Biostats Flashcards

Question

Power is the probability of avoiding a type II error and is equal to...

Answer 1

1- beta (typically 0.9 or 0.8)

Answer 2

(# of subjects in a group with an unfavorable event) /(total # of subjects in a group)

Answer 3

risk in treatment group/risk in the control group

Answer 4

no difference in risk

Answer 5

higher risk in the tx group

Answer 6

a lower risk in the tx group

Answer 7

patients treated with metoprolol were 57% as likely to have progression of disease as placebo-treated patients

Answer 8

how much the risk is reduced in the treatment group, compared to the control group

Answer 9

(% risk in control group- % risk in the treatment group)/ (% risk in the control group)

Answer 10

43% less likely to have HF progression than placebo-treated patients

Answer 11

absolute difference in outcome rates between 2 groups

Answer 12

(% risk in the control group) - (% risk in treatment group)

Answer 13

12 fewer patients will have HF progression

Answer 14

1 patient to benefit

Answer 15

1/ [(risk in control group) - (risk in treatment group)]

Answer 16

1/ARR (as a decimal)

Answer 17

9 (round up)

Answer 18

1 patient to experience harm (adverse event)

Answer 19

1/ARR (as a decimal; use absolute value if negative)

Answer 20

90 (round down)

Answer 21

odds of unfavorable events, or odds ratio (OR), is calculated instead. May also be used in cohort or cross-sectional studies.

Answer 22

that serotonergic ADs are associated with a 23% increased risk of falls with fracture

Answer 23

are associated with a 23% increased risk of falls with fracture (in this case, OR>1)

Answer 24

an unfavorable event (usually mortality) occurs within a short period of time

Answer 25

(hazard rate in the tx group)/(hazard rate in the control group)

Answer 26

the same in both groups

Answer 27

higher in the tx group

Answer 28

lower in the tx group

Answer 29

Ex. HF progression

Answer 30

Often used to increase the likelihood of reaching a statistically significant benefit with a smaller, less costly trial. However, all endpoints must be similar in magnitude and have similar, meaningful importance to the patient.

Answer 31

to be measured and reported when the composite endpoint is used

Answer 32

- if 1 group (one-sample t-test or paired t-test if 1 group has before and after measures) - if 2 groups (unpaired student t-test) - if 3 groups: ANOVA (F-test)

Answer 33

- if 1 group: Chi-square test - if 1 group has before and after measures: Wilcoxon Signed-Rank test - if 2 groups: Chi-square or Fisher's exact test. Mann-Whitney (Wilcoxon Rank-Sum) test may be preferred for ordinal data. - if 3 or more groups: Kruskal-Wallis test

Answer 34

- If 1 group: sign test or Wilcoxon Signed-Rank test (if one group has before and after measures) - If 2 groups, Mann-Whitney (Wilcoxon Rank-Sum) test - If 3 or more groups: Kruskal-Wallis test

Answer 35

it is used for smaller sample sizes

Answer 36

one variable changes, or is related to, another variable

Answer 37

causal relationship between variables

Answer 38

ordinal, ranked data

Answer 39

``` continuous data (r ranges from -1 to 1) 1= strong positive correlation; -1= strong negative correlation ```

Answer 40

one or more independent variables

Answer 41

1) linear, for continuous data 2) logistic, for categorical data 3) Cox regression, for categorical data in a survival analysis

Answer 42

a test will be positive in all patients with the condition

Answer 43

a test will be negative in all patients without the condition

Answer 44

data for all patients originally allocated to each tx group, even if the patient did not complete the trial according to the study protocol

Answer 45

data only from the subjects who completed the study according to the protocol (less applicable to real-world)

Answer 46

that a new treatment has roughly the same effect as a reference treatment

Answer 47

that a new treatment is no worse than the current standard based on the predefined non-inferiority (delta) margin

Answer 48

the minimal difference in effect between the 2 groups that is considered clinically acceptable base on previous research

Answer 49

different data or ratio data. The vertical line is the line of no effect (0 for difference data and 1 for ratio data).

Answer 50

the data falls to the left of the line (data to the right indicates significant harm)

Answer 51

direct, indirect, and intangible costs

Answer 52

medical events that occur as a result of the treatment or intervention

Answer 53

consequences of the disease or treatment as reported by the patient or caregiver (e.g. patient satisfaction, quality of life)

Answer 54

Ex. if a tx costs $50 to generate successful outcomes in two patients, the average cost-effectiveness ratio is $25/treatment success ($50/2 successfully treated patients)

Answer 55

represents the change in costs and outcomes when two tx alternatives are compared.

Answer 56

(C2-C1)/(E2-E1)

Answer 57

costs of interventions with therapeutic equivalence (easiest to calculate, but limited)

Answer 58

compares benefits and costs in monetary units (can be hard to assign a $ amount to a benefit)

Answer 59

the clinical effects of 2 or more interventions to the respective costs. Outcomes are similar to clinical trials (e.g length of stay, cure rate, change in BP). Inputs are measured in dollars (e.g. pharmacist time, drug costs)

Answer 60

quality-adjusted life-years (QALYs) and disability-adjusted life years (DALYs)

Answer 61

``` 1) Meta-analysis 2 RCTs 3) Cohort studies 4) Case-control series 5) Case series ```

Answer 62

There is a 95% chance that the CI range contains the true population value for reduction in serum Na with LoSod.

Answer 63

start with the exposure, looking for disease

Answer 64

start with the disease, looking for exposure

Answer 65

mean, median, and mode are all the same value

Answer 66

the trial may not have adequate statistical power (performing a larger trial will increase power, which increases the probability that a type II error will be avoided.

Answer 67

Patients exposed to amiodarone were 12 times more likely to develop pulmonary fibrosis than those not exposed.

Answer 68

identify and measure the costs and outcomes to ensure healthcare resources are used wisely

Answer 69

the null hypothesis was rejected correctly