Chapter 1 - Epidemiology and clinical analysis

Question 1

Define: type II error

Answer 1

Failure to reject null hypothesis when it is false

Beta = probability of making type II error

Question 2

Level of evidence: systemic reviews of case-control studies with homogeneity

Answer 2

3a

Question 3

Level of evidence: individual cohort studies

Answer 3

2b

Question 4

Level of evidence: All or non trials

Answer 4

1c

Question 5

Level of evidence: systematic reviews of cohort studies with homogeneity

Answer 5

2a

Question 6

Define: Kaplan-Meier method

Answer 6

Each event recorded at time of occurrence without the need for fixed time frames

Question 7

Definition: clinical equipoise

Answer 7

Situation in which clinical experts professionally disagree on the preferred treatment method

Question 8

Name: weighted composite dependent variable graph used in meta analyses

Answer 8

Forest plot

Question 9

Define: selection bias

Answer 9

Effect tested differs among patients who participate to those who do not

Can be due to physicians or patients (self-selection)

Question 10

Level of evidence: clinical outcome studies

Answer 10

2c

Question 11

Define: type I error

Answer 11

Rejection of null hypothesis when it is true

Alpha = probability of making type I error

Question 12

Define: censorship variable

Answer 12

Data about the event of interest are unknown because of withdrawal or failure to follow up

Question 13

Level of evidence: individual RCT with narrow confidence intervals

Answer 13

1b

Question 14

Define: Bayesian inference

Answer 14

Probabilities conditional on observations and with degrees of uncertainty; the use of odds ratio reflects this

Question 15

Level of evidence: case-series studies

Answer 15

4

Question 16

Define: power

Answer 16

Probability of rejecting the null hypothesis when it is false

Ability to detect true difference

1 - beta

Question 17

Define:

internal validity

statistical validity

construct validity

external validity

Answer 17

Internal validity: ability to support the causal effect being tested

Statistical validity: ability to generalize the effect to the larger population from the sample drawn

Construct validity: support the intended interpretation of the effect

External validity: support the generalization of results to external populations from which samples are not drawn

Question 18

Define: VascuQol

Answer 18

Vascular quality of life questionnaire

5 domains: pain, symptoms, activity, social, emotional

Question 19

Epidemiology is greek for

Answer 19

Upon - the people - study

Question 20

Define: confounding factor

Answer 20

Second variable correlates with a primary independent variable and its associated dependent variable

Question 21

Level of evidence: individual case-control studies

Answer 21

3b

Question 22

Define: propensity scoring

Answer 22

Control confounding factors to reflect conditional probability of being in a treatment group based on known variables. Carefully chosen to reflect potential predictors of treatment assignment (not outcomes of assignment)

Question 23

Define: information bias

Answer 23

Erroneous information collected by study because of poor design

Question 24

Define: validity

Answer 24

Degree to which an instrument measures what it is intended to measure

= accuracy

Question 25

Define: carryover effect

Answer 25

Influence of time and previous exposure of the other treatment

Question 26

Definition: prevalence and incidence

Answer 26

Prevalence = ratio of persons affected for the population at risk Incidence = ratio of persons in whom the disease develops within a specified period for the population at risk | (frequency of the disease at the measured time point regardless of the time of disease development)

Question 27

Table: Grade of recommendation, recommendation and basis

Answer 27

Question 28

List: Limitations of RTC's

Answer 28

1) costly to conduct 2) lack of clinical equipoise 3) bias from physician or patient even with clinical equipoise 4) risk aversion or randomization aversion 5) intent to treat analysis with high crossover or dropout 6) conducted at high volume centers and therefore not representative 7) designed and powered to test only one hypothesis

Question 29

Define: block randomization

Answer 29

Randomizing patients in a study in groups as they are enrolled

Question 30

Define: SF-36

Answer 30

Short form health survey for measurement of health-related quality of life instrument 8 domains physical: physical functioning, physical role, body pain, general health mental: vitality, social functioning, emotional role, mental health

Question 31

Define: recall bias

Answer 31

Cannot recall events accurately or have bias in recall

Question 32

Define: Koch's postulate (Robert Koch)

Answer 32

Postulate linking microbe and disease

Question 33

Level of evidence: systematic reviews of RCT study with homogeneity

Answer 33

1a

Question 34

Who is John Snow

Answer 34

Recognized for ameliorating cholera epidemic in 1854 London

Question 35

Define: reliability

Answer 35

Consistency of the instrument if it were to be repeated on the same participant under identical conditions = precision

Question 36

Level of evidence: expert opinion without critical appraisal or based on bench research

Answer 36

5

Question 37

Define: EQ-5D

Answer 37

European quality of life group instrument for quality of life assessment 5 dimentions of health: mobility, self-care, usual activities, pain/discomfort, anxiety/depression

Question 38

Define: counterfactual ideal

Answer 38

Impracticality of conducting study to expose people to certain things

Question 39

Define: WIQ

Answer 39

Walking impairment questionnaire 4 components: walking distance, walking speed, stair climbing, other symptoms that limib walking

Question 40

Define: survival analysis

Answer 40

Event status between fixed periods of measurement

Question 41

Statistical tests based on research question and data characteristics 1 group, 2 independent, 2 related, 3+ independent, 3+ related, 2 comparable variable, 1 dependent variable and 2+ independent variables

Answer 41

One group parametric: one sample t-test nonparametric: sign test, Wilcoxon signed rank, transform data for t-test proportions: exact binomial, z approximation to exact test Two independent parametric: t-test nonparametric: Wilcoxon rank-sum proportions: chi squared, Fisher's exact Two related parametric: paired t-test nonparametric: sign, Wilcoxon signed rank proportions: McNemar or kappa statistic Three or more independent parametric: ANOVA nonparametric: Kruskal-Wallis proportions: chi square, Fischer's exact Three or more related parametric: repeated-measures ANOVA nonparametric: ANOVA by ranks Two comparable variable nominal: relative risk ordinal: Spearman's rank correlation continuous: linear regression One dependent and two or more independent variables binary dependent: logistic regression categorical dependent: ANCOVA continuous dependent: multiple linear regression censored observation: COX proportional hazards model clustered or hierarchic parametric data: linear mixed models clustered or hierarchic semi-parametric data: generalized estimating equations

Question 42

Define: life-tables

Answer 42

Measure events at fixed intervals