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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
How can heterogeneity be assessed?
``` Forest plots Statistical tests (Cochran Q test, I^2 statistic) ```
26
Features of a Cochran Q test
Statistical significance - yes/no Assumption - underlying effect in each study is the same Low p value indicates significant heterogeneity Recognized as a poor test
27
Measures the magnitude of variability between studies
I^2 statistic
28
How can you assess the cause of heterogeneity?
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)
29
Studies with significant results published earlier than those with non-significant findings indicate ___ bias.
Time-lag
30
Define publication bias
Only positives studies published
31
How can bias be assessed?
Kappa statistic (interrater reliability, >0.75 excellent, <0.40 poor) Bias risk scale Funnel plots
32
Maternal mortality rate = ?
Number of deaths/100,000 live births
33
Neonatal mortality rate = ?
Number of deaths in first 28 days/1,000 live births
34
Infant mortality rate = ?
Number of deaths in children <1 y/o divided by 1,000 live births
35
Mortality rate = ?
Total deaths in a time interval or cause-specific deaths/1,000 or 100,000
36
Standardized mortality rate = ?
Observed deaths in a population/expected deaths in a standard population
37
Case fatality rate = ?
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)
38
Morbidity rate = ?
of non-fatal cases of a disease in a population
39
Attack rate = ?
of cases of disease ina population during a specific time period
40
Secondary attack rate = ?
new cases of a specified disease among contacts of known cases/size of contact population at risk
41
Prospective studies are what?
Cohort studies
42
Retrospective studies are what?
Case-control studies
43
Absolute risk = ?
New cases in a period of time/population at risk = incidence
44
Relative risk = ?
Probability of getting disease in exposed/probability of getting disease in non-exposed = (A/(A+B))/(C/(C+D))
45
Attributable risk = ?
(A/(A+B)) - (C/(C+D)) Proportion of risk attributable to exposure
46
RR > 1?
Increased risk of outcome in exposed group
47
RR = 1?
No difference in risk between exposed and unexposed
48
RR < 1?
Reduced risk in exposed group
49
Determines how risk decreases with treatment
Absolute risk reduction
50
ARR = ?
(C/(C+D)) - (A/(A+B)) + value - % prevented - value - increases risk
51
Number of people you need to treat in order to prevent disease in one person = NNT = ?
1/ARR
52
Number of people needed to treat for one person to suffer a harmful event = NNH = ?
1/Attributable risk
53
Population attributable risk = ?
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
Population attributable risk percent = ?
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
When are odds ratios used?
Case-control (retrospective) studies
56
Probability is used to calculate ___ vs. odds is used to calculate ___. Both describe the likelihood of an event occurring
RR; odds ratios
57
Ratio of outcome, value from 0 to infinity
Odds
58
Fraction of an outcome when every outcome is considered, (0-1)
Probability 0 - impossible 1 - inevitable
59
OR = ?
Odds of having disease in exposed/odds of having disease in unexposed = AD/BC
60
Hazard ratio = ?
Hazard in the intervention group/hazard in the control group Hazard = probability that an event will occur at any given moment in time
61
HR = 0.5?
Half as many patients in treatment group are experiencing the event compared to controls
62
HR = 1?
Event rates same between groups
63
HR = 2?
2x as many patients in treatment group are experiencing event compared to controls
64
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
Likelihood ratio
65
Odds = ?
Probability of an event/(1- probability of event)
66
Probability = ?
Odds/(1+ odds)
67
LR + = ?
Diseased people with + test/non-diseased people with + test = sensitivity/(1-specificity)
68
LR - = ?
Diseased people with test/non-diseased people with test = 1 - sensitivity/(Specificity)
69
If LR + is > 1...
Increased likelihood of disease if test result is +
70
If LR - is <1...
Decreased likelihood disease if test is negative
71
Validity - aka ?
Accuracy
72
Reliability - aka?
Precision (reproducibility)
73
Causal criteria include...
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
Type of bias - if researchers know which treatment a study participant is getting, they may treat the participant differently
Ascertainment bias Prevent with allocation and double blinding
75
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
Selection/sampling bias
76
Hawthorne effect?
Participants know they are being studied so they act differently
77
Early detection of a disease leads to an apparent increase in overall survival (screening does not affect the natural history of disease)
Lead-time bias
78
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
Length-time bias
79
___ is an assumption about a population of interest; what are the 2 types?
Hypothesis Null - hypothesis of no difference (no association) Alternative - some difference (some association)
80
Alpha value?
Level of significance (Probability of a false positive RE significance = Type I error) Standard is 0.05
81
Alpha < 0.05 ?
Results occurred by chance 5% of the time
82
P value?
Calculated probability from the study data; helps us determine significance
83
Compare p and alpha value -
If p value is less than or equal to alpha value, reject the null, statistically significant
84
Type II or beta error
Probability of a false negative
85
Probability of rejecting the null hypothesis when it is false
Study power (probability of a true positive)
86
Power = ?
1 - beta
87
___ reduces both types of error; ___ reduces type II error.
Increase sample size; increase power
88
Range f values that are likely to include the true effect size
Confidence interval
89
Rule - Gaussian distribution
68 (1 SD) 95 (2 SD) 99 (3 SD)
90
Negative skew
Shifts to the right
91
Positive skew
Shifts to the left
92
Compares means between 2 different groups
T-test
93
Used to see if there is an association between categorical or nominal variables
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
Chi squared = ?
Sum of [(observed - expected)^2]/expected
95
Degrees of freedom = ?
k - 1 k = # of levels of categorical value a
96
Test to compare means of two distinct sample groups
Independent t-test
97
Test to compare one sample mean with a known population mean (?)
Single sample t-test
98
Test to compare two categorical variables/if there is a relationship between them
Chi-square test of independence Categorical = hour of day, # produced
99
Test with two independent variables and 1 dependent variable
ANOVA
100
___ 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
Internal; external
101
CI indicating results are not statistically significant
If CI includes 0 or 1
102
3 things that increase the power of a study
Increase sample size, increase effect size, Decrease type 2 error

PCM2 (16 decks)

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