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TOP 300 drugs - NAPLEX > Biostatistics > Flashcards

Biostatistics Flashcards

1
Q

Continuous data

A

values that change by the same amount
2 types: ratio and interval data

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2
Q

Ratio vs interval data

A

Interval data has no meaningful zero (e.g. celsius)
Ratio data has a meaningful zero (zero equals none, e.g. BP)

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3
Q

Discrete (categorical) data

A

Nominal, ordinal
Have categories

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4
Q

Differences between ordinal and continuous data

A

In ordinal data, the categories do not increase by the same amount

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5
Q

Measures of central tendency

A

Provide simple summaries of the data
Mean, Median, Mode

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6
Q

Spread (variability) of data

A

Range
Standard deviation (how dispersed the data is from the mean)

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7
Q

Gaussian distributions

A

Normal (Bell-shaped)
Large sample sets of continuous data

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8
Q

Characteristics of a gaussian distribution

A

Symmetrical curve
Median, Median and Mode are all the same
68% of the values fall within 1 SD, 95% of the values fall within 2 SDs

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9
Q

What causes skewed (not symmetrical) distributions?

A

small sample size +/- outliers

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10
Q

When is the Median a better measure of central tendency?

A

When there are outliers on a small # of values. In this case, the outliers can have a big impact on the mean.

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11
Q

alpha

A

error margin
commonly 5% (0.05)

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12
Q

Determining CI in ratio data vs difference data

A

Difference data (mean): not significant if the CI crosses 0 (e.g. change in FEV1)

Ratio data (OR, HR, RR): not significant if the CI crosses 1

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13
Q

CI & precision

A

Narrow CI = high precision
Wide CI = less precision

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14
Q

Type 1 error

A

False positives

When the alpha is set as 0.05 and the study reports a P value < 0.05, it is statistically significant and the probability of making a Type I error is 5%

**CI = 1 - alpha (type 1 error)

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15
Q

Type II error

A

Denoted as beta (B)

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16
Q

power

A

Power to avoid a type II error

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17
Q

How is power determined?

A

of outcomes
Difference in outcome rates
Significance (Alpha) level

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18
Q

Relative risk

A

risk in treatment group/risk in control group

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19
Q

Interpret a RR of 57%

A

Patients in the treatment group were 57% as likely to have the outcome as the placebo group

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20
Q

Relative risk reduction

A

1-RR

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21
Q

Interpret a RRR of 0.43

A

Patients in the treatment group were 43% less likely to have the outcome than the placebo group

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22
Q

Absolute risk reduction

A

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

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23
Q

Interpret a ARR of 12%

A

It means that 12 out of a 100 patients will benefit from the treatment

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24
Q

Number needed to treat

A

1/ARR
Always round up

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25
Q

NNH

A

Always round down

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26
Q

In what type of studies is odds ratio used?

A

Used in case-control studies to estimate the risk of unfavorable events

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27
Q

OR calcuation

A

AD/BC

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28
Q

Hazard ratio

A

Used in survival analysis
Rate at which an unfavorable event occurs over a short period of time

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29
Q

HR formula

A

HR (treatment group)/HR(control group)

30
Q

Interpret a HR of 2

A

Means that there are twice as many deaths in the treatment group

31
Q

Interpret a HR of 0.5

A

Means that there are half as many deaths in the treatment group

32
Q

When are parametric tests appropriate?

A

When data is normally distributed

33
Q

When are nonparametric tests appropriate?

A

When data is NOT normally distributed

34
Q

Parametric test for 1 group (continuous data)

A

One-sample T-test

35
Q

parametric test for 1 group (with before & after measurements) (continuous data)

A

Dependent/paired t-test

36
Q

parametric test for 2 groups (continuous data)

A

Independent/unpaired student t-test

37
Q

parametric test for ≥ 3 groups (continuous data)

A

ANOVA (or F-test)

38
Q

Discrete/Categorical test for 1 group

A

Chi-square test

39
Q

Discrete/Categorical test for 2 groups

A

Chi-square test or fisher’s exact test

40
Q

Correlation vs regression

A

Correlation - one variable
Regression - used to assess multiple independent variables or if there is a need to control many confounding factors

41
Q

Sensitivity

A

The true positive
100% sensitive test will be positive in ALL patients with the disease

42
Q

Specificity

A

The true negative
100% specific test will be negative in all patients without the disease

43
Q

Sensitivity formula

A

A (positive, have condition)/ A + C (negative, have condition)

44
Q

Specific formula

A

D (Negative, no condition)/B(positive, no condition) + D

45
Q

Interpret: sensitivity of 28%

A

Means that only 28% of the patients with the condition will have a positive result, but, 72% of patients with the disease can test negative (missed diagnosis)

46
Q

Interpret: specificity of 87%

A

Test is negative in 87% of patients without the disease, but 13% without the disease can test positive (incorrect diagnosis)

47
Q

Intention-to-treat vs per-protocol study

A

ITT: includes data for all patients originally allocated to each treatment group even if the patient did not complete the trial according to the study protocol

PP: analysis completed for only those that completed the study according to the protocol

48
Q

Equivalence vs non-inferiority trials

A

Equivalence: same effect as reference
Non-inferiority: no worse than reference

49
Q

Boxes in a meta-analysis

A

Show the effect estimate Size of the box correlate with the size of the effects from the single study shown

50
Q

Diamonds in a meta-analysis

A

Represent pooled results from multiple studies. Wider the diamond, the less reliable the study results.

51
Q

Horizontal lines in a meta-analysis

A

Illustrate the length of the confidence interval. The longer the line, the wider the interval and less reliable the study results

52
Q

vertical solid line in a meta-analysis

A

Line of no effect
“0” for difference data
“1” for ratio data

53
Q

Case-Control study: description

A

Compares patients w/ a disease (cases) to those without the disease (control). The outcome of the cases and controls are already known, but the researcher looks back in time to see if a relationship exists b/w outcome and risk factors

54
Q

Case-Control study: benefits

A

Data easy to collect
Good for looking at outcomes when intervention is unethical
Cheap

55
Q

Case-Control study: limitations

A

Cause & effect cannot be reliably be determined

56
Q

Cohort study: description

A

Compares outcomes of a group of patients exposed and not exposed to a treatment. Researcher follows both prospectively or retrospectively to see if they develop the outcome.

57
Q

Cohort study: benefits

A

Looking at outcomes when the intervention is unethical

58
Q

Cohort study: limitations

A

influenced by confounders
more time-consuming and expensive than a retrospective study

59
Q

Cross-Sectional survey

A

Estimates the relationship b/w variables & outcomes (prevalence) at one particular time (cross-section) in a defined population

60
Q

Case report and case series

A

Case report - unique condition/ADR that appears in a single patient
Case series - same but in a few patients

61
Q

Case reports/series: benefits

A

Can identify new diseases, drug side effects, or potential uses
Generates hypothesis that can be treated with other study designs

62
Q

Case reports/series: limitations

A

Conclusions cannot be drawn from a few cases

63
Q

Pharmacoeconomic research

A

Identifies, measures and compares the costs (direct, indirect & intangible) and the consequences (clinical, economic and humanistic) of pharmaceutical products and services

64
Q

Cost-effectiveness analysis

A

Used to compare the clinical effects of 2+ interventions to the respective costs

65
Q

Cost-minimization analysis (CMA)

A

Used when 2+ interventions have demonstrated equivalence in outcomes and costs of each are compared

66
Q

Cost-utility analysis

A

Includes a quality-of-life component of morbidity assessments, using common health indices such as QALYs and DALYs

67
Q

Cost-benefit analysis (CBA)

A

Comparing benefits & costs of an intervention in terms of monetary units (dollars)

68
Q

ECHO model

A

Economic, clinical and humanistic outcomes

69
Q

what is the purpose of pharmacoeconomic studies?

A

Guide optimal healthcare resource allocation

70
Q

Incremental cost-effectiveness ratios

A

Represent the change in costs & outcomes when 2 treatment alternatives are compared

71
Q

ICR formula

A

(C2-C1)/(E2-E1)

TOP 300 drugs - NAPLEX (12 decks)

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