Public Health

Question 1

Cross Sectional

Case-Control

Cohort

Answer 1

Cross-section - looks at CURRENT freq disease and freq risk

Case-Control - retro; start w/ disease then look at who had exposure (odds ratio)

Cohort - retro or prospective; start w/ exposure then look at disease (relative risk)

Question 2

4 Phases of Clinical Trial

Answer 2

SWIM

I - safety (just healthy volunteers)

II - does it Work? (small # pts w/ disease)

III - Improvement (test against current drug or placebo)

IV - Monitor (post-marketing surveillance)

Question 3

Sensitivity

Specificity

Answer 3

Sensitivity - SCREEN

1 - rate false neg
TP/ (TP + FN)

Specificity - CONFIRM

1 - rate of false pos
TN / (TN + FP)

Question 4

PPV

NPV

Answer 4

PPV - if test is pos how likely to have disease

TP / (all pos) or TP / (TP + FP)
PPV increases w/ inc prevalence

NPV - if test is negative how likely to not have disease

TN / (all neg) or TN (TN + FN)
NPV decreases w/ inc prevalence

Question 5

Likelihood Ratio

Answer 5

Multiply LR by pre-test probability to estimate post-test odds

pos LR = true pos / false pos = sensitivity / (1-spec)

neg LR = false neg / true neg = (1-sens) / specificity

Question 6

What are ideal pos and neg likelihood ratios?

Answer 6

pos > 10

neg < .1

Question 7

Odds Ratio

Answer 7

odds if exp / odds if no exposure

a/b) / (c/d

Question 8

Relative Risk

Answer 8

Proportion of ppl w/ disease in exposure group / proportion of ppl w/ disease in non-exposure group

RR = 1 (no risk)

RR > 1 then inc risk if exposure

RR < 1 then dec risk if exposure

Question 9

Attributable Risk

Answer 9

Diff in risk b/n groups

Risk in exposed - Risk in unexposed

AKA how much risk can be explained by exposure

Question 10

Relative Risk Reduction

Answer 10

1 - RR

Proportion of risk reduction attributable to intervention compared to control

Question 11

Absolute Risk Reduction

Answer 11

Risk in intervention group - risk in control group

Question 12

Number Needed to Treat

Number Needed to Harm

Answer 12

NNT = 1/ARR

NNH = 1/ AR

Question 13

Standard Error Equation

Answer 13

SD / square root of sample size

So std error dec as inc sample size

Question 14

Type I Error

Type II Error

Answer 14

Type I - false pos (reject null when null is true)

alpha - prob of type I (usually set at .05)

Type II - false neg (do not reject null when there is an effect)

beta - prob of type II error

Question 15

Power (what inc it?)

Answer 15

1 - beta

Inc by …

• inc sample size
• in effect size
• inc precision of measurement

Question 16

When are confidence intervals significant?

Answer 16

If CI for mean diff between groups does not cross 0

If CI for odds ratio or relative risk does not include 1

If CIs between groups do not overlap

Question 17

Coefficient of Determination

Answer 17

r^2 in correlation

amount of variance in one variable that can be explained by variance in the other variable

Question 18

Order of Surrogate Decision Making

Answer 18

Spouse - adult children - parents - siblings

Question 19

Health Maintenance Organization

Answer 19

Restricted to limited panel of providers in network

Denied payment for services that do not meet established guidelines

Need referral to see specialist

Question 20

Point of Service

Answer 20

Can see out-of-network providers but higher copays and costs

Need referral to see specialist

Question 21

Preferred Provider Organization

Answer 21

Can see in or out of network but all have higher cost

do NOT need referral to see specialist

Question 22

Exclusive Provider Organization

Answer 22

Limited to a network

do NOT need referral to see specialist

Question 23

Medicare Parts A-D

Answer 23

A - hospital and hospice

B - basic medical bills (doctors office fees and diagnostic tests)

C - combo of A and B from private company

D - prescription drugs

hospitAl, Basics, Combo, Drugs