a given period of time)

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38
Q

Morbidity rate = ?

A

of non-fatal cases of a disease in a population

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39
Q

Attack rate = ?

A

of cases of disease ina population during a specific time period

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40
Q

Secondary attack rate = ?

A

new cases of a specified disease among contacts of known cases/size of contact population at risk

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41
Q

Prospective studies are what?

A

Cohort studies

42
Q

Retrospective studies are what?

A

Case-control studies

43
Q

Absolute risk = ?

A

New cases in a period of time/population at risk = incidence

44
Q

Relative risk = ?

A

Probability of getting disease in exposed/probability of getting disease in non-exposed = (A/(A+B))/(C/(C+D))

45
Q

Attributable risk = ?

A

(A/(A+B)) - (C/(C+D))

Proportion of risk attributable to exposure

46
Q

RR > 1?

A

Increased risk of outcome in exposed group

47
Q

RR = 1?

A

No difference in risk between exposed and unexposed

48
Q

RR < 1?

A

Reduced risk in exposed group

49
Q

Determines how risk decreases with treatment

A

Absolute risk reduction

50
Q

ARR = ?

A

(C/(C+D)) - (A/(A+B))

+ value - % prevented
- value - increases risk

51
Q

Number of people you need to treat in order to prevent disease in one person = NNT = ?

A

1/ARR

52
Q

Number of people needed to treat for one person to suffer a harmful event = NNH = ?

A

1/Attributable risk

53
Q

Population attributable risk = ?

A

Incidence (population) - Incidence (unexposed)

Proportion of the disease incidence in the population due to exposure, aka disease incidence that would be eliminated if exposure were eliminated

54
Q

Population attributable risk percent = ?

A

PAR/Incidence (population)

% of the disease incidence in the population that is due to the exposure = disease incidence that would be eliminated if exposure were eliminated

55
Q

When are odds ratios used?

A

Case-control (retrospective) studies

56
Q

Probability is used to calculate ___ vs. odds is used to calculate ___.

Both describe the likelihood of an event occurring

A

RR; odds ratios

57
Q

Ratio of outcome, value from 0 to infinity

A

Odds

58
Q

Fraction of an outcome when every outcome is considered, (0-1)

A

Probability

0 - impossible
1 - inevitable

59
Q

OR = ?

A

Odds of having disease in exposed/odds of having disease in unexposed = AD/BC

60
Q

Hazard ratio = ?

A

Hazard in the intervention group/hazard in the control group

Hazard = probability that an event will occur at any given moment in time

61
Q

HR = 0.5?

A

Half as many patients in treatment group are experiencing the event compared to controls

62
Q

HR = 1?

A

Event rates same between groups

63
Q

HR = 2?

A

2x as many patients in treatment group are experiencing event compared to controls

64
Q

Tells us how many times more (or less) likely a test result is found in a diseased vs. non-diseased group; depends on odds, not probability

A

Likelihood ratio

65
Q

Odds = ?

A

Probability of an event/(1- probability of event)

66
Q

Probability = ?

A

Odds/(1+ odds)

67
Q

LR + = ?

A

Diseased people with + test/non-diseased people with + test = sensitivity/(1-specificity)

68
Q

LR - = ?

A

Diseased people with test/non-diseased people with test = 1 - sensitivity/(Specificity)

69
Q

If LR + is > 1…

A

Increased likelihood of disease if test result is +

70
Q

If LR - is <1…

A

Decreased likelihood disease if test is negative

71
Q

Validity - aka ?

A

Accuracy

72
Q

Reliability - aka?

A

Precision (reproducibility)

73
Q

Causal criteria include…

A

Temporality (cause precedes effect)
Strength (strong association)
Dose-response (larger exposures lead to highe rrates of disease)
Reversibility (reduced exposure leads to lower rates of disease)
Consistency
Biologic plausibility (known MOA)
Specificity (singular cause for disease)
Analogy (other similar exposures cause same disease)

74
Q

Type of bias - if researchers know which treatment a study participant is getting, they may treat the participant differently

A

Ascertainment bias

Prevent with allocation and double blinding

75
Q

Type of bias - occurs when participants are selected in such a way that they differ in variables that affect the outcome other than the variable being studied or the sampled population does not reflect the general population

A

Selection/sampling bias

76
Q

Hawthorne effect?

A

Participants know they are being studied so they act differently

77
Q

Early detection of a disease leads to an apparent increase in overall survival (screening does not affect the natural history of disease)

A

Lead-time bias

78
Q

Occurs when a screening test is mroe likely to detect a slowly developing cancer but misses rapidly progressive cancer - cancers picked up by screening tend to be less aggressive, these patients do better

A

Length-time bias

79
Q

___ is an assumption about a population of interest; what are the 2 types?

A

Hypothesis

Null - hypothesis of no difference (no association)
Alternative - some difference (some association)

80
Q

Alpha value?

A

Level of significance

(Probability of a false positive RE significance = Type I error)

Standard is 0.05

81
Q

Alpha < 0.05 ?

A

Results occurred by chance 5% of the time

82
Q

P value?

A

Calculated probability from the study data; helps us determine significance

83
Q

Compare p and alpha value -

A

If p value is less than or equal to alpha value, reject the null, statistically significant

84
Q

Type II or beta error

A

Probability of a false negative

85
Q

Probability of rejecting the null hypothesis when it is false

A

Study power (probability of a true positive)

86
Q

Power = ?

A

1 - beta

87
Q

___ reduces both types of error; ___ reduces type II error.

A

Increase sample size; increase power

88
Q

Range f values that are likely to include the true effect size

A

Confidence interval

89
Q

Rule - Gaussian distribution

A

68 (1 SD)
95 (2 SD)
99 (3 SD)

90
Q

Negative skew

A

Shifts to the right

91
Q

Positive skew

A

Shifts to the left

92
Q

Compares means between 2 different groups

A

T-test

93
Q

Used to see if there is an association between categorical or nominal variables

A

Chi-square goodness of fit test

Compares proportions, determines if the observed proportions between data categories are significantly different than what would be expected by theory

Used when there is 1 categorical variable with 2+ values

(Sex - M/F), age, types of cars

94
Q

Chi squared = ?

A

Sum of [(observed - expected)^2]/expected

95
Q

Degrees of freedom = ?

A

k - 1

k = # of levels of categorical value
a

96
Q

Test to compare means of two distinct sample groups

A

Independent t-test

97
Q

Test to compare one sample mean with a known population mean (?)

A

Single sample t-test

98
Q

Test to compare two categorical variables/if there is a relationship between them

A

Chi-square test of independence

Categorical = hour of day, # produced

99
Q

Test with two independent variables and 1 dependent variable

A

ANOVA

100
Q

___ validity tells us if the results are believable and trustworthy for the sample of people in the study vs. ___ validity tells us if the results could be applied to total population

A

Internal; external

101
Q

CI indicating results are not statistically significant

A

If CI includes 0 or 1

102
Q

3 things that increase the power of a study

A

Increase sample size, increase effect size, Decrease type 2 error

PCM2 (16 decks)

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