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Exam 1 Flashcards

1
Q

What is interval data

A

has equal intervals between values but no true point zero
zero does not mean the absence of the quantity being measured

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2
Q

What is ratio data

A

meaningful zero that indicated none of the variable
zero represents a complete absence of the quantity

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3
Q

What is nominal data

A

no rank order
yes/no
dichotomous variables

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4
Q

What is ordinal data

A

categorical variables
difference between variables that cant be measured
often scales

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5
Q

What is continuous data and what are the two types of continuous data

A

process a logical sequence with values increasing or decreasing by uniform amounts
-Interval Data
-Ratio Data

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6
Q

What are the 3 common types of central tendency

A

mean (continuous, normal distr., SD, range)
median (ordinal, continuous, normal distr., IQR, range)
mode (nominal)

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7
Q

What is a positive skew and what is a negative skew

A

positive: right skew, more low values in dataset with high value outliers
negative: left skew, more high values with low value outliers

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8
Q

What is incidence

A

the rate of new cases of a disease or condition in a population over a specific period
incidence = (new cases/population at risk)*1000

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9
Q

What is prevalence

A

the total number of cases (new and existing) of a disease population
prevalence = (total cases/total population)*1000

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10
Q

What is the formula for RR (relative risk)

A

[A/(A+B)] / [C/(C+D)] = RR
ratio of incidence of an event occurring experiencing intervention to those not

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11
Q

What does RR mean when its higher than one, equal to one, and lower than one

A

higher than one: increased risk in treatment group
equal to one: no effect
lower than one: lower risk in treatment group

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12
Q

Relative Risk reduction

A

( [A/(A+B)] - [C/(C+D)] ) / [C/(C+D)]
amount of risk reduction relative to baseline risk
dont round

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13
Q

ARR (absolute risk reduction) calculation

A

[A/(A+B)] - [C/(C+D)]
indicates the net benefit of treatment over placebo

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14
Q

What is NNT formula

A

NNT = 1 / ARR
round UP

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15
Q

What is NNH

A

number of patients who need to be treated for one patient to experience harm
NNH = 1 / ARR
round DOWN

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16
Q

What is odds ratio (OR)

A

describes the probability of an event occurring in case-control studies
uses 2x2 table
OR = AD / BC

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17
Q

What does it mean when OR is higher than one, equal to one, and lower than one

A

OR higher than one: event rate in treatment group is higher
OR equal to one: event rate is same between groups
OR lower than one: event rate in treatment group lower

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18
Q

What is a type 1 error

A

False positive
Occur when null hypothesis is incorrectly rejected
Denoted by alpha**
(When alpha = 0.05 then 5% chance of making a type 1 error)

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19
Q

What is a type 2 error

A

False negative
Occurs when null hypothesis is incorrectly accepted
Means that no difference when there is one
Donated by beta
(Risk of type 2 error increases with a smaller sample size)

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20
Q

When should alpha and beta be determined

A

priori: prior to study
post host: after completion (bad)

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21
Q

If p < alpha the null is what

A

Rejected (significant result)

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22
Q

If p > alpha the null is what

A

Null is not rejected (not significant)

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23
Q

Confidence intervals (CI)

A

Range of numbers likely to contain the population interval
A method to determine stat significance: studies may report CI, p-value, or both
(Usually reported as 95% confidence interval)

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24
Q

If evaluating differences between groups the CI cannot cross what? If evaluating proportions, RR or OR, the CI cannot cross what?

A

0
1

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25
Stat significance is or is not equal to clinical significance
Is NOT
26
Fishers exact test
Two independent samples nominal data
27
Chi squared test
Two independent samples or 3 or more independent samples Nominal data
28
Stat tests that are named are ordinal/continuous that are nonparametric or continuous: parametric
ordinal/continuous that are nonparametric (mann-whitney U, wilcoxon signed ranks, krushal-wallis)
29
Univariate analyses
Comparison of one dependent variable to one independent variable -doesn’t account for confounders -may have stat significant results that are not accurate
30
Multi variable analysis
Compare one dependent variable to multiple independent variables -multiple variable = confounders or covariants -able to determine stat significance
31
Multi variable linear regression
Dependent variable is a continuous variable Independent variables can be nominal, ordinal, or continuous P values will be provided for each covariant and the relationship to the dependent variable
32
What is multicollinearity
Correlations exist between the variables indicating redundancy and potential bias (relationship exists between variables)
33
Multi variable logistic regression
Dependent variable is dichotomous variable Independent variable can be nominal, ordinal, or continuous Relationship is non linear
34
Survival analysis
Methods to determine time to an event If event is not experienced subject is surviving If event is experienced subject is failing Dependent variable is time
35
Censoring meaning
Done for incomplete data -If subjects are lost to follow up or do not have event they are censored -data for that patient included up until end of study or lost to follow up
36
Kaplan Meier method
Survival analysis -can’t account for relationship of covariates on survival -analysis cannot determine if the independent variable predicts survival MOST common log-ranked
37
What are the two ways to present the Kaplan Meier method
Survival function: cumulative frequency of subjects not experiencing event Hazard function: cumulative frequency of subjects experiencing the event
38
Cox proportional hazards model
Stat comparison accounting for covariates HR is reported
39
kaplan-meier, log rank, cox proportional hazard
kaplan-meier: estimation of survival curve log rank: stat comparison cox proportional hazard: stat comparison accounting for covariates
40
What is a non-inferior study
study design that aims to show that if a difference exists btw two treatments, it is small enough to conclude that the treatment has an effect similar to active control
41
What is active control vs test drug
active control: reference group, standard treatment, standard of care (comparator group) test drug: treatment in question or new therapy
42
Non-inferior study is only appropriate if test drug and standard of care have demonstrated superiority to what
placebo
43
What does hypothesis testing look like in non-inferior study
one-tailed null: test drug is not non-inferior to reference drug (two treatment groups are different) alternative: test drug is non-inferior to reference drug
44
When is the null rejected in non-inferior study
if CI does not exceed the non-inferiority margin OR p-value is less than alpha (P<0.05 = non inferior)
45
Stat analysis non-inferiority margin
pre-specified value used to show the test drug's treatment effect is not worse than reference drug -margin is the amount that test drug effect is worse than standard of care MUST be priori
46
How do investigators set p-value for non-inferior margin
if non-inferiority margin or CI not provided, the p-value and alpha can be used to determine stat significance
47
If non-inferiority is met, investigators can test if the test drug is _________ to standard of care
superior
48
What does these results mean: inferior, inconclusive, non-inferior
inferior: both bounds of the CI are above or below the non-inferiority margin inconclusive: one bound of CI is above or below non-inferiority margin, the test drug is possibly inferior non-inferior: both bounds of the CI are above or below the non-inferiority margin
49
Pre-protocol analysis is preferred in non-inferiority study, what can this cause
it requires subjects to follow the study protocol and will make it more difficult to accept the alternative hypothesis
50
What is the purpose of clinical practice guidelines
they provide recommendations for providing optimal patient care -utilizes EBM to make clinical decisions based on the BEST AVAILABLE EVIDENCE or clinical experience
51
What is the impact of clinical practice guidelines
potential to influence millions of decisions on medical interventions -important for med professionals to be familiar with guideline methodology and have the ability to evaluate the validity of the guidelines help guide treatment decisions
52
What are some issues with clinical practice guidelines
lag in the ability of information and research and incorporation into practice some are not updated regularly which may result in practitioners utilizing out of date interventions or meds due to lack of familiarity with primary literature
53
Guideline Development Methodology: Organizations
numerous organizations produce clinical practice guidelines -multiple orgs could produce guidelines on the same disease state select members of the orgs will sit on a guideline development committee -individuals chosen based on expertise in the field
54
Recommended steps for guideline development
developed by institute of medicine establish transparency -development and funding explicitly detailed management of conflict of interest they are unavoidable but should be kept to a minimum there should be no funding source for the guidelines
55
guidelines development group composition
should be multidisciplinary pt/consumer rep should be the guideline development group
56
What should each recommendation have for establishing evidence foundations
-a clear description of potential benefits and harms -summary of relevant available evidence (and gaps), description of the quality and quantity of evidence -impact of clinical expertise in forming the recommendation
57
Each recommendation for a star rating in establishing evidence foundations should have what
the level of confidence in the evidence supporting the recommendation strength of the recommendation (description and explanation if there were any differences in opinion on the guideline development group regarding the recommendation)
58
What is articulation of recommendations
recommendations should be in a standard format throughout the guideline
59
Recommended steps for guideline development: external review
should be externally reviewed (similar to peer review) by a wide audience
60
Recommended steps for guideline development: updating the guideline
date of systematic evidence review should be included in the guideline, along with a proposed date of the next guideline review guidelines should be updated when new significant evidence is released
61
Developing a systematic review is important for preparing the synthesis of _________ to develop guideline recommendations
evidence
62
Why is selecting an appropriate topic for creation of a guideline important
A topic or disease state guideline should be one that has the maximum potential for benefit to patients from guideline development
63
Define the clinical questions to be addressed meaning
The guideline development group should formulate clinical questions to be addressed in the guideline PICO is frequently utilized to develop the questions
64
Determine the study screening selection criteria meaning
The types of research to be included should be defined -Will the guideline include only RCTs, observational studies, a combination of these? -Will the guideline include unpublished evidence?
65
Other steps in Clinical Practice Guideline and Systematic Review Intersection
Conduct a systematic search for evidence Critically appraise individual studies Synthesize the body of evidence
66
Establishing Evidence Foundations for and Rating Strength of Recommendations
Recommendations will be evaluated and rated Several different rating systems are available One of the common standards is the GRADE system (uses PICO, have 3 components)
67
What are the three components of the GRADE system
Confidence rating in the recommendation Recommendation on benefits and harms Final recommendation for an intervention
68
GRADE: Confidence rating in the recommendation
-RCTs can be rated as high, moderate, low or very low -Observational studies can only be rated as low confidence -Confidence is lowered due to study: risk of bias, inconsistency, indirectness, imprecision, publication bias
69
GRADE: Recommendation on benefits and harms
Net benefits: Intervention does more good than harm Trade-offs: There are important trade-offs between the benefits and harms Uncertain trade-offs: It is not clear if the intervention does more good than harm No net benefits: The intervention clearly does not do more good than harm
70
GRADE: Final recommendation for an intervention
Weak recommendation for using an intervention Weak recommendation against an intervention Strong recommendation against using an intervention Strong recommendation for using an intervention
71
Guideline Evaluation
Guidelines should be assessed for the quality of published evidence prior to using in clinical practice Common tool used for clinical practice guidelines is the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument
72
Guideline Sources
no uniform database of where to find guidelines (not comprehensive)
73
How do practitioners find guidelines?
Know the societies that publish them

EBM-2 (2 decks)

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